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Dye-contaminated water from industry is hazardous to human and aquatic lives. Membrane technology is considered a viable approach to resolve the issue. Herein, copper oxide nanoparticles (CuO NPs) embedded in porous chitosan membranes have been prepared using a solution-casting approach with sodium tripolyphosphate as a crosslinker and polyethylene glycol as a porogen. The prepared membranes have been characterized by physicochemical, mechanical and photocatalytic properties. FTIR results indicate some hydrogen bonding across CuO NPs and the chitosan matrix. XRD and TGA analyses reveal that the membranes are thermally stable and somehow crystalline. SEM examination indicates that the membrane surfaces express porous/roughened texture. The contact angle measurement indicates that the pure chitosan and CuO NPs-embedded membranes are hydrophobic, whereas PEG-leached porous chitosan membranes express hydrophilicity. CuO NPs reinforcement has significantly improved the tensile strength, whereas the elongation at break decreased. The CuO NPs incorporated in chitosan membranes exhibit exceptional photocatalytic activities against methyl orange and methylene blue dyes for their effective removal from aqueous media. [ABSTRACT FROM AUTHOR]

ZnO/carbon composites were prepared via hydrothermal method and carbonization using zinc nitrate hexahydrate (Zn(NO3)2·6H2O) and glucose (C6H12O6) as zinc and carbon source, and ammonia as precipitation agent. The effects of glucose addition amount on the morphology and structure of ZnO/carbon composites were discussed. The chemical composition, morphology and structures of ZnO/carbon composites were characterized by XRD, FESEM, TG and Raman spectroscopy. The flower-like ZnO/carbon nanoparticle composites were obtained after carbonization at 600 °C for 2 h. The carbon content in ZnO/carbon composites increased with the increase of glucose, and the carbon content reached 28.8% when the glucose was 1.0 g. As the carbon content increases, carbon nanoparticles change from irregular particles to spherical particles, while the degree of graphitization of carbon in ZnO/carbon composites has not significant change. The photocatalytic performances of ZnO/carbon composites were studied by degradation of organic dye [rhodamine B (RhB) and methylene blue (MB)] under UV light irradiation, and the maximum degradation rate of RhB and MB reached 93.3% and 97.2%, respectively. [ABSTRACT FROM AUTHOR]

In this work, seven organic dyes were designed (M2–M7) to have the D-π1-Ai-π2-A structure from the reference dye M1, which has the D-π1-π2-A structure. By inserting different auxiliary acceptors Ai (i = 1–7) between the π1 and π2 onto the reference dye M1, we obtained the designed dyes to study their photovoltaic properties for use in DSSC devices. The geometrical structures, absorption spectrum properties, nonlinear optical properties (NLOs), energy levels, frontier molecular orbitals, and some photovoltaic parameters were theoretically investigated using density function theory (DFT) and time-dependent DFT (TD-DFT) methods, with the aim of improving the DSSC performance of the designed dyes. The theoretical results reveal that the designed dyes would be used as potential sensitizers in DSSCs due to their very small energy gaps, broad absorption spectra, higher NLO properties, lower reorganization energy (λtot), lower regeneration driving force (ΔGreg), longer excited lifetime (τ), higher vertical dipole moment (µnormal), reasonable electron injection driving force (∆Ginj), and equally reasonable light-harvesting efficiency (LHE) compared to the reference dye M1. Furthermore, the designed dyes (M2–M8) have better charge transferability, the highest stabilization energy, and the highest ability of electron-donating and electron-accepting, resulting in a high short-circuit current and better power conversion energy (PCE) compared to reference dye M1. These results show that the introduction of different auxiliary acceptors Ai can most effectively improve the photovoltaic performance of our system. [ABSTRACT FROM AUTHOR]

Some adsorbent hydrogels made of natural polymeric materials have not yet met the needs for a high level of wastewater purification. In the present study, a novel and environmentally friendly process is described for the production of natural cellulose-based metal oxide nanoparticle hydrogel beads. Recyclable adsorbent components include wastepaper-derived cellulose fiber, metal oxide nanoparticles and polyvinyl alcohol was synthesized, the WCF/PVA MO NP hydrogel beads were synthesized by using cross-linking agents (Ca2+, boric acid and NaCl), and were analyzed by evaluating their ability to remove the acid red 18 (AR18) from aqueous solution. The WCF/PVA MO NP was characterized by FESEM, XRD, EDX, BET, and FTIR. The results revealed that the metal oxide nanoparticles distributed on external and internal channels of the 3D fiber network of WCF with strongly covalent/non-covalent cross-linking bonds would facilitate mass diffusion and enhance the interaction between AR18. The results shown that more than 87.62% of AR18 was removed and adsorption capacity was 88.65 mg·g−1 under optimized conditions ([AR18]: 10 mg·L−1; [adsorbent]: 0.55 g·L−1; pH: 3; Time: 46 min). Results shown that the adsorption kinetics fit the pseudo-second-order model (0.99), and the adsorption isotherms fitted to Langmuir isotherm model (0.99). [ABSTRACT FROM AUTHOR]

Hydrogen titanate (H2Ti3O7) nanotubes, synthesized via the hydrothermal process, are one of the advanced adsorbents used for the treatment of aqueous solutions containing harmful organic dyes. Although various advanced oxidation processes (AOPs) have been demonstrated to regenerate the H2Ti3O7 nanotubes, an ozonation (O3)-based AOP still remains unexplored for this purpose. Hence, in the present work, this technique has been demonstrated, for the first time, to regenerate the H2Ti3O7 nanotubes after the adsorption of cationic methylene blue molecules on their surfaces from an aqueous solution. The effect of various test parameters, such as the O3 flow rate (2–6 g h−1), an ozonation time (10–60 min), and an initial regeneration solution pH (2–10), on the regeneration efficiency of ozonation-based AOP has been systematically investigated. The O3 flow rate, ozonation time, and initial regeneration solution pH of 6 g h−1, 60 min, and 6.6 (neutral) respectively have been observed to be the most optimum values for the complete regeneration of H2Ti3O7 nanotubes. The mechanism of the regeneration of nanotubes via an ozonation-based AOP has been ascertained by using the hydroxyl (●OH) and superoxide (O2●−) radical-trapping as well as the hydroperoxyl (●OOH) radical-scavenging experiments which unambiguously reveal that the ●OOH radicals, having a lower oxidation potential, are primarily responsible for the regeneration of H2Ti3O7 nanotubes. Five consecutive regeneration cycles of H2Ti3O7 nanotubes have been demonstrated which confirms that the high adsorption capacity of H2Ti3O7 nanotubes is maintained even after the repeated number of adsorption cycles which suggests the consistency of ozonation-based AOP. [ABSTRACT FROM AUTHOR]

The importance of water for all living organisms is unquestionable and protecting its sources is crucial. In order to reduce water contaminants, like toxic metals and organic dyes, researchers are exploring different techniques, such as adsorption, photocatalytic degradation, and electrolysis. Novel materials are also being sought. In particular, biopolymers like guar gum and xanthan gum, that are eco-friendly, non-toxic, reusable, abundant and cost-effective, have enormous potential. Gum-based nanocomposites can be prepared and used for removing heavy metals and colored dyes by adsorption and degradation, respectively. This review explains the significance of gum-based nanomaterials in waste water treatment, including preparative steps, characterization techniques, kinetics models, and the degradation and adsorption mechanisms involved. [ABSTRACT FROM AUTHOR]

We synthesized a γ-irradiated chitosan-ZnO-AgNPs (ICZA) composite by using a simple hydrogels method. We evaluated its adsorption/photocatalytic degradation abilities for the removal of an organic dye and its antibacterial activity. The XRD, SEM, TEM, EDS, and FTIR techniques were used to characterize the obtained samples. Based on the adsorption and degradation of methylene blue (MB) in the dark and under UV light irradiation, the adsorption and the photocatalytic activity of the as-obtained samples were evaluated. The optimum conditions for synthesizing the composite were as follows: contact time of 210 min, a dosage of 2 g/L, MB concentration of 40 mg/L, and a solution pH of 8.0. The ICZA had a high adsorption capacity, which was suitable for removing MB from the aqueous solutions; it showed a maximum adsorption capacity (qm) of 92.59 mg/g. The fit of the adsorption isotherms with the Langmuir model was satisfactory. The photocatalytic degradation ability of the composite was also better than that of other catalysts in the presence of UV light, with an apparent rate constant (kapp) of 3.08 × 10−2. The synthesized ICZA also showed good antibacterial activity against Staphylococcus aureus, with a minimum inhibitory concentration (MIC) and a minimum bactericidal concentration (MBC) of 12.5 g/mL and 50 g/mL under light-incubation and dark-incubation conditions. Finally, we discussed the hypothesized mechanism of the adsorption/photocatalytic activity and antibacterial activity of the ICZA composite in this study. [ABSTRACT FROM AUTHOR]

In this work, successful nanocomposites composed of different ratios of reduced graphene oxide and copper sulphide (xCuS–rGO) were fabricated to aid in treating water contaminated with organic dyes. XRD, TEM, SEM, XPS, IR, EDX and BET were applied for the characterization of (CuS–rGO). The photocatalytic strength of the prepared nanocomposites was evaluated using artificial sunlight irradiation. The nanocomposites were tested for their ability to degrade both anionic and cationic organic dyes, including amaranth and rhodamine B (RhB). The excellent photocatalytic strength of our composites, relative to pristine CuS and rGO, was interpreted as rGO sheets being very porous. In addition, the charge moved efficiently from rGO to CuS. The combined properties enhanced the efficiency of photodegradation of CuS–rGO composite across the dyes under the illumination of simulated sunlight. The electron transportation from rGO sheets to the CuS conduction band enhances the charge separation and transportation. The role of superoxide radicals in photocatalytic degradation was unveiled and the interactions between the studied dyes and our catalysts were investigated by density functional theory study and scavenging investigation. This work gives new ideas about the preparation and properties of (CuS–rGO) composites and their broad application in solving environmental problems. [ABSTRACT FROM AUTHOR]

Dispersion of colloidal particles in water or oil is extensively desired for industrial and environmental applications. However, it often strongly depends on indispensable assistance of chemical surfactants or introduction of nanoprotrusions onto the particle surface. Here we demonstrate the omnidispersity of hydrophilic-hydrophobic heterostructure particles (HL-HBPs), synthesized by a surface heterogeneous nanostructuring strategy. Photo-induced force microscopy (PiFM) and adhesion force images both indicate the heterogeneous distribution of hydrophilic domains and hydrophobic domains on the particle surface. These alternating domains allow HL-HBPs to be dispersed in various solvents with different polarity and boiling point. The HL-HBPs can efficiently adsorb organic dyes from water and release them into organic solvents within several seconds. The surface heterogeneous nanostructuring strategy provides an unconventional approach to achieve omnidispersion of colloidal particles beyond surface modification, and the omnidispersible HL-HBPs demonstrate superior capability for dye recycle merely by solvent exchange. These omnidispersible HL-HBPs show great potentials in industrial process and environmental protection. Dispersion of colloidal particles in water or oil is desired for industrial and environmental applications but it often strongly depends on indispensable assistance of chemical surfactants or introduction of nanoprotrusions onto the particle surface. Here, the authors demonstrate the omnidispersity of hydrophilic-hydrophobic heterostructure particles, synthesized by a surface heterogeneous nanostructuring strategy. [ABSTRACT FROM AUTHOR]

Advance the photo-activity of the nano-sized ZnO photocatalyst is an essential factor in remediation of environmental pollution caused by industrial-organic dyes. Blends of transition elements including Mn, Fe and Co ions were employed to modify the energy gap and the visible absorption state tail of ZnO as well as inhibit the charge carriers recombination by their flexible oxidation states. Five nanocatalysts composed of ZnO, Zn0.97Mn0.015Fe0.015O, Zn0.97Mn0.015Co0.015O, Zn0.97Fe0.015Co0.015O and Zn0.97Mn0.01Fe0.01Co0.01O were simply synthesized. All the prepared compositions have a single phase of ZnO wurtzite structure. Both compositions of Zn0.97Fe0.015Co0.015O and Zn0.97Mn0.01Fe0.01Co0.01O have high sensitive responses to visible light spectrum owing to band gap reduction and formation of absorption state tails. The SEM images demonstrated that the kind of the transition metal blends added to ZnO powder have a significant effect on its morphology. Remarkably, the addition of (Fe, Co) mixture to ZnO powder leads to formation of homogenous rods structure besides very fine spherical particles. All modified ZnO samples revealed enhanced photocatalytic activity but Zn0.97Fe0.015Co0.015O powder possesses the greatest efficiency (98%) for 25 ppm Reactive Yellow 145 dye in 75 min of solar illumination with acceptable stability. In addition, Zn0.97Fe0.015Co0.015O catalyst revealed high photo-removal activity for 25 ppm Rhodamine B and malachite green with measured efficiencies of 94 and 91% in 75 min, respectively. The suitable catalyst dose was identified to be 0.04 g (100 mL solution) and the main effective radicals are the hydroxyl (·OH) species. [ABSTRACT FROM AUTHOR]

This study proposes a new method for producing α-Fe2O3–CuO nanocatalyst that is both cost-effective and ecologically benign. The α-Fe2O3–CuO nanocomposite was prepared via moderate thermal oxidative decomposition of copper hexacyanoferrate. Its structure and surface morphology are affirmed via XRD, SEM, FTIR, EDX, TEM, XPS, and VSM. In the presence of H2O2, α-Fe2O3–CuO is employed as a heterogeneous catalyst to stimulate thermally induced degradation of dyes such as direct violet 4, rhodamine b, and methylene blue. The synergistic effect of Fe2O3 and CuO enhanced the catalytic activity of the nanocomposite compared to Fe2O3 and CuO separately. The effectiveness of DV4 degradation is optimized by evaluating multiple reaction parameters. The reaction rate increased substantially with the temperature, revealing its key role in the degradation process. Higher H2O2 levels and the inclusion of inorganic anions like chloride or nitrate also sped up the degradation process. While sulfate and humic acid, particularly at high doses, slowed it. The mechanism of H2O2 activation on α-Fe2O3–CuO is studied. The measurements of chemical oxygen demand and total organic carbon indicate that all dyes are highly mineralized. The remarkable performance and stability of this nanocomposite in removing diverse dyes render it a promising option for wastewater remedy. [ABSTRACT FROM AUTHOR]

This paper proposes a simple and environmentally friendly method for the green synthesis of SnO2–ZnO/bentonite nanocomposite in the presence of Acroptilon repens flower extract as a reducing and stabilizing agent. The synthesized nanocomposite was characterized using various techniques to investigate their structural properties and morphology. The photocatalytic degradation of the organic dye, eriochrome black-T (EBT) under solar irradiation and in the presence of synthesized nanocomposite was investigated. The results indicated that the nanoparticles were well immobilized onto bentonite as a support with minimum agglomeration. Moreover, the results of photocatalytic reactions showed that SnO2–ZnO/bentonite nanocomposite could remove the dyes in just 2.5 h and the degradation efficiencies approached 100% indicating the excellent performance of the catalyst. The kinetic study revealed that degradation of EBT in presence of the SnO2–ZnO/bentonite nanocomposite obeys first-order kinetics with the rate constant of 1.75 × 10–2 min−1. Furthermore, the biosynthesized nanocomposite exhibited a stable performance and high tolerance to the reaction conditions and was reused in three cycles with negligible loss of activity. [ABSTRACT FROM AUTHOR]

Present study reports the hydrothermal synthesis procedure to prepare the facile and sustainable orthorhombic Molybdenum trioxide (α-MoO3) nanoparticles (NPs) for the degradation of thymol blue dye. Synthesized α-MoO3NPs was characterized by FTIR, XRD, Zeta-potential, SEM, and TEM to investigate the functionalities, texture, size, and morphology of α-MoO3 NPs. The average size was calculated up to 68 ± 5 nm. The α-MoO3NPs was successfully applied to degrade toxic organic dye (thymol blue) in aqueous media. To achieve maximum percentage degredation of dye different parameters were optimized, including a catalyst dose, reaction time, effect of microwave irradiation at low power, reproducibility of catalyst. At optimum conditions, the fabricated α-MoO3NPs-based heterogeneous nano-catalyst was highly efficient for degrading thymol blue dye in aqueous media; the percentage degradation was obtained up to 99% within 60 s just using 120 µg of α-MoO3NPs was used under the microwave radiations. The heterogeneous nano-catalyst shows excellent performance and is highly efficient as compared to previously reported work. The schematic diagram for the degradation of thymol blue dye using prepared MoO3 nano-catalyst [ABSTRACT FROM AUTHOR]

Results of studying features of spinel structure formation in the CoO–Fe2O3 system obtained using various production techniques are presented. The possibility of forming cobalt (II) ferrite at the surface of a number of carriers is considered. It is shown that depending upon structural characteristics of the substrate, the cobalt (II) ferrite formed has different dispersion and degree of reversibility. It is established that increased catalytic activity in the process of purification of an aqueous solution from an organic dye during hydrogen peroxide breakdown of synthesized materials with an organic carrier has been established. [ABSTRACT FROM AUTHOR]

In this study, a green and effective adsorbent of chitosan/montmorillonite/algae (CHI/MMT/ALG) composite was developed to be an alternative adsorbent to remove dyestuffs including basic green 1 (BG1) and reactive blue 19 (RB19) from the aqueous solutions. The physicochemical characteristics of CHI/MMT/ALG were analyzed using XRD, CHN–O, BET, FTIR, pHpzc, and SEM analytical techniques. The findings of the characterization revealed that the increased surface functionalities offered an enticing platform for the improved adsorption of cationic and anionic dye molecules. The essential adsorption variables, such as A: CHI/MMT/ALG dosage (0.02–0.08 g), B: pH (4–9), and C: duration (5–30 min), were optimized using the Box-Behnken design (BBD) approach. The BG1 adsorption process demonstrated a better match with the Langmuir model, whereas the RB19 adsorption process exhibited a better fit with both the Temkin and Langmuir models. The fitting of the kinetic analysis illustrates that the BG1 and RB19 adsorption by CHI/MMT/ALG could be better represented by a pseudo-second-order model. The maximum adsorption capacity of CHI/MMT/ALG for BG1 and RB19 was specified to be 509.5 mg/g and 227.9 mg/g, respectively. The endothermicity and spontaneity of the BG1 and RB19 adsorption processes are evidenced by thermodynamic analysis. The improved surface functionalities of CHI/MMT/ALG inspired the adsorption mechanism of CHI/MMT/ALG for BG1 and RB19 could be essentially ascribed by electrostatic attraction, n-π stacking, and hydrogen bonding. Overall, the study's findings indicate that the newly developed CHI/MMT/ALG has significant potential for the removal of synthetic dye from aqueous. [ABSTRACT FROM AUTHOR]

The disposal of textile pollutants tainted by soluble organic dyes into the water without proper treatment may adversely impact the aquatic environment, humans, plants, and animals due to their toxic nature. As a result, the goal of this work is to look into the adsorptive removal of Eriochrome Black T (EBT) dye (as a model of soluble anionic organic dyes) from aqueous solution using a green synthesis nanoporous activated carbon @ Aluminum based metal–organic frameworks (AC@Al-MOFs) from a lemon peel waste as an inexpensive biosorbent. The physicochemical properties of Al-MOF and AC@Al-MOF composite were characterized by X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FTIR), Brunauer–Emmett–Teller (BET), scanning electron microscopy (SEM), and the impact of varied parameters on adsorption efficiency of Eriochrome Black T (EBT) including pH, dye concentrations, contact time and adsorbent dose, was examined. The experimental isotherms data were analyzed using Langmuir and Freundlich isotherm equations. The best fit was obtained by the Langmuir model with high correlation coefficients (R2 = 0.9976) with a maximum monolayer adsorption capacity of 303.0 mg/g. The results suggest that AC@Al-MOF composite is a potential choice for removing EBT dye molecules from aqueous media. [ABSTRACT FROM AUTHOR]

The enhanced photocatalytic process of GMNT NCs was achieved by wet impregnation. The resulting sample was examined using numerous analytical techniques to determine its composition, morphology, structure, and optical properties. GMNT photocatalyst showed impressive photocatalytic degradation efficiency (91.75%) over RhB dye in 100 min, when exposed by visible illumination. The photoreaction rate constant of GMNT ternary PCs (0.0233 min−1) was 6.2 times faster than bare GCN (0.0037 min−1), GMS (0.0055 min−1), and GCNT (0.0124 min−1) against RhB dye. Besides, they have considerable stability against RhB dye degradation after five cycles. A trapping experiment with a variety of scavengers also reveals that photogenerated charge carriers hole pair and ⋅O2− radicals play a prominent role in the photodegradation process. GMNT nanocomposite has been shown to enhance photocatalytic performance by suppressing e−–h+ pair separation and recombination efficiency. Hence, GMNT PCs have shown high potential for various environmental applications, including wastewater treatment. [ABSTRACT FROM AUTHOR]

The generation of electricity using solar energy is an effective system to overcome the current global energy crisis. In this regard, developing new semiconductor materials can be of great interest in overcoming the challenge of charge carrier recombination and, hence, improving the power conversion efficiency (PCE) in photovoltaic devices, particularly dye-sensitized solar cells (DSSCs). Here, reduced graphene oxide-Sr0.7Sm0.3Fe0.6Co0.4O3 (RGO-SSFC) nanocomposites were synthesized using the hydrothermal method and characterized with the aid of microscopic and spectroscopic techniques, as well as a vibrating sample magnetometer, and further tested for application as photoanodes in DSSCs. Scanning electron microscopy revealed the presence of RGO nanosheets that were fully decorated by irregular- and spherical-shaped SSFC nanoparticles. Fourier-transform infrared spectroscopy confirmed the strong synergistic interaction of the RGO-SSFC nanocomposites. The large surface area of RGO-SSFC nanocomposite photoanodes facilitated effective dye loading, high photon absorption, and efficient electron transfer, resulting in better device performance. Compared to RGO-SSFC-0.1 and RGO-SSFC-1.0, the RGO-SSFC-0.5 nanocomposite showed an enhanced open-circuit voltage (Voc) of 0.84 V, short-circuit current density (Jsc) of 14.02 mA cm−2 , and a PCE of 7.25%. Eosin B and MK-2 organic dyes used as photosensitizers coated on the RGO-SSFC semiconductors resulted in low-cost DSSC photoanodes. [ABSTRACT FROM AUTHOR]

Water pollution caused by organic dyes is one of the greatest threats to the ecosystem. The removal of dyes from water has remained a challenge for scientists. Recently, metal sulphides have emerged as a potential candidate for water remediation applications. The efficient charge transportation, greater surface-active sites, and low bandgap of metal sulphides make them an excellent choice of semiconductor photocatalysts for degradation of dyes. This review summarises the potential application of metal sulphides and their heterojunctions for the photocatalytic degradation of organic dyes from wastewater. A detailed study has been presented on the synthesis, basics of photodegradation and heterojunctions and photocatalytic activity. The effect of the use of templates, doping agents, synthesis route, and various other factors affecting the photocatalytic activity of metal sulphides have been summarised in this review. The synthesis techniques, characterisation techniques, mechanism of degradation of organic dyes by Z-scheme heterojunction photocatalyst, reusability and stability of metal sulphides, and the scope of future research are also discussed. This study indicates that Scopus-based core gathered data could be used to give an objective overview of the global dye degradation research from 2008 to 2023 (15 years). All data (articles, authors, keywords, and publications) is compiled in the Scopus database. For the bibliometric study, 1962 papers relevant to dye photodegradation by sulfide-based photocatalysts were found, and this number rises yearly. A bibliometric analysis provides a 15-year evaluation of the state-of-the-art research on the impact of metal sulfide-based photocatalysts on the photodegradation of dyes. [ABSTRACT FROM AUTHOR]

Due to its small particle size, high specific surface area, functional capability and long-term stable fluorescence, nanodiamond (ND) has been widely used in biomedical applications including fluorescent probes, drug delivery and biological imaging. Nevertheless, the metabolism of ND and its derivatives is not yet well understood for diverse biomedical applications. In this study, to evaluate the cytotoxicity and biodistribution of the ND derivative, pure ND was functionalized with ethylenediamine (EDA) as a linker (ND-EDA) and then covalently labeled with an organic fluorescent dye called calcein. The modified ND is referred to as ND-EDA-calcein. Even at the maximum dose of 0.1 mg·mL−1, the in vitro results for ND-EDA-calcein against HepG2 and LO2 cell lines showed negligible cytotoxicity, which was in line with the in vivo observations. In addition, it was found that following an intraperitoneal injection, ND-EDA-calcein could be accumulated mostly in the liver and kidney of the mice but not in the spleen. It is interesting to note that after 5 days following intraperitoneal injection, mice can totally metabolize the elimination of ND-EDA-calcein outside of their bodies. Therefore, our findings suggested that NDs can be considered for various nanomedicine applications including drug delivery and biomarkers. [ABSTRACT FROM AUTHOR]

There has been a lot of attention on water pollution by dyes in recent years because of their serious toxicological implications on human health and the environment. Therefore, the current study presented a novel polyethylene glycol-functionalized graphene oxide/chitosan composite (PEG-GO/CS) to remove dyes from aqueous solutions. Several characterization techniques, such as SEM, TEM, FTIR, TGA/DTG, XRD, and XPS, were employed to correlate the structure–property relationship between the adsorption performance and PEG-GO/CS composites. Taguchi's (L25) approach was used to optimize the batch adsorption process variables [pH, contact time, adsorbent dose, and initial concentration of methyl orange (MO)] for maximal adsorption capacity. pH = 2, contact time = 90 min, adsorbent dose = 10 mg/10 mL, and MO initial concentration = 200 mg/L were found to be optimal. The material has a maximum adsorption capacity of 271 mg/g for MO at room temperature. With the greatest R2 = 0.8930 values, the Langmuir isotherm model was shown to be the most appropriate. Compared to the pseudo-first-order model (R2 = 0.9685), the pseudo-second-order model (R2 = 0.9707) better fits the kinetic data. Electrostatic interactions were the dominant mechanism underlying MO sorption onto the PEG/GO-CS composite. The as-synthesized composite was reusable for up to three adsorption cycles. Thus, the PEG/GO-CS composite fabricated through a simple procedure may remove MO and other similar organic dyes in real contaminated water. [ABSTRACT FROM AUTHOR]

The limited signal of long-wavelength near-infrared-II (NIR-II, 900–1880 nm) fluorophores and the strong background caused by the diffused photons make high-contrast fluorescence imaging in vivo with deep tissue disturbed still challenging. Here, we develop NIR-II fluorescent small molecules with aggregation-induced emission properties, high brightness, and maximal emission beyond 1200 nm by enhancing electron-donating ability and reducing the donor-acceptor (D-A) distance, to complement the scarce bright long-wavelength emissive organic dyes. The convincing single-crystal evidence of D-A-D molecular structure reveals the strong inhibition of the π-π stacking with ultralong molecular packing distance exceeding 8 Å. The delicately-designed nanofluorophores with bright fluorescent signals extending to 1900 nm match the background-suppressed imaging window, enabling the signal-to-background ratio of the tissue image to reach over 100 with the tissue thickness of ~4–6 mm. In addition, the intraluminal lesions with strong negatively stained can be identified with almost zero background. This method can provide new avenues for future long-wavelength NIR-II molecular design and biomedical imaging of deep and highly scattering tissues. To achieve high-contrast in fluorescence imaging of deep tissues is challenging. Here, the authors develop NIR-II fluorescent small molecules with high brightness and emission extending to 1900 nm, enabling in vivo imaging of deep tissues with enhanced signal-to-background ratios. [ABSTRACT FROM AUTHOR]

In this study, the chemical pechini sol-gel method was used for the simple fabrication of Fe0.5Mn0.5Co2O4/Fe2O3 as a new nanocomposite at 400, 600, 800, and 1000 oC. The fabricated products at 400, 600, 800, and 1000 oC were encoded as E400, E600, E800, and E1000, respectively. The fabricated nanocomposites were identified using several devices such as XRD, N2 adsorption/desorption analyzer, FT-IR, EDS, UV–Vis diffuse reflectance spectrophotometer, and field emission scanning electron microscopy. The average crystallite size of the E400, E600, E800, and E1000 products is 80.31, 123.25, 130.75, and 141.36 nm, respectively. The FE-SEM showed that the E400 sample consists of rods, spheres, and irregular forms with an average diameter of 337.50 nm. Also, the E600 and E800 products consist of spheres and irregular shapes with an average diameter of 446.96 and 854.52 nm, respectively. Besides, the E1000 product comprises of cubic, sphere, and irregular shapes with a mean diameter of 1019.88 nm. The synthesized nanocomposites were used for the efficient photocatalytic degradation of safranin dye. In the presence of H2O2, 0.1 g of the synthesized nanocomposites completely decompose 50 mL of about 25 mg/L of safranin dye at pH equals 8 in 25 min. [ABSTRACT FROM AUTHOR]

This is due to the fact that TiO2 has the wide energy gap and short life and its photocatalytic active only under ultraviolet light, and so its application is greatly limited. TiO2 can form a heterojunction if combined with other semiconductors to enhance its photocatalytic ability under visible light. In this study, a TiO2/Bi2SiO5 photocatalyst with n–n heterojunction was successfully synthesized by the sol–gel method and hydrothermal method. Eggshell waste has long been used as fertilizer to grow plants or food additives for livestock, or as an adsorbent in metal ions and organic dyes. Using eggshell as a carrier of photocatalyst can possibly reduce its cracking of the substrate. The photocatalyst was deposited on eggshell powder by solid state dispersion (SSD). It was analyzed for the adsorption and degradation of methylene blue by various compositions of the photocatalysts and eggshell powder under visible light. The results demonstrated that the ratio of TiO2/Bi2SiO5: eggshell powder at 1:1 could have the best removal ability. To better facilitate the recovery of the photocatalyst from the aqueous solution, we used the techniques of electrostatic spraying and electrospinning to prepare nylon 6,6 nanofiber membranes with various composite photocatalyst (TiO2/Bi2SiO5/Eggshell/Nylon 6,6 NFM). The nanofiber membrane degraded 98% of methylene blue after 30 min of dark adsorption and 1 h of visible light irradiation. [ABSTRACT FROM AUTHOR]

Context: The organic solar cells (OSCs) are being developed with the goal of improving their photovoltaic capabilities. Here, utilizing computational methods, six new nonfullerene acceptors (NFA) comprising dyes (A1–A6) have been created by end-group alterations of the Y123 framework as a standard (R). Methods: The DFT-based investigations at B3LYP/6-31G + (d,p) level were applied to evaluate their properties. The planar geometries associated with these structures, which lead to improved conjugation, were validated by the estimation of molecular geometries. Dyes A1–A6 have shorter Egap than R, according to a frontier molecular orbital (FMO) investigation, which encourages charge transfer in them. The dyes with their maximum absorption range were shown by optical properties to be 692–711 nm, which is significantly better than R with its 684 nm range. Their electrostatic and Mulliken charge patterns provided additional evidence of the significant separation of charges within these structures. All the dyes A1–A6 had improved light harvesting efficiency (LHE) values as compared to Y123, highlighting their improved capacity to generate charge carriers by light absorption. With the exception of dye A4, all newly developed dyes might have a superior rate of charge carrier mobility than R, according to reorganization energies λre. Dyes A3 and A4 had the greatest open-circuit voltage (Voc). Dye A3 exhibited improvement in all of its examined properties, making it a promising choice in DSSC applications. [ABSTRACT FROM AUTHOR]

Context: Since 1991 when Grätzel et al. improved the conversion efficiency of dye-sensitized solar cells to 7.1% by applying nano technology as the first time, the researches on dye-sensitized solar cells have received widely attentions. The organic dye without precious metals has a lower cost, which is easily to get synthesized and its structure is easily decorated, owing a higher photoelectric conversion efficiency at the same time. Therefore, in recent years, the organic dye has attracted people's attentions more and more. In order to better understand the relationship between structure and properties of dye molecules, with ZL003 as a prototype, molecular modifications are then made and a scheme, with rigid fused π-bridge comprising electron-rich and deficient segments. The calculated results indicate that the π-bridge containing dithienopyrrolobenzothiadiazole and dipyrrolo-dithienobenzothiadiazole as π-bridge has been demonstrated to be successful to significantly redshift the absorption maximum wavelength, extend the lifetime of the first excited state, and decrease the energy gap between the highest occupied molecule orbital (HOMO) and the lowest unoccupied molecule orbital (LUMO). It is hoped that the calculation result of this paper would provide theoretical basis for the experimental synthesis of more efficient dye molecules. Method: All calculations were performed in Gaussian 09 program package. The ground state geometries (S0) and the first excited state (S1) were optimized using density function theory (DFT) with the hybrid function B3LYP functional, coupled with the 6-31G(d, p) basis set for optimization of molecule ground state conformations. TD-DFT calculations of excited state energies and absorption spectra were performed using MPWPW91 functional combined with the 6–31 + G (d) basis set. [ABSTRACT FROM AUTHOR]

Using a combination method of roasting process with soda ash (Na2CO3) and hydrochloric acid leaching, a TiO2-based photocatalyst was successfully synthesized from Indonesia ilmenite ore. The study investigated the effect of Na2CO3 ratios, roasting times, and HCl concentration on the physical and photocatalytic properties of the photocatalyst. The results revealed that HCl concentration played a critical role in altering the characteristics of the prepared photocatalyst. TiO2 composition increased by 61% compared to ilmenite ore when 20% HCl was used, whereas Fe2O3 composition decreased by 88%. The physical properties and photocatalytic activity of the prepared TiO2 were similar to those of low-grade commercial TiO2. When conducted to 3 h of low-power (8 W) UV light irradiation, the photocatalyst decomposed Eriochrome Black-T, an organic dye model pollutant, by up to 83%. This study's findings provide crucial implications for further research on recovering TiO2-based photocatalyst from ilmenite ore using a simple method. [ABSTRACT FROM AUTHOR]

Textile wastewater becomes the primary root of environmental pollution due to the rapid infection rates of freshwater, subsurface water, soil, and air. Due to the high absorption abilities of UV and visible light, polymer nanocomposite photocatalyst films (PNPFs) are recognized as potential candidates for textile wastewater treatment. Here, we developed novel cobalt monoxide (CoO)/polyaniline (PANI) PNPFs with high photocatalytic efficiency and stability. The photocatalytic efficiencies of PANI/CoO films were estimated utilizing the degradation of organic dyes and real-textile wastewater (RTW) under various lighting conditions. PANI/CoO PNPF completely decomposed methylene blue and RTW samples in 30 and 45 min under UV light illumination, respectively. We found that the CoO nanoparticles doubled the PANI's photocatalytic decomposition rate. However, under visible light irradiation, their photocatalytic efficiencies almost halved. Moreover, PANI/CoO PNPF exhibited excellent photocatalytic stability by maintaining the photocatalytic performance for up to five cycles with over 95% removal efficiency. This study yielded an efficient and alternative polymer nanocomposite to decompose wastewater sources contaminated with various textile dyes and may be examined for industrial-scale applications in the future. [ABSTRACT FROM AUTHOR]

The intent of this research work is to implement a biogenic, affordable, and highly effective Ce-Ni@biochar catalyst in order to study its photoactivity in the removal of crystal violet and malachite green oxalate. The catalyst was synthesized using liquid phase reduction method where cerium and nickel nanoparticles are embedded on the rice husk biochar for photocatalytic degradation of organic dyes in the presence of sunshine. Various characterization techniques were conducted on fabricated catalyst for adequate evaluation of the chemical composition as well as morphological and topographical properties of the formed compound. The nanoparticles embedded on biochar persuade increased charge separation that resulted in a substantial decrease in electron-hole recombination rate. The synergistic actions of the catalyst resulted in a high level of photocatalytic activity. The fabricated nanocatalyst showed excellent photoactivity that caused 96 and 99% degradation of crystal violet and malachite green oxalate, a growing industrial pollutant, within 35 and 25 min, respectively. A persuasive mechanism and kinetics are well presented. A series of investigations were done on other factors, such as contact duration, catalyst dosage, starting concentration, interfering ions, and pH, to know its degradation pursuance. The impacts of different water matrices were also investigated. The removal effectiveness of the synthesized catalyst persisted after five consecutive cycles. Marking the burgeoning industrial effluents as a result of rapid industrialization and also focusing on easy availability and low-cost source as well as high efficiency, reusability of the catalyst imparts its novelty and need of this research work. [ABSTRACT FROM AUTHOR]

For the first time an advanced carbon sorbent modified with salicylic acid for medicinal and veterinary applications was synthesized by the adsorption from solutions. Optimal parameters of the modification were determined: Solvent, "carbon sorbent–modifier" ratio, concentration of salicylic acid, equilibration time of the process in the "sorbent–salicylic acid solution" system, pH, and process temperature. The effect of the drying parameters on stability and amount of oxygen-containing groups on the carbon sorbent surface after modification was established. Physicochemical properties of the carbon sorbent and sorbents modified with different concentrations of salicylic acid were investigated: textural characteristics, qualitative and quantitative compositions of the surface functional groups, and amount of the deposited modifier. The possibility of salicylic acid desorption into the media simulating biological fluids, particularly the gastrointestinal medium, was explored. Adsorption characteristics of the carbon sorbent and sorbents modified with different concentrations of salicylic acid with respect to organic dyes—methylene blue and metanil yellow in a wide range of operating concentrations—were revealed. [ABSTRACT FROM AUTHOR]

This study presents a functional magnetic cellulose-based nanocomposite (mCNFAP/PMAA) to develop a highly efficient and sustainable adsorbent to remove organic dyes from an aqueous solution. Cellulose was extracted from Arenga Pinnata (AP) and was modified with 2,2,6,6-Tetramethyl-1-piperidinyloxy (TEMPO) to convert carboxyl end groups on cellulose chains that contribute to magnetization reaction. Methacrylic acid, an environmentally friendly monomer carrying carboxylic acid functional groups, was grafted on magnetic cellulose for effective cationic dye removal. The mCNFAP/PMAA nanocomposite structure was characterized by XRD, SEM/EDS, TGA, VSM, and FTIR. X-ray diffraction patterns indicated the successful extraction of cellulose from AP and the incorporation of the magnetic core. The SEM/EDS examinations referred to the existence of Fe3O4 nanoparticles and the grafting of PMAA on the surface of magnetic cellulose. At the same time, VSM results demonstrated that the saturation magnetization value of mCNFAP/PMAA was 15.5 emu/g, enabling the nanocomposite can be rapidly and easily separated from the aqueous solution under an external magnetic field. The adsorption and desorption behavior of mCNFAP/PMAA in batch and continuous lab-scale systems were evaluated using isotherm and kinetic models. The adsorption study revealed that the pH did not significantly affect on adsorption behavior of MB and the maximum adsorption capacity of mCNFAP/PMAA was 201 mg/g. The adsorption kinetic and isotherm models were well-fitted to the pseudo-second-order model and Langmuir isotherm. Notably, the regeneration performance of the mCNFAP/PMAA was excellent and protected its 75% capacity after the fifteenth adsorption/desorption cycle. The fixed column was used to determine the real-time behavior of the adsorbent in lab-scale continuous mode and the data were analyzed in models such as Thomas, Adams, and Yoon Nelson. The maximum adsorption capacity was found to be 264.65 mg/g. In conclusion, mCNFAP/PMAA composite is an effective and cheap material from sustainable sources. Due to its high regeneration and reusability capability, it could be employed as an effective adsorbent in removing pollutants from wastewater. [ABSTRACT FROM AUTHOR]

The small Ultra-Red Fluorescent Protein (smURFP) represents a new class of fluorescent protein with exceptional photostability and brightness derived from allophycocyanin in a previous directed evolution. Here, we report the smURFP crystal structure to better understand properties and enable further engineering of improved variants. We compare this structure to the structures of allophycocyanin and smURFP mutants to identify the structural origins of the molecular brightness. We then use a structure-guided approach to develop monomeric smURFP variants that fluoresce with phycocyanobilin but not biliverdin. Furthermore, we measure smURFP photophysical properties necessary for advanced imaging modalities, such as those relevant for two-photon, fluorescence lifetime, and single-molecule imaging. We observe that smURFP has the largest two-photon cross-section measured for a fluorescent protein, and that it produces more photons than organic dyes. Altogether, this study expands our understanding of the smURFP, which will inform future engineering toward optimal FPs compatible with whole organism studies. Researchers determined the three-dimensional structure of the small Ultra-Red Fluorescent Protein (smURFP) to understand its properties and the previous directed evolution process. In addition, they show smURFP fluoresces longer than small molecules. [ABSTRACT FROM AUTHOR]

The broad application of organic dyes such as 4-nitrophenol (4-NP), rhodamine 6G (R6G), and methylene blue (MB) as raw materials in the manufacture of dyes, explosives, pesticides, preservatives, and pharmaceuticals caused serious damage to the environment, particularly aquatic ecosystems. In this study, silver nanoparticles decorated ZnO/Fe3O4 (Ag/ZnO/Fe3O4) nanocomposite was used as a catalyst to reduce 4-NP, R6G, and MB in the presence of sodium borohydride as a reducing agent. Silver nanoparticles decorated ZnO/Fe3O4 composite was synthesized via a simple and inexpensive chemical reduction method. Scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), and X-ray diffraction (XRD) were used to characterize the particles. The surface-enhanced Raman spectroscopy (SERS) activity of the nanocomposites due to AgNPs was used to monitor catalytic reactions with detailed spectral features using SERS. Thus, the catalytic transformation of 4-nitrothiophenol (4-NTP) into 4-aminothiophenol (4-ATP) was traced using SERS. The magnetic property of the nanocomposites enables its repeated use. Easy recovery of the particles from the reaction solution was achieved and run for fifteen cycles with no significant loss of its efficiency. [ABSTRACT FROM AUTHOR]

Electrocoagulation was demonstrated for the effective removal of organic dyes, waxes, and sodium silicate from batik wastewater. For the first time, the reuse of an electrocoagulated batik sludge (EBS) by converting it into an adsorbent for Acid Red 18 (AR18) dye removal is reported. The EBS sample was dried in an oven to produce the raw EBS (REBS) adsorbent, which was then calcined to remove its organic constituents to give calcined EBS (CEBS) adsorbent. Nitrogen adsorption–desorption isotherm, scanning electron microscope-energy-dispersive X-ray (SEM–EDX), and Fourier transformed infrared (FTIR) analyses were applicable to reveal the adsorbents' physical and chemical characteristics. Effect of different preparation methods (REBS and CEBS), initial solution pH (3–9), adsorbent dosage (0.1–0.4 g/200 mL), initial concentrations (25–100 mg/L), and temperature (30–50 °C) on the adsorption of AR18 dye as well as regeneration and leaching study of the adsorbent were elucidated. The isotherm results indicated that the experimental data were best fitted to the Langmuir model with maximum adsorption capacity, qmax of 51.62 mg/g. Meanwhile, the adsorption of AR18 dye onto REBS mainly occurred through chemisorption as the kinetic data were best described by the pseudo-second-order model. REBS appeared to be a potential adsorbent for the removal of AR18 dye due to its simple preparation method, good adsorption capacity, and reusability performance. [ABSTRACT FROM AUTHOR]

In this study, reduced graphene oxide (RGO) with good water dispersibility and excellent adsorption performance was successfully prepared using sodium borohydride (NaBH4) as reductant, and their characterization and adsorption performance for Basic Red13 (BR13) and Cu2+ were analyzed. The results showed that RGO had an obvious graphene-like structure with the C/O ratio of 3.19, while the C/O ratio of graphene oxide (GO) was only 1.81. The reason for the good water dispersibility of RGO was the retention of partial oxygen-containing groups, especially carboxyl groups. The adsorption of RGO for BR13 and Cu2+ was typical monolayer physisorption, which could be well-described by pseudo-first-order and Langmuir isotherm models. The maximum adsorption capacities of RGO were 1674.01 mg/g for BR13 at pH = 13 and 164.72 mg/g for Cu2+ at pH = 6, which much higher than the corresponding values of 1258.65 mg/g and 123.14 mg/g for GO. In particular, the adsorption capacity of RGO for BR13 was the highest value reported so far. Moreover, no significant loss of adsorption performance was observed even after five cycles. This work suggested that reduced graphene oxide was an efficient adsorbent for the removal of organic dyes and heavy metal ions from water, which had great potential in pollution control applications. [ABSTRACT FROM AUTHOR]

The greener approaches for synthesis of triple junction nanostructured material consisting of NiO/ZrO/Mn3O4 mixed oxide provided an alternative way by lowering the hazardous chemicals utilization and diminishing biological risks in the biomedical applications. Plant-assisted synthesis of mixed metal oxide nanoparticles is now bulging because of its simplicity, rate of synthesis and environmental affability. The structural and morphological properties of synthesized nanocomposite were analyzed by various spectroscopic techniques including Fourier transform infrared spectroscopy, X-ray powder diffraction, Raman and field emission scanning electron microscopy coupled with energy-dispersive spectroscopy which confirmed the formation of pure NiO/ZrO2/Mn3O4 nanocomposites. The phytochemicals found in the leaf extract for the formation of metal oxide nanocatalysts were identified using Fourier transform infrared spectroscopy and gas chromatography–mass spectrometry. The organic complex (phytocompounds of leaf extract) plays an important role in the synthesis mechanism as well as in improving the catalytic efficiency of the material, as the organic functional groups incorporate electron and proton into the reaction mechanism. The study covers the effect of triple metal oxide nanoparticles size on the rate of degradation of hazardous dye (methyl orange). The nanoparticles were proved as an efficient candidate for the catalysis of organic dyes via the electron transfer process. The removal of methyl orange increased with time depicting excellent catalytic activity of the catalyst even under dark ambient conditions (84%). Moreover, the kinetics of catalytic reaction process based on composite (NiO/ZrO/Mn3O4) follows pseudo-first-order kinetics. [ABSTRACT FROM AUTHOR]

Water purification is considered one of the most essential issues in our lives. Therefore, the contamination of water surfaces owing to the hasty upsurge in industrialization has received great global attention because of its potential danger to human health and the eco-system. Particularly, the discharge of various non-biodegradable contaminants into the water body—heavy metal ions, organic dyes, pharmaceutical antibiotics, pesticides, and oils—causes these contaminants to accumulate on the water's surface and have harmful impacts on humans and the environment. Several conventional methods can be applied to solve this problem, including chemical oxidation, precipitation, coagulation, and so on. However, they suffer from serious limitations: high cost, limited functionality, prolonged and heavy energy use, and poor separation efficiency. Conversely, the adsorption technique has recently attracted a lot of attention for wastewater treatment thanks to its remarkable benefits of being a simple, highly selective, and low-cost technique. Recently, natural polysaccharides (especially starch)-based adsorbents have received great interest in water purification owing to their outstanding properties, including being easily available, non-toxic, low-cost, biodegradable, and biocompatible. However, it possesses notable drawbacks that prevent it from being used alone as an adsorbent for wastewater treatment, including low thermal stability, slight water solubility, and rapid degradability in water. Therefore, this review highlights a comprehensive presentation about various starch modifications: starch-based grafts, hydrogels, aerogels, beads, nanofibers, and nanocomposite formulations to remove several toxic contaminants, including toxic heavy metal ions, organic dyes, pharmaceutical antibiotics, pesticides, and oils. [ABSTRACT FROM AUTHOR]

In this work, a simple green method was followed to prepare ZrO2/ZnO/AC nanocomposite with the aid of plant extract as a capping and stabilizing agent for the nanoparticles. The prepared nanocomposite was characterized with different techniques such as Fourier transform infrared (FTIR), ultraviolet–visible spectroscopy (UV-Vis), dynamic light scattering (DLS), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), scanning electron microscope (SEM), thermal gravimetric analysis (TGA), and nitrogen adsorption for surface area. The successful formation of ZrO2/ZnO and loading it on the surface of activated carbon (AC) was confirmed by XRD, UV-Vis, EDS, and SEM images. Different degradation tests were performed under different conditions including the mass of the catalyst, pH, the concentration of dye solution and H2O2 used, and the catalyst. Blank tests ensured the necessity of both catalyst and H2O2 for the degradation to start. ZrO2/ZnO/AC was the best compared to ZrO2/ZnO, and AC with a degradation of 68% compared to 3% and 36%, respectively. The performance of ZrO2/ZnO was almost negligible confirming the importance of combining nanoparticles with suitable support. Furthermore, the highest degradation efficiency using ZrO2/ZnO/AC was achieved at a pH of 2 with degradation of 80% compared to 67% at a pH of 10, since the surface will be positively charged leading to a higher reaching rate of MO anions to the surface. Also, the highest performance was achieved when 0.8% of H2O2 was used with degradation of 91%. Despite the lower degradation in this work compared to what has been reported in the literature, it is still very promising since it was achieved under a stagnant and dark environment, which makes it a promising candidate for treating huge bodies of wastewater stored in dark places or containers. [ABSTRACT FROM AUTHOR]

The present study proposed the synthesis of low-toxicity and eco-friendly spherically shaped manganese oxides (α-MnO2, Mn2O3, and Mn3O4) by using the chemical precipitation method. The unique variable oxidation states and different structural diversity of manganese-based materials have a strong effect on fast electron transfer reactions. XRD, SEM, and BET analyses were used to confirm the structure morphology, higher surface area, and excellent porosity. The catalytic activity of as-prepared manganese oxides (MnOx) was investigated for the rhodamine B (RhB) organic pollutant with peroxymonosulfate (PMS) activation under the condition of control pH. In acidic conditions (pH = 3), complete RhB degradation and 90% total organic carbon (TOC) reduction were attained in 60 min. The effects of operating parameters such as solution pH, PMS loading, catalyst dosage, and dye concentration on RhB removal reduction were also tested. The different oxidation states of MnOx promote the oxidative–reductive reaction under acidic conditions and enhance the SO4•−/•OH radical formation during the treatment, whereas the higher surface area offers sufficient absorption sites for interaction of the catalyst with pollutants. A scavenger experiment was used to investigate the generation of more reactive species that participate in dye degradation. The effect of inorganic anions on divalent metal ions that genuinely occur in water bodies was also studied. Additionally, separation and mass analysis were used to investigate the RhB dye degradation mechanism at optimum conditions based on the intermediate's identification. Repeatability tests confirmed that MnOx showed superb catalytic performance on its removal trend. [ABSTRACT FROM AUTHOR]

Globally, treating and disposing of industrial pollutants is a techno-economic challenge. Industries' large production of harmful heavy metal ions (HMIs) and dyes and inappropriate disposal worsen water contamination. Much attention is required on the development of efficient and cost-effective technologies and approaches for removing toxic HMIs and dyes from wastewater as they pose a severe threat to public health and aquatic ecosystems. Due to the proven superiority of adsorption over other alternative methods, various nanosorbents have been developed for the efficient removal of HMIs and dyes from wastewater and aqueous solutions. Being a good adsorbent, conducting polymer-based magnetic nanocomposites (CP-MNCPs) has drawn more attention for HMIs and dye removal. Conductive polymers' pH-responsiveness makes CP-MNCP ideal for wastewater treatment. The composite material absorbed dyes and/or HMIs from contaminated water could be removed by changing the pH. Here, we review the production strategies and applications of CP-MNCPs for HMIs and dye removal. The review also sheds light on the adsorption mechanism, adsorption efficiency, kinetic and adsorption models, and regeneration capacity of the various CP-MNCPs. To date, various modifications to conducting polymers (CPs) have been explored to improve the adsorption properties. It is evident from the literature survey that the combination of SiO2, graphene oxide (GO), and multi-walled carbon nanotubes (MWCNTs) with CPs-MNCPs enhances the adsorption capacity of nanocomposites to a large extent, so future research should lean toward the development of cost-effective hybrid CPs-nanocomposites. [ABSTRACT FROM AUTHOR]

In this paper, nanocomposite NiO/Cr2O3 has been synthesized by a simple chemical reduction method to study its photocatalytic activity under sunlight irradiation. Various advanced analytical techniques including powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive spectroscopy (EDS), elemental mapping, Fourier transform infrared spectroscopy (FTIR), and UV-visible spectroscopy have been utilized to characterize the synthesized NiO/Cr2O3 nanocomposite. SEM images show the sheet-shaped morphology of NiO/Cr2O3 nanocomposite. These sheets have a rough surface with nano to micro size cracks. These cracks play important role in the enhancement of photocatalytic activity by increasing surface active sites for the adsorption of dye molecules on the surface of the photocatalyst. The organic dyes crystal violet (CV) and methylene blue (MB) have been chosen to study the photocatalytic behavior of NiO/Cr2O3 nanocomposite under sunlight irradiation. The photocatalytic efficiency of NiO/Cr2O3 nanocomposite has been obtained 88.47% and 93.63% against crystal violet and methylene blue respectively. The results of the photocatalytic kinetics exhibit that degradation rate constant value for crystal violet dye is higher as compared to methylene blue dye. Obtained kinetic results indicate that synthesized nanocomposite acts as an efficient photocatalyst for the degradation of both crystal violet dye and methylene blue dye. NiO/Cr2O3 nanocomposite also exhibited reusability and stability for photocatalytic degradation of both organic dyes. Photoelectrochemical measurements as photocurrent, electrochemical impedance spectroscopy (EIS), and Mott-Schottky plot were also performed for synthesized NiO/Cr2O3 nanocomposite. Consequently, this synthesized NiO/Cr2O3 nanocomposite can be utilized for environmental remediation of harmful dyes. [ABSTRACT FROM AUTHOR]

Fabrication of heterojunction semiconductors for the photodegradation of toxic organic dyes under sunlight exposure has earned significant recognition from researchers nowadays. On that account, we have synthesized and explored a comparative photodegradation study of ZnO/CuO nanocomposite with ZnO and CuO nanoparticles. ZnO and CuO nanoparticles have been synthesized by biosynthesis methods using Ficus benghalensis leaf extract. As-synthesized ZnO and CuO nanoparticles have been further utilized for the synthesis of ZnO/CuO nanocomposite by the mortar pestle crushing/milling method. Both biosynthesis methods and mortar pestle crushing/milling methods are simple, low-cost, and environmentally friendly. Structural, optical, and morphological analysis of all the synthesized nanomaterials have been done by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET), field emission scanning electron microscopy (FESEM), energy-dispersive spectroscopy (EDS), fourier transform infrared spectroscopy (FTIR), and UV–visible spectroscopy. PXRD data reveal that synthesized ZnO nanoparticles are in the hexagonal wurtzite phase, CuO nanoparticles in the monoclinic phase, and ZnO/CuO nanocomposite in the hexagonal wurtzite as well as in monoclinic phase. FE-SEM and TEM images of ZnO/CuO nanocomposite reveal the nanorod-shaped morphology along with micro-sized and nano-sized flakes. The BET analysis shows the surface areas 18.128 m2/g for ZnO nanoparticles, 16.653 m2/g for CuO nanoparticles, and 19.580 m2/g for ZnO/CuO nanocomposite, respectively. The energy band gap values of ZnO/CuO nanocomposite are obtained 3.13 eV for ZnO and 2.76 eV for CuO, respectively. The photocatalytic behaviors of all the synthesized nanomaterials are examined against aqueous dye solutions of methylene blue (MB), rhodamine B (RhB), and methyl orange (MO) under sunlight irradiation. The results reveal that the photocatalytic degradation efficiency of ZnO/CuO nanocomposite has been found higher than with ZnO and CuO nanoparticles for all the dyes. Also, all the synthesized nanomaterials indicate higher photocatalytic degradation efficiency for methylene blue dye among all three dyes. The kinetics of photodegradation of all the dye solutions has also been investigated in the presence of ZnO, CuO, and ZnO/CuO photocatalysts separately. The results exhibit that rate constant values for all the dyes are higher with ZnO/CuO nanocomposite than with ZnO and CuO nanoparticles. ZnO/CuO nanocomposite demonstrates degradation efficiency for MB dye 99.13%, for RhB 80.21%, and for MO 67.22% after 180 min of sunlight exposure. ZnO/CuO nanocomposite and ZnO and CuO nanoparticles also show the best reusability and stability up to three cycles for photocatalytic degradation of MB dyes among all the dyes. Therefore, green synthesized ZnO/CuO nanocomposite could be used as an efficient photocatalyst for the degradation of various toxic dyes. The mineralization of different dyes using ZnO/CuO nanocomposite has been examined by FTIR analysis. Furthermore, the mineralization of MB dye has been done by total organic carbon (TOC) measurements. [ABSTRACT FROM AUTHOR]

In the present study, we have synthesized magnesium oxide (MgO) nanoparticles by a facile and cost-effective chemical co-precipitation method with annealing at three different temperatures (350°C, 450°C, and 550°C) for the removal of various organic dyes. X-ray diffraction studies revealed that the prepared samples are having sizes below 20 nm and with pure phase. Phase transformation of hexagonal Mg(OH)2 nanoparticles to discretely cubical structured MgO nanoparticles has been observed with increasing the annealing temperatures which is also supported by the TGA/DSC analysis. Mg–O stretching vibration peaks in the range of 400–800 cm−1 obtained by FTIR spectroscopy support the formation of MgO nanoparticles. The observed Raman active bands for the annealed sample at 550°C confirm the formation of the nanocrystalline phase since these bands are typically absent in the bulk MgO as well as in Mg(OH)2. The surface morphology of the as-prepared Mg(OH)2 are aggregated nano-petals which changed into spherical shape for MgO annealed at 550°C as studied by field emission scanning electron microscopy (FESEM). The specific surface area of MgO nanoparticles annealed at 550°C using BET isotherms is found to be 37.487 m2g−1. The optical bandgaps of the prepared samples are found to be in the range of 4.4 to 5.1 eV using the Tauc plot. Adsorption studies with a variation of initial brilliant green dye concentration and contact time are carried out along with the studies of adsorption kinetic and isotherm models. Langmuir isotherm model is the most suitable model on the basis of correlation constant with maximum BG dye adsorption capacity onto MgO@550°C which is found to be 63.9 mg/g. The adsorption kinetics followed the pseudo-second-order model. Also prepared pristine MgO nanoparticles showed significant photocatalytic performance for the degradation of various dyes; brilliant green (BG: 88.91%), methylene blue (MB: 79.05%), crystal violet (CV: 76.49%), methyl orange (MO: 68.62%), and brilliant blue (BB: 40.44%) under visible irradiation. MgO nanoparticles could be a promising adsorbent and photocatalyst that may be employed in the treatment of effluents from industries. [ABSTRACT FROM AUTHOR]

The discharge of organic dye pollutants in natural water bodies has put forward a big challenge of providing clean water to a large part of the population. As the population is increasing with time, only underground water is not sufficient to complete the water requirements of everyone everywhere. Purification of wastewater and its reuse is the only way to fulfill the water needs. Nanotechnology has been used very efficiently for wastewater treatment via photocatalytic degradation of dye molecules. In the past few years, a lot of investigations have been done to enhance the photocatalytic activity of metal oxide semiconductors for water purification. In this review, we have discussed the different methods of synthesis of various metal oxide semiconductor nanoparticles, energy band gap, their role as efficient photocatalysts, radiations used for photocatalytic reactions, and their degradation efficiency to degrade the dye pollutants. We have also discussed the nanocomposites of metal oxide with graphene. These nanocomposites have been utilized as the efficient photocatalyst due to unique characteristics of graphene such as extended range of light absorption, separation of charges, and high capacity of adsorption of the dye pollutants. [ABSTRACT FROM AUTHOR]

In this work, Fe3O4/CoNi-MOF was synthesized by a simple solvothermal method. The catalytic performance of 0.2-Fe3O4/CoNi-MOF toward PMS activation was studied by degradation of 20 mg/L methylene blue (MB). The results indicated that 0.2-Fe3O4/CoNi-MOF had good catalytic ability, the removal rate of MB was 99.4% within 60 min with 125 mg/L PMS and 150 mg/L catalyst. Quenching experiment and electron paramagnetic resonance (EPR) analysis revealed that the singlet oxygen (1O2), superoxide radical (•O2−) and sulfate radical (SO4•−) played a crucial role in the catalytic degradation process. Meantime, mechanism of PMS activation by 0.2-Fe3O4/CoNi-MOF was proposed, the electrons donated by Fe2+ can also enhance the Co–Ni cycles. In conclusion, Fe3O4/CoNi-MOF composite catalyst has the advantages of simple preparation, excellent catalytic activity and reusability, which is an effective catalyst for water pollution control. [ABSTRACT FROM AUTHOR]

It is a great challenge to develop photocatalysts for the degradation of organic pollutants in the aqueous environment, especially those with excellent catalytic performance under visible light conditions. In this work, using graphene oxide (GO) as an electron shuttle agent and carrier, a hybrid of ZIF-8/NH2-MIL-125(Ti) and GO (ZIF-8/NH2-MIL-125(Ti)/GO) was prepared by a simple two-step solvothermal method. The morphology, structure, and combination of the synthesized catalysts were studied. The results showed that graphene oxide and ZIF-8 formed an in situ load on NH2-MIL-125(Ti). The construction of hybrid materials significantly improved the catalytic activity of NH2-MIL-125(Ti) in the visible light range. The degradation activity of the synthesized catalyst was further tested with reactive red dye. The results showed that the catalyst exhibited excellent catalytic removal efficiency for active red, with a degradation rate of 99.8% within 2 h. The prepared hybrid materials have good application prospects in the field of organic pollutant treatment in water. [ABSTRACT FROM AUTHOR]

In this paper, we present the first attempt to evaluate the role of carboxymethyl cellulose (CMC) as a chelating agent in the sol–gel auto-combustion method of producing barium hexaferrite (BaFe12O19). We also report the application of the system as a photocatalyst for dye degradation. The formation, morphology, and crystalline structure of the synthesized nanoparticles are determined using XRD, SEM, EDS, VSM, FTIR, and TEM techniques. High efficiency under visible light, with a band gap of 1.62 eV and a BET surface of 17.93 m2/g, has been observed for the BaFe12O19 catalyst. The operating parameters, such as reaction time, initial dye concentration, light intensity, reusability, and dye type, are studied. Degradation rates as high as 98.26% (Kapp = 0.082 min–1) and 89.07% (Kapp = 0.0743 min–1) were obtained for cases of methylene blue and malachite green under conditions of visible light irradiations when BaFe12O19 was used. The BaFe12O19 catalyst has been shown to exhibit a high degradation performance for cationic dyes. Furthermore, BaFe12O19 magnetic nanoparticles show excellent reusability for dye degradation because the photocatalyst did not exhibit a significant decrease in its activity even after five runs (81.56%). As a result, the current study confirmed that photocatalytic degradation was a promising technology for saving water and treating wastewater formed from textile dye industries. The technique can be used to study the efficiency of photocatalytic degradation and understand the process of recycling waste effluents under conditions of minimized water use. [ABSTRACT FROM AUTHOR]

A biogenic synthesis of Ag NPs adorned Helleborus niger extract-modified graphene oxidenanohybrid material has been demonstrated. Initially, the Helleborus niger extract was functionalized on the surface of graphene oxide. The polyphenolic groups of plant phytochemicals facilitated the green reduction of Ag ions as well as GO to afford the Ag/H.niger@rGO nanocomposite. The nanocomposite was characterized using FT-IR, FE-SEM, EDX, elemental mapping, TEM and XRDanalysis.Towards its application, it was found to be an efficient catalyst in the reductive degradation of toxic water pollutant organic dyes like Methylene blue (MB)and 4-nitrophenol (4-NP) over NaBH4 at room temperature. Time dependent UV–Vis spectroscopy was used to follow up the reactions which revealed that the reactions were completed within very short time (50–60 s). After the chemical applications we also explored the material biologically in the resistance of human colon cancer and thereby studied the cytotoxicity over two standard cell lines, HT-29 and Caco-2. The conventional MTT assay was carried out over them which revealed an increase in % cell viability dose dependently. In addition, DPPH radical scavenging test was performed for studying anti-oxidant activity. The IC50 values observed in the two cell lines were 368.2 μg/ml and 254.2 μg/ml respectively. [ABSTRACT FROM AUTHOR]

The present work aims to fabricate of graphene oxide (GO) nanosheets-yttrium oxide (Y2O3)–silicon oxide (SiO2) ternary nanostructures as high photo-degradation activity against pollutants of organic dyes. The GO nanosheets were added to Y2O3/SiO2 nanostructures with ratios 5%, 10% and 15%. The structural and photo-degradation characteristics of Y2O3/SiO2/GO nanostructures were studied. The structural characteristics included X-ray diffraction (XRD) and scanning electron microscope (SEM). Results of X-ray indicated that no reaction between components. SEM micrographs showed high distribution of GO nanosheets inside the Y2O3/SiO2 nanostructures. The photo-degradation against organic dyes improved from 1.17% for Y2O3/SiO2 nanostructures to 52% when the concentration of GO nanosheets reached 15 wt% at time (45 min). The dye concentration reduced with an increase in the nanomaterials content and irradiation time. Finally, the obtained results indicated that the Y2O3/SiO2/GO nanostructures have individual activity for photo-degradation of organic dyes which can be considered as key to remove the pollutants of organic dyes with elevated activity, short time, low nanomaterials concentration and few cost compared of others nanomaterials. [ABSTRACT FROM AUTHOR]

This article reports preparation of Bi2WO6 using solid-state and solution combustion methods. Different physicochemical characterization techniques such as XRD, SEM, TEM, BET-N2 adsorption study, UV–vis, XPS and photoluminescence spectroscopy were used to examine crystalline phase, optical and morphological properties of synthesized Bi2WO6 samples. The evaluation of prepared photocatalyst for methyl orange degradation, Cr(VI) reduction under visible light and rhodamine B degradation under direct sunlight was carried out. The sample prepared by a solution combustion route, exhibited superior photocatalytic activities than that prepared by a traditional solid-state route. [ABSTRACT FROM AUTHOR]