Search

The main objective of this study is to optimise a new composite for the depollution of contaminated water. This pollution can have adverse effects on both human health and the environment. The aim ...

Over more than three decades, the scientific community has been contentiously interested in structuring varying photocatalytic materials with unique properties for appropriate technology transfer. Most of the existing reported photocatalysts in the literature show pros and cons by considering the type of application and working conditions. Bismuth titanate oxides (BTO) are novel photocatalysts that raised recently towards energy and environmental-related applications. Most recent advances to developing bismuth titanate-based photocatalysts for the oxidation of organic pollutants in the water phase were reviewed in this report. To counter the potential drawbacks of BTO materials, i.e., rapid recombination of photoproduced charges, and further promote the photoactivity, most reported approaches were discussed, including creating direct Z-scheme junctions, conventional heterojunctions, metal/non-metal doping, coupling with carbon materials, surface modification and construction of oxygen vacancies. In the end, the review addresses the future trends for better engineering and application of BTO based photocatalysts towards the photodegradation of organic pollutants in water under controlled lab and large scales conditions.

Air pollution has become a significant challenge for both developing and developed nations. due to its close association with numerous fatal diseases such as cancer, respiratory, heart attack, and brain stroke. Over recent years, heterogeneous semiconductor photocatalysis has emerged as an effective approach to air remediation due to the ease of scale-up, ready application in the field, use of solar light and ready availability of a number of different effective photocatalysts. To date, most work in this area has been conducted using UV-absorbing photocatalysts, such as TiO2 and ZnO; However, recent studies have revealed Ag3PO4 as an attractive, visible-light-absorbing alternative, with a bandgap of 2.43 eV. In particular, this material has been shown to be an excellent photocatalyst for the removal of many types of pollutants in the gas phase. However, the widespread application of Ag3PO4 is restricted due to its tendency to undergo photoanodic corrosion and the poor reducing power of its photogenerated conductance band electrons, which are unable to reduce O2 to superoxide •O2 −. These limitations are critically evaluated in this review. In addition, recent studies on the modification of Ag3PO4 via combination with the conventional heterojunctions or Z-scheme junctions, as well as the photocatalytic mechanistic pathways for enhanced gas-pollutants removal, are summarized and discussed. Finally, an overview is given on the future developments that are required in order to overcome these challenges and so stimulate further research into this promising field.

In this work, the core–shell PANI@WO3 composite was obtained from the reaction of aniline monomer polymerization with WO3 particles; sodium persulfate was used as an oxidant. Various analytical techniques such as scanning electron microscopy (SEM-EDS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Brunauer–Emmett–Teller (BET), and X-ray photoelectron spectroscopy (XPS) were used to characterize the as-prepared PANI@WO3 adsorbent, which well confirmed that the WO3 particles were coated by polyaniline polymer. The PANI@WO3 composite was tested as an adsorbent to remove reactive orange G (OG) for the first time. pH, adsorbent dose, contact time, initial dye concentration, and temperature were systematically investigated in order to study their effect on the adsorption process. The experimental findings showed that the PANI@WO3 composite has considerable potential to remove an aqueous OG dye. Langmuir and Freundlich's models were used to analyze the equilibrium isotherms of OG dye adsorption on the PANI@WO3 composite. As a result, the best correlation of the experimental data was provided by the Langmuir model, and the maximum capacity of adsorption was 226.50 mg g 1. From a thermodynamic point of view, the OG dye adsorption process occurred spontaneously and endothermically. Importantly, PANI@WO3 still exhibited an excellent adsorption capability after four regeneration cycles, indicating the potential reusability of the PANI@WO3 composite. These results indicate that the as prepared PANI@WO3 composite could be employed as an efficient adsorbent and was much better than the parent material adsorption of OG dye

Herein, we report the preparation of a novel biosorbent; a citric acid modified red-seaweed for crystal violet (CV) removal from water. Surface characterization and basic biosorption characteristic...

Well-crystallized Ca3(PO4)2 doped and un-doped nano-particles with the maximum strontium content (40 wt% Sr) followed by calcination at 800 °C for 3 h were synthesized via facile co-precipitation method. DTA/TGA, X-ray diffraction (XRD), energy dispersive scanning electron microscopy (SEM/EDX), UV–vis diffuse reflectance spectrum (UV–vis DRS), Raman spectroscopy and photoluminescence (PL) techniques were used for material characterization. The (XRD) patterns of as-synthesized Sr-doped Ca3(PO4)2 solid solution samples exhibited a systematic shift toward lower angles by possessing a single rhombohedral crystal structure without any secondary phases. The UV light driven photocatalytic activity was assessed for rhodamine B (RhB) degradation. As a result, ultrafast photodegradation activity was observed after Sr doping. Moreover, the 30 wt% Sr-Ca3(PO4)2 sample showed the highest photocatalytic degradation among the Sr-doped Ca3(PO4)2 samples toward RhB. It was further suggested that as-synthesized 30 wt% Sr-Ca3(PO4)2 superior photocatalytic performance is ascribed to the more proficient partition of photogenerated electron-hole pairs. Furthermore, the involved mechanism of superior photocatalytic performance of the 30 wt% Sr-Ca3(PO4)2 solid solution was also investigated. In addition, regeneration cycles indicated the higher stability of the photocatalyst to be effectively recycled up to four times without any considerable reduction in photocatalytic performance. Thus, these informations further provides us a scalable pathway to fabricate Sr doped Ca3(PO4)2 and its consequent use as an efficient photocatalyst for rhodamine B (RhB) contaminated wastewater treatment.

The aim of this work is to investigate the adsorption performance of orange G (OG) dye from aqueous solutions employing PANI@sawdust biocomposite enrobed by calcium-alginate biobeads (Alg-PANI@SD). The as-prepared adsorbent was characterized by scanning-electron-microscopy (SEM), X-ray energy dispersive spectroscopy (EDS) and Fourier transforms infrared (FT-IR) spectroscopy, and used to remove Orange G dye from water. batch tests were performed as a function of adsorbent dosage, pH, contact time, interfering ions and initial OG dye concentration. Experimental results show that the kinetic model of pseudo-first-order (PFO) and Freundlich isotherm provided a good fitting of the whole experimental data. The results revealed that the as-prepared tricomposite Alg-PANI@SD, has the potential to be applied as a low-cost adsorbent for the adsorption of OG dye from aqueous media.

This work aims to investigate the adsorption performance of orange G (OG) dye from aqueous solutions employing PANI@sawdust biocomposite enrobed by calcium-alginate bio-beads (Alg-PANI@SD). The as-prepared adsorbent was characterized by scanning-electron-microscopy (SEM), X-ray energy-dispersive spectroscopy (EDS), and Fourier transforms infrared (FT-IR) spectroscopy and used to remove orange G dye from aqueous water. Batch tests were performed as a function of adsorbent dosage, pH, contact time, interfering ions, and initial OG dye concentration. Experimental results show that the kinetic model of pseudo-first-order (PFO) and Freundlich isotherm perfectly fit the entire experimental data. Additionally, the prepared composite exhibited an excellent regeneration capacity and reusability for OG dye removal. The results revealed that the as-prepared Alg-PANI@SD bio-beads have the potential to be applied as a low-cost adsorbent for the adsorption of OG dye from aqueous media.

The focus of the current research is to evaluate the adsorption mechanisms of sodium salicylate and metronidazole on the polyaniline (PANi) using density functional theory (DFT) at B3LYP/6-31G(d) level of theory. The molecular electrostatic potentials of sodium salicylate, metronidazole and PANi were calculated. The theoretical data show that the oxygenated functional groups of adsorbates and amino groups of PANi are the nucleophilic and electrophilic attack sites, respectively. The structural, electronic and energetic properties of PANi complexed with sodium salicylate and metronidazole were investigated. The adsorption mechanism is due to the formation of hydrogen bond between polymer and adsorbate molecules. The low intermolecular electron transfer at solute/solid interface reveals that the sodium salicylate and metronidazole are physisorbed onto the PANi. In addition, the interaction energies between PANi and adsorbate molecules suggest the stability of the formed complexes, indicating a good adsorbate-adsorbent affinity. All quantum chemical data are in good agreement with the experimental observations.

Herein, a novel PANI@Fe2O3@TiO2 (PANI@TF) composite containing different amounts of polyaniline was synthesized by in situ polymerization of aniline monomer in the presence of TF. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), BET surface area, Diffuse reflectance spectroscopy (DRS), X-ray photoelectron (XPS), and scanning electron microscopy (SEM-EDS) were used to study the phase structure, morphology, and optical properties of the synthesized PANI@TF composites. Moreover, for the first time, the photocatalytic property of the as-synthesized PANI@TF composites has been evaluated via the decolorization of MB under sun-like illumination. The findings confirmed that all the PANI@TF ternary composites with different PANI content showed enhanced visible-light photocatalytic activity for methylene blue (MB) dye degradation compared to pure Fe2O3@TiO2. The highest degradation efficiency for MB via 1% PANI@TF ternary catalyst reached 96% after 2 h under sun-like illumination, which was 4.3 higher than TF. Finally, a plausible photocatalytic mechanism for the improved photocatalytic activity was proposed to guide further improvement of its photocatalytic performance.

Purine and pyrimidine bases (uracil and its homologs thymine and 5-halogenouracile) come from the decomposition of nucleic acids: Uracil is found only in RNA. Thymine is normally found in DNA; sometimes tRNA will contain some thymine as well as uracil. These biomolecules are present in natural waters and had a biological interest principally at the level of cells, whether in the presence or absence of metal cations. In this context, the complex formed by Hg(II) and Cd(II) with uracil bases has been characterized chemically and structurally by the theoretical quantum density functional theory (DFT) method. The metal ion surrounded by the oxygen (O7) and nitrogen (N5) from the uracil-based ring formed tetradentate coordination; solvation effects are taken into consideration by SCRF (solvent cavity reaction field) approach. The objective of this work is to estimate the stability of the complexes formed between uracil-based and metal Hg(II) and Cd(II). This allows the identification of the most stable geometries and calculates the means values characteristic of the different complexes. We can deduce that for the two metal ions, that the complex formed with the hydroxide group, XHg(OH)2 (X = Cd, Hg) is the most stable component.

International audience; Nowadays, the global spreading of hazardous heavy metals becomes a top-priority environmental challenge, owing to its serious detrimental health outcomes. Herein, a novel cysteine-doped polyaniline@faujasite hybrid composite (Cys-PANi@FAU-50) was synthesized via a facile in-situ polymerization route for the effective detoxification of Cr(VI)-bearing wastewaters. The Cys-PANi@FAU-50 composite displayed an open mesoporous structure richly decorated with nitrogen/oxygen-containing functional groups, which consequently boosted the diffusion, adsorption and reduction of Cr(VI) oxyanions. The Cr(VI) adsorption behavior was satisfactorily tailored via pseudo-second-order law and Langmuir model with a maximum uptake capacity of 384.6 mg/g. Based on the advanced statistical physics theory, the monolayer model with two distinct receptor sites provided a reliable microscopic and macroscopic prediction of the Cr(VI) adsorption process. Stereographically, the Cr(VI) ions were adsorbed through horizontal multi-anchorage and vertical multi-molecular mechanisms on the amine and hydroxyl groups of Cys-PANi@FAU-50, respectively. The thermodynamic functions evidenced that the Cr (VI) adsorption was an endothermic spontaneous process. XPS analysis proved that Cr(VI) ions were electrostatically adsorbed, and subsequently reduced to Cr(III), which were in turn immobilized by chelation with imine/sulfonate groups and electrostatic interactions with carboxylate groups. The Cys-PANi@FAU-50 featured an effortless regenerability and good reusability. Overall, the Cys-PANi@FAU-50 composite owns outstanding potentiality for detoxifying Cr(VI)-laden effluents.

The present study describes the preparation of a novel 1,2,4,5-benzene tetracarboxylic acid doped polyaniline@zinc phosphate (BTCA-PANI@ZnP) nanocomposite via a facile two-step procedure. Thereafter, the as-prepared composite material adsorption characteristics for Cr(VI) ions removal were evaluated under batch adsorption. Kinetic approach studies for Cr(VI) removal, clearly demonstrated that the results of the adsorption process followed the pseudo second order and Langmuir models. The thermodynamic study indicated a spontaneous and endothermic process. Furthermore, higher monolayer adsorption was determined to be 933.88 mg g−1. In addition, the capability study regarding Cr(VI) ions adsorption over BTCA-PANI@ZnP nanocomposite clearly revealed that our method is suitable for large scale application. X-ray photoelectron spectroscopy (XPS) analysis confirmed Cr(VI) adsorption on the BTCA-PANI@ZnP surface, followed by its subsequent reduction to Cr(III). Thus, the occurrence of external mass transfer, electrostatic attraction and reduction phenomenon were considered as main mechanistic pathways of Cr(VI) ions removal. The superior adsorption performance of the material, the multi-dimensional characteristics of the surface and the involvement of multiple removal mechanisms clearly demonstrated the potential applicability of the BTCA-PANI@ZnP material as an effective alternative for the removal of Cr(VI) ions from wastewater.

Arginine-doped polyaniline@walnut shell (Arg-PANI@WNS) hybrid composite was prepared through interfacial polymerization reaction of aniline on the walnut shell particles surface in the presence of arginine. The as-synthetized composite characterization was made through energy dispersive X-ray spectroscopy (EDS), field emission scanning electron microscopy (FE-SEM), Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and surface charge analysis. The Arg-PANI@WNS composite was subjected to Cr(VI) adsorption experiments from artificially contaminated solutions. Kinetics and equilibrium results were satisfactorily tailored via pseudo-second-order model and Freundlich isotherm. Optimum monolayer uptake capacities at pH 2 and 303 K were 450.53 and 562.83 mg·g−1 for PANI@WNS (prepared under otherwise identical conditions in the absence of arginine) and Arg-PANI@WNS, respectively. The Cr(VI) species binding mechanism was elucidated by the electrostatic interactions as a pivotal driving force. Desorption results demonstrated the excellent reusability of Arg-PANI@WNS composite during the clean-up of solutions containing Cr(VI) ions. Furthermore, Cr(VI) ions adsorption process was optimized via response surface methodology (RSM). Under optimized conditions, using Arg-PANI@WNS dose of 0.30 g·L−1 and Cr(VI) concentration of 50 mg·L−1 at pH 2 and 303 K, the predicted Cr(VI) ions removal efficiency was found to be 99.8%, which correlates reasonably well with actual values. Thus, the results obtained in the present study clearly revealed that the as-synthesized Arg-PANI@WNS hybrid composite could be taken as a potential filter to effectively clean-up hazardous Cr(VI) ions in industrial effluents.

Synthetic dye waste is one of the world's key ecological concerns. The algal biomass has emerged as a promising alternative adsorbent for wastewater treatment. The present study deals with the functionalization of brown algae (BA) by citric acid in order to improve its adsorption ability for textile dye removal in aqueous solutions. The morphological texture (SEM and BET) and surface chemistry (FTIR, EDS-mapping, and PZC) of the novel functionalized brown algae (designated as BA-CA) were analyzed. The performance of BA-CA for crystal violet (CV) dye removal from wastewater was investigated. The isotherm and kinetic adsorption modeling indicate the good fit of Langmuir isotherm and pseudo-second-order models. Optimum monolayer uptake capacity was 279.14 mg/g for BA-CA, which was about two times higher than that of unmodified BA. The thermodynamic parameters clearly indicated that CV removal process was physiosorption, exothermic, and spontaneous in nature. The regeneration study showed excellent reusability of the BA-CA up to five cycles. Overall, the experimental findings lead us to conclude that the BA-CA can be used as an eco-friendly, cost-effective and easily regenerated adsorbent for the purification of textile effluents.

International audience; A polyaniline@Fe-ZSM-5 composite was synthesized via an in situ interfacial polymerization procedure. The morphology, crystallinity, and structural features of the as-developed PANI@Fe-ZSM-5 composite were assessed using scanning electron microscopy – energy dispersive spectroscopy (SEM-EDS), X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). The composite was efficiently employed for the first time as an adsorbent to adsorb Orange G (OG) dyestuff from water. The OG dye adsorption performance was investigated as a function of several operating conditions. The kinetic study demonstrated that a pseudo-second-order model was appropriate to anticipate the OG adsorption process. The maximum adsorption capacity was found to be 217 mg/g. The adsorption equilibrium data at different temperatures were calculated via advanced statistical physics formalism. The entropy function indicated that the disorder of OG molecules improved at low concentrations and lessened at high concentrations. The free enthalpy and internal energy functions suggested that the OG adsorption was a spontaneous process and physisorption in nature. Regeneration investigation showed that the PANI@Fe-ZSM-5 could be effectively reused up to five cycles. The main results of this work provided a deep insight on the experimental study supported by advanced statistical physics prediction for the adsorption of Orange G dye onto the novel polyaniline@Fe-ZSM-5 hybrid composite. Additionally, the experimental and advanced statistical physics findings stated in this study may arouse research interest in the field of wastewater treatment.

International audience; In the current study, an in-situ oxidative polymerization method was used to synthesize polyaniline-coated tungsten trioxide biphasic composite (PANI@WO3). The as-developed composite material properties were elucidated using different characterization tools such as X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), N2 sorption-desorption isotherm, and X-ray photoelectron spectroscopy (XPS). The PANI@WO3 was further applied to remove hexavalent chromium (Cr(VI)) from aqueous solutions. The results demonstrated that the optimal removal efficacy was achieved at pH 2. Meanwhile, the pseudo-second-order kinetic and isotherm of the Langmuir model were fitted for Cr(VI) adsorption. Cr(VI) amount of 549.37 mg·g−1 was the maximum capacity of adsorption attained for PANI@WO3, which is significantly higher than that of existing adsorbents. From a thermodynamic point of view, the Cr(VI) adsorption process occurred spontaneously and endothermically. Importantly, PANI@WO3 still exhibited an excellent adsorption capability after five regeneration cycles, indicating the potential reusability of the PANI@WO3 composite. XPS analysis of PANI@WO3 surface after adsorption of Cr(VI) confirmed its adsorption and concomitant reduction into Cr(III) ions. The transfer of mass phenomenon, electrostatic attraction, and reduction reaction were the primary processes for Cr(VI) ions elimination. These findings revealed that the synthesized PANI@WO3 exhibited a high potential for wastewater treatment containing Cr(VI).

A polyaniline-modified almond (PANI@AS) and walnut shells (PANI@WS) biocomposites were designed and prepared via the in situ chemical polymerization in this investigation. SEM-EDX, FT-IR, and potentiometric titration were combined to analyze the texture and chemical structure of the as-synthetized PANI@AS and PANI@WS biocomposites. A dynamic adsorption process was employed to test the as-prepared biocomposite adsorbent performance to adsorb Orange G (OG) dye from effluents. The phenomenon of adsorption of OG on the as-prepared biocomposites has been found dependent on various operating conditions. Hence, this finding disclosed the suitable capability employment of PANI@WS and PANI@AS biocomposites for treating wastewater.

The extensive use of persistent antibiotics to prevent human and animal infectious diseases has emerged as a global environmental concern. In this study, we report the effective removal of Ciprofloxacin (Cipro) antibiotic from aqueous solutions using a novel Hydroxyapatite@Montmorillonite (HAP@Mt) hybrid composite, which was synthesized via a facile co-precipitation route. The as-prepared HAP@Mt composite was thoroughly characterized by scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS), transmission electron microscopy (TEM), N2 adsorption-desorption, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric and differential thermal analysis (TGA-DTA). The adsorption performance of HAP@Mt for Cipro antibiotic was investigated as a function of various physicochemical parameters. The Cipro adsorption process on the HAP@Mt composite was well described by pseudo-second-order kinetics and the Langmuir isotherm. The maximum uptake capacity reached 91.18 mg g−1. The Cipro binding mechanism was predominantly controlled by the electrostatic interactions, hydrophobic interactions, hydrogen bonding and n-π electron donor/acceptor interactions. HAP@Mt exhibited easy regeneration and excellent reusability for Cipro removal. Monte Carlo/SA simulations were performed to more clearly illuminate the atomic-level interactions between Cipro molecule and HAP@Mt surface under different pH conditions. The simulation data correlate well with actual results. The obtained experimental and computational findings provide new relevant insights on the application of HAP@Mt composite as a potential binder material to remove Cipro antibiotic from wastewater.

A novel polyaniline@Almond shell (PANI@AS) biocomposite was synthesized via facile in situ chemical polymerization method. The as-synthesized adsorbent was characterized using various analytical techniques such as Fourier transform infrared spectroscopy (FTIR), X-ray energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM), and potentiometric titration. A batch adsorption system was applied with the aim of investigating as-synthesized adsorbent ability to remove Cr(VI) ions and Orange G (OG) textile dye from aqueous solutions. Obtained results revealed that adsorption process was strongly depended upon the physicochemical parameters. The adsorption of Cr(VI) and OG dye onto PANI@AS was better described by the pseudo second-order-kinetic model and followed the Freundlich isotherm model. The maximum uptakes were 335.25 for Cr(VI) and 190.98 mg g−1 for OG dye. We further evaluated that PANI@AS biocomposite could be regenerated easily with NaOH solution and efficiently reused for Cr(VI) and OG dye removal from aqueous media. Thus, these results indicated the potential practical application of PANI@AS biocomposite for wastewater treatment.

In this study, the synthesis of a novel arginine-functionalized polyaniline/FeOOH (Arg-PANI@FeOOH) composite for hazardous Hexavalent chromium ions (Cr(VI)) removal from wastewater was reported. The SEM, EDS, FTIR, XRD, and PZC measurements were used to characterize the as-developed Arg-PANI@FeOOH composite. Batch adsorption experiments were used to investigate the influence of pH, temperature, contact time, Arg-PANI@FeOOH amount, initial Cr(VI) concentration and coexisting ions on the efficiency of Cr(VI) removal. The Cr(VI) adsorption was much more advantageous at lower pH values, reflecting that the electrostatic interactions were the main driving forces that govern Cr(VI) binding mechanism on the Arg-PANI@FeOOH surface. The experimental data showed good fitness to the pseudo-second-order kinetics and Langmuir isotherm. The Cr(VI) species highest monolayer coverage capacity onto Arg-PANI@FeOOH was 682.30 mg g−1. The adsorption of Cr(VI) onto the Arg-PANI@FeOOH is spontaneous via an endothermic reaction. The competing anions were not affected the Cr(VI) adsorption, demonstrating that the Arg-PANI@FeOOH selectively adsorb Cr(VI) ions. The developed Arg-PANI@FeOOH material demonstrated good reusability up to five regeneration cycles. The process capability to predict the practical aptitude of Arg-PANI@FeOOH adsorbent to remove Cr(VI) from aqueous solutions was successfully applied. As a result, the adsorption of Cr(VI) onto Arg-PANI@FeOOH composite is a capable process for full-scale wastewater purification purposes. This paper provides relevant findings for a polyaniline-based adsorbent for the efficient removal of Cr(VI) from wastewater.

BaO-containing glasses of Bi2O–P2O5-V2O5 are synthesized by a conventional melt-quenching method. The as-prepared samples are first heat-treated at 350 °C overnight, and then heat-treated at 1000 °C for 30 min. The as-prepared samples are studied for their physicochemical properties using FTIR, SEM, and EDX analysis. A study of the as-prepared photocatalytic properties for the degradation of common organic dyes such as RhB under UV light is carried out. The highest rate of degradation (70%) is observed when a Bi(0.5-y)BayP(0.75-0.5y)V(0.75-0.5y)O4.5-3y catalyst with y = 0.1 was used. This sample maintains high photocatalytic activity after three cycles, without any significant decrease.

Elevated concentrations of nutrient in wastewater discharge can lead to severe imbalance water-ecosystems due to eutrophication, therefore, efficient and cost-effectiveness remediation strategies are urgently required. This work reports the feasibility of using zirconium-modified Merlinoite (Zr@Merl) obtained from Mexican coal fly ash (CFA) for the removal of phosphate ions from aqueous solutions. Direct method and soft reaction conditions were employed to synthesis Merlinoite (Merl) in more than 100% yield related to CFA. Further, the Merl surface was modified by ZrO2+ through the microwave-assisted process at 130 °C for 5 min. Inductively coupled plasma confirmed the increase of Zr(IV) content up to 7.07 wt% while the potassium concentration decreased from 11.53 to 5.66 wt%, indicating the successful exchange in the Merl surface. The pristine Merl and its Zr@Merl were physicochemically characterized. X-ray photoelectron spectroscopy analysis before and after phosphate ions adsorption was done to elucidate the involved adsorption mechanism. The adsorption behavior was explained by pseudo-second-order and Freundlich models. The maximum adsorbed amount was 67.72 mg g−1. The results proved that the involved mechanisms for the phosphate sorption onto Zr@Merl were electrostatic attractions followed by coordination reactions. Further, a theoretical study using Monte Carlo/SA simulations was applied to get insight into the interaction between Merl and Zr@Merl surface groups and H2PO4− ions. The simulation results demonstrate the favorable adsorption, more stable and spontaneous, onto Zr@Merl than Merl. Overall, Zr@Merl could serve as a cost-effective and reusable adsorbent material for the phosphate recovery from aqueous effluents.

The current study reports the first use of Fe-ZSM-5 as a potential adsorbent for textile effluent purification. The Fe-ZSM-5 zeolite was synthesized through a hydrothermal method using tetrapropylammonium bromide as an organic structure-directing template for application as a binder for basic Fuchsin (BF) dye from aqueous media. SEM observations confirmed that Fe-ZSM-5 exhibits a granular shape with a quasi-hexagonal structure, which is in agreement with its crystallinity demonstrated by XRD analysis. FTIR analysis indicates the abundance of Si OH groups on the Fe-ZSM-5 surface. N2 adsorption-desorption measurement showed the microporous structure (pore size around 1.93 nm) of Fe-ZSM-5 with a BET surface area of 399 m2/g. The uptake performance of Fe-ZSM-5 zeolite for BF dye was systematically studied as a function of different operational parameters. The experimental adsorption data were in good agreement with pseudo-second-order kinetics and Langmuir isotherm with a maximum adsorbed amount of 251.87 mg/g. BF dye adsorption onto Fe-ZSM-5 was a spontaneous and endothermic phenomenon. The binding mechanism is attributed to electrostatic interactions combined with H-bonding. Further, the response surface modeling permits us to optimize BF dye adsorption process. The highest BF dye removal performance was found to be 99.6 % under optimum conditions of pH 5, Fe-ZSM-5 dose 0.75 g/L, initial BF concentration 10 mg/L for 120 min at 20 °C. The findings of this work revealed that Fe-ZSM-5 zeolite could be proposed as an alternative adsorbent with outstanding performance for BF dye removal from wastewaters.

Present study reports the synthesis of the polyaniline-polypyrrole (PPY-PANi) copolymer and its subsequent application for aqueous metronidazole removal under batch adsorption trials. The experiments were then performed to determine the influence of different adsorption parameters such as adsorbent dose, pH, reaction time, initial concentration and temperature on the adsorption process. The obtained experimental data was further evaluated by using different kinetic, isotherm and thermodynamic modeling. The pseudo-first order model provided the satisfactorily explanation for metronidazole kinetic adsorption over PPY-PANi adsorbent. The equilibrium experimental data was in good agreement with Freundlich model. The thermodynamic parameters reveal that the adsorption was spontaneous and exothermic in nature. Metronidazole adsorption mechanism over PPY-PANi surface sites was further evaluated by employing density functional theory (DFT) method. The calculated data indicated that the metronidazole adsorption was mainly accomplished via nucleophilic groups (containing oxygen atoms) of metronidazole over the electrophilic attack sites (-NH-) of PPY-PANi adsorbent. The interaction energy bond clearly suggests that the adsorption of metronidazole over PPY-PANi is a physisorption in nature. Thus, based on these above-mentioned experimental results and DFT data, we concluded that PPY-PANi copolymer could be taken as an alternative filter material for pharmaceutical contaminated wastewater treatment.

Semiconductor photocatalysis is regarded as most privileged solution for energy conversion and environmental application. Recently, photocatalysis methods using bismuth-based photocatalysts, such as BiPO4, have been extensively investigated owing to their superior efficacy regarding organic pollutant degradation and their further mineralization into CO2 and H2O. It is well known that BiPO4 monoclinic phase exhibited better photocatalytic performance compared to Degussa (Evonik) P25 TiO2 in term of ultraviolet light driven organic pollutants degradation. However, its wide band gap, poor adsorptive performance and large size make BiPO4 less active under visible light irradiation. However, extensive research works have been conducted in the past with the aim of improving visible light driven BiPO4 activity by constructing a series of heterostructures, mainly coupled with π-conjugated architecture (e.g., conductive polymer, dye sensitization and carbonaceous materials). However, a critical review of modified BiPO4 systems using π-conjugated materials has not been published to date. Therefore, this current review article was designed with the aim of presenting a brief current state-of-the-art towards synthesis methods of BiPO4 in the first section, with an especial focuses onto its crystal-microstructure, optical and photocatalytic properties. Moreover, the most relevant strategies that have been employed to improve its photocatalytic activities are then addressed as the main part of this review. Finally, the last section presents ongoing challenges and perspectives for modified BiPO4 systems using π–conjugated materials.

A new approach is adopted in this study to eliminate orthophosphates in the aqueous medium. It is about synthesizing a composite from a conductive polymer (Polyaniline) and a sandy material (Hematite-titaniferous sand). The synthesized composite (PANI@HTS) and its components were characterized with (XRD) X-ray diffraction, (XRF) X-ray fluorescence, (SEM) scanning electron microscopy coupled with (EDS) energy dispersive X-ray spectroscopy, (FTIR) Fourier-transform infrared spectroscopy and laser diffraction particle size analysis. The phenomenon of adsorption of orthophosphates on PANI@HTS has found to be dependent on several factors, such as adsorbent dose, pH, contact time and pollutant concentration. From the study of adsorption kinetics and the effect of pollutant concentration, the Langmuir model and the pseudo second order model were the most suited for explaining adsorption phenomena with a highest correlation (R2 > 0.98). The adsorbed amount that was found in this study reaches 16.15 mg/g. The adsorption mechanism of orthophosphate ions onto PANI@HTS composite was computationally investigated using Density Functional Theory (DFT). The adsorbate-adsorbent interfacial interactions are assumed to be physisorption in nature due to the low values of binding energy and electronic charge transfer. This DFT simulation result is in good adequacy with the experiment. The capability study of the present process has shown that our method is capable, satisfactory and can be applied on a large scale.