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In the study, the layered double hydroxide (LDH) of NiZnFe and its composites with date-palm biochar (LDH-DPb) and carbon nanotubes (LDH-cnt) were synthesized for adsorbing reactive black 5 (RB5) dye from aqueous solutions. In the first 5 min, rapid adsorption was followed by a gradual increase in both dye uptake and removal efficiency of up to 60 min of starting time. In the investigated pH range (3.0–8.0), the removal efficiency linearly decreased while the sorption capacity linearly increased for all three adsorbents as their doses increased to 0.3 or 0.4 g following a decreasing trend up to 0.6 g. By increasing the initial RB5 concentration from 10 to 100 mg L−1, the removal efficiency linearly decreased. A nearly perfect fitting of the pseudo-second-order kinetic model to the adsorption data was observed; however, the Elovich kinetic model showed the heterogeneous surface of adsorbents with chemisorption. At the solid–liquid interface, from a thermodynamics point of view, we obtained the nonspontaneous nature of the adsorption of RB5 dye of the studied adsorbents with an increased disorder, which supported the endothermic nature onto the studied adsorption process. Furthermore, a nearly perfect fitting of the Langmuir model was obtained to the adsorption data, thereby suggesting the monolayer adsorption of RB5 dye onto the studied adsorbents. In the Dubinin–Radushkevich model, a good agreement of the calculated adsorption capacities to the experimental values were observed and the chemical adsorption of RB5 dye on to the studied adsorbents was proposed based on E (8 – 16 kJ mol−1).

An innovative application of the solvent evaporation technique was suggested. Solvent evaporation technique is a technique for drug encapsulation and nanosphere preparation. Th widely used technique is also facing the problem of low actual drug entrapment percent, which is not economic from the industrial view. The goal of this work is trying to use the advantage of this technique concerning the product sphericity and the ability to control particle size, to prepare a drug as pure crystals spheres. Ibuprofen is selected as a model drug. The spheres are formed by using Polyvinyl pyrrolidone (PVP) or Polyethylene glycol (PEG) as an antiaggregating agent but not formed on using tween or span. Particle size and actual drug content depend on the concentrations the antiaggregating agent used. Surfaces of the drug crystal spheres are porous with empty sphere internal structure on using PVP but spongy and rough on using PEG. The drug has its identity chemical form in the drug crystal spheres. IR scan of spheres prepared on using PEG showed a characteristic ether peak. DSC showed melting endothermic peak of PEG, but X-ray showed minor change in the drug crystal patterns. Drug release profiles from crystal spheres prepared with the same antiaggregating agent are close to each other. The drug release profiles from drug crystal spheres prepared by using PEG are more controlled than that prepared by using PVP. The drug release mechanism is diffusion. It was concluded that, the same technique could be suggested for preparation of other biomedical material in pure crystals spheres with controlled particle size. These properties may encourage to prepare very small particles with spherical shape for inhalation or injection as an innovative particle technology application for the widely used technique.

A redox process combining propane dehydrogenation (PDH) with selective hydrogen combustion (SHC) is proposed, modeled, simulated, and optimized. In this process, PDH and SHC catalysts are physically mixed in a fixed-bed reactor, so that the two reactions proceed simultaneously. The redox process can be up to 177.0% higher in propylene yield than the conventional process where only PDH catalysts are packed in the reactor. The reason is twofold: firstly, SHC reaction consumes hydrogen and then shifts PDH reaction equilibrium towards propylene; secondly, SHC reaction provides much heat to drive the highly endothermic PDH reaction. Considering propylene yield, operating time, and other factors, the preferable operating conditions for the redox process are a feed temperature of 973 K, a feed pressure of 1 bar, and a mole ratio of H2 to C3H8 of 0.15, and the optimal mass fraction of PDH catalyst is 0.5. This work should provide some useful guidance for the development of redox processes for propane dehydrogenation.

Along this research the (110), (101) (200) and (211) surfaces were chosen to be studied by considering their atomic surface density. The surfaces were studied using CASTEP for the transition state search by DFT calculations, the initial coordinates that establish the SnO2-Methane distance were obtained with Adsorption Locator, a software able to calculate adsorption configurations using Monte Carlo methods. The results show that in terms of overall energy change, surface (101) presents the most favorable configuration with an exothermic total-energy change (form CH4 on the surface to a CO and H2O molecules on the surface) of − 18.47 kcal/mol, being the worst case the CH4 on a (200) surface with an endothermic total energy-change of 128.86 kcal/mol. In terms of the TS energy, the (101) surface remains as the most favorable system with energy maximums on the TS reaction path of 99.25 kcal/mol for the dissociation and adsorption of the CH4 molecule on the surface, and a maximum of 266.42 kcal/mol for the desorption and formation of the CH4 and H2O molecules on the SnO2 surface.

The equilibrium solubility of 2,4-diaminobenzenesulfonic acid and super solubility as well as metastable zone width were measured in (H2SO4+ H2O) system by the laser dynamic method at elevate temperature range from 298.15 K to 338.15 K. 2,4-diaminobenzenesulfonic acid solubility dependence on the temperature and solvent composition were correlated by the modified Apelblat equation, (CNIBS)/Redlich-Kister model and Jouyban-Acree model. The correlated results by three correlation models were in good accord with the experimental values according to relative average deviations (RD), root-mean-square deviations (RMSD), and correlation coefficients (R2). The metastable zone width increased with temperature and sulfuric acid content. The dissolution enthalpy, dissolution entropy and the Gibbs energy were calculated from the experimental values, which indicated that dissolution process of the 2,4-diaminobenzenesulfonic acid was endothermic. The solubility and calculation models of 2,4-diaminobenzenesulfonic acid in (sulfuric acid +water) system could provide the basic data to the crystallization and purifying of the 2,4-diaminobenzenesulfonic acid.

Pd40Ni40P20 (at.%) samples with different enthalpy states were fabricated through high-pressure torsion or sub-Tg annealing of the as-cast material. Subsequently, the underlying structural relaxation was studied by in-situ shear modulus measurements and modulated differential scanning calorimetry. The results show that high-pressure torsion leads to shear modulus softening and an increase of the nonreversible exothermic enthalpy, indicating a significant structural rejuvenation, while sub-Tg annealing causes shear modulus hardening and a decrease of the nonreversible exothermic enthalpy. The reversible endothermic effect which can reflect the fractional change of supercooled liquid with temperature was found to be almost identical for all samples, and independent of deformation or thermal history. The total heat flow can be well correlated with the shear modulus within the framework of interstitialcy theory. Furthermore, we demonstrate that the structural relaxation below Tg decouples into internal stress relaxation and β-relaxation. In addition, this work indicates that the processes of α-relaxation and β-relaxation in the metallic glass are of similar structural origin but occur on different spatial scales.

This study developed a method to fabricate a surface-oxidized rigid carbon foam (ORCF) with hierarchical macro-nanoporous structure via KOH activation of the carbon foam with two kinds of macropores followed by HNO3 hydrothermal oxidation. The structures of the prepared ORCF were characterized using scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared (FTIR) spectra, X-ray photoelectron spectroscopy, and N2 adsorption-desorption analyzer. Results demonstrate that the ORCF possesses a fluffy and porous structure with rich oxygen-containing groups. There are numerous through-holes on its pore surfaces connected with two-level macropores forming hierarchical macroporous channels. Meanwhile, the ORCF remains a good bulk structure with a compression strength of 0.74 MPa at a bulk density of 0.09 g cm−3. Batch adsorption experiments for malachite green (MG) and Pb2+ were studied through the single variable method to investigate the effects of different initial conditions on its adsorption process. The ORCF has maximum adsorption capacities for MG and Pb2+ of 587.68 mg g−1 and 157.80 mg g−1 with high partition coefficients of 17.41 mg g−1 µM−1 and 14.86 mg g−1 µM−1, respectively. The experimental data are suitable for Langmuir isotherm and Pseudo-second-order kinetic models, which correspond to monolayer chemisorption. Thermodynamic analysis indicates that the adsorption process is spontaneous and endothermic. Moreover, the removal percentages of MG and Pb2+ by the ORCF could remain above 90% after five cycles, implying that the ORCF is an efficient adsorbent with good adsorption ability and cycling stability.

Textile wastewater contains highly toxic, nondegradable, carcinogenic organic pollutants, causing severe damage to the ecological environment. In this work, β-cyclodextrin carbon-sphere-based nanocomposite (CS/SiO2@β-CD) with a core–shell–shell configuration was prepared by hydrothermal synthesis and subsequent sedimentation-azeotropic distillation with SiO2 as intermediate layer for the removal of crystal violet (CV) and bisphenol A (BPA). The chemical structure and morphology of the CS/SiO2@β-CD were characterized by FT-IR, SEM and TEM. The effects of contact time, pH, temperature and initial concentration of the absorbates on the adsorption property were explored. The CS/SiO2@β-CD showed excellent adsorption capacity on CV and BPA, and the maximum adsorption capacity was 87.873 mg g–1 and 165.095 mg g–1, respectively. Their adsorption process was in line with the pseudo-second-order and pseudo-first-order kinetic models, respectively. The adsorption thermodynamics could be better fitted by Langmuir model than by Freundlich model. The calculated thermodynamic parameters (–ΔG0, ΔS0 and ΔH0) illustrated the adsorption of CV was endothermic, in contrast, the adsorption of BPA was exothermic process. Furthermore, the CS/SiO2@β-CD showed excellent recovery performance, making it a potential adsorbent for the practical treatment of textile wastewater.

Zeolitic Imidazolate Frameworks (ZIFs) represents a subclass of the metal-organic frameworks (MOFs), composed mainly of tetrahedrally coordinated transition metals. The aim of this review was to evaluate the experimental findings on the adsorption of different aqueous pollutants using ZIFs. ZIF adsorption mechanism was electrostatic attraction, π-π interaction and complexation though others were observed based on pollutant type and nature of the solution chemistry. Thermodynamic modelling revealed that ZIF adsorption is usually spontaneous and endothermic. The adsorbent can be re-used for 3–4 cycles with >70% retention of uptake performance. NaOH, methanol and ethanol were observed to be the more suitable and effective eluents for desorption of adsorbate from ZIF. The nature of the adsorbate and the type of uptake mechanism are the two key considerations in competitive adsorption systems. When the uptake mechanism of the main adsorbate species is different from that of the competing species, then the adsorption process is unaffected. Investigations on adsorbent disposal, targeted modification, functionalisation, emerging contaminants removal, column adsorption studies and molecular modelling would be needed to fill in gaps in knowledge in ZIF related studies.

Present work based on thermogravimetric analysis (TGA) to decipher in detail the pyrolysis of mustard stalk (MS) for investigating its potential for bioenergy feedstock at three heating rates (5, 10, and 20 °C/min). The thermal degradation behaviors of MS were carried out at three heating rates (5, 10, and 20 °C/min). The kinetic and thermodynamic parameters were examined using model-free isoconversional Flynn- Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS) model. The obtained activation energy for pyrolysis of MS using FWO and KAS to be 132.47 and 130.62 kJ/mol. Kissinger method was used to compute pre-exponential factor found to be in the range of 105 to 1016 s−1 at different heating rates. The average Δ H was 127.70, and 125.8 kJ/mol and Δ G is 127.74 and 127.87 kJ/mol from FWO and KAS respectively, all Δ H positive indicated endothermic nature. The Coats-Redfern approach was used to estimate the thermal degradation reaction mechanism, which revealed that the diffusion model was best suited to reflect the degradation process involving both exothermic and endothermic reactions. The analysis can help augment the experimental studies, and physicochemical characterization revealed its fuel characteristic since MS is sustainable and promising biomass for alternative processes in terms of waste management strategies.

A study of corrosion inhibition of mild steel by Rhoeo discolors plant extract in 0.5 M HCl solution was carried out by potentiodynamic polarization and electrochemical impedance methods. The different concentration of inhibitor was used ranging between 0.2 g/L−2 g/L in the electrolyte. To determine the efficiency and rate of corrosion at different temperatures say 308 K, 313 K, 318 K. A consequence drop in the rate of corrosion is observed when a higher the concentration of plant extract was used at a higher temperature. It is also observed that a rate of corrosion was increased on concentration of inhibitor with rising in temperature. The use of 2.0 g/L plant extract in the potentiodynamic study shows inhibition efficiency 87.72% (308 K), 79.78% (313 K) and 74.84% (318 K). For electrochemical impedance shows 82.23% (308 K), 79.22%(313 K), 71.20% (318 K).The graph plotted by using log I on x-axis P on y-axis indicates inhibitor controls both anodic and cathodic reactions. It is also observed the value of Ea for inhibited solution ranging from 16.8 kJ/mol to 72.95 kJ/mol, these results interpret physical adsorption of inhibitor over the metal surface leading to the formation of adsorbate film of electrostatic character The positive values of entropy ranging from 26.93 kJ/mol to 73.01 kJ/mol indicates the endothermic nature of physical adsorption and disordering of adsorbent film over the metal surface. At finally it obeys the Langmuir adsorption isotherm.

This paper aims to synthesis a recyclable adsorbent from solid waste using a clean and environmentally friendly method to deal with Cr(VI) water pollution. Magnetic zeolite/chitosan composites (ZFA/MCS) were prepared by the neutralization method. The adsorption properties of ZFA/MCS, prepared by the neutralization method for Cr(VI) ions under different conditions especially cross-linking, were investigated in detail. The results showed that cross-linked ZFA/MCS generally showed higher adsorption capacity than uncross-linked ones. The uncross-linked ZFA/MCS and cross-linked ZFA/MCS showed a saturated adsorption capacity of 25.67 mg·g−1 and 28.47 mg·g−1 at pH = 3 and 30 °C, respectively. The experimental values were followed Langmuir adsorption equations and pseudo-second-order kinetic model, indicating that the adsorption was probably monolayer coverage and chemical adsorption, respectively. The effect of temperature proved that the adsorption was spontaneous and endothermic. Therefore, the adsorbent with excellent recyclability and adsorbability was successfully fabricated via a green synthetic strategy.

Present communication reports on the synthesis, characterization and application of Fe3O4-chitosan composite (MCC). The magnetic chitosan composite are crafted by mixing Fe3O4 nanoparticles solution to chitosan solution. Fe3O4 nanoparticles have been synthesized by co-precipitation method. The synthesized composite have been extensively characterized using various techniques such as FTIR, TEM, XRD and BET analysis. The surface area analysis suggested that the materials synthesized is mesoporous in nature. Incorporation of chitosan crosslinked actively with Fe3O4 nanoparticles that results in reduction of surface area and narrower pore size distribution of the composite than pure Fe3O4 nanoparticles. TEM study demonstrated that Fe3O4 nanoparticles were found in the range of 20–25 nm. The synthesized composite is able to capture more than 89% Cd(II) from synthetic Cd(II) solution within 80 min of contact time. The adsorption equilibrium data better conformed with the Langmuir isotherm. The maximum capacity determined from Langmuir isotherm was 149.92 mg/g at 323 K. Adsorption kinetics of cadmium on MCC could be well analyzed with pseudo-second-order kinetic model. Thermodynamics investigation reveals that with the increase of solution temperature 303 K, 313 K and 323 K the ΔGo values decreases correspondingly to −87.76, −90.36 and -93.36 KJ/mol, suggesting endothermic nature of the adsorption process. The adsorbent could be successfully reused for more than five cycles. Thus, MCC can be serves as a reliable and sustainable material for efficient sequestration of Cd(II) species from aqueous environment.

A novel polystyrene-poly(hydroxamic acid) interpenetrating network resin (PS-PHA IPNs) was successfully synthesized by suspension polymerization and interpenetrating network technology. The effects of various experimental parameters, including pH, contact time and initial concentrations of rare earth ions on the adsorption capacity were discussed in detail. Under the condition of pH 4.0 (La3+), 1.0 (Ce3+) and 3.0 (Y3+), respectively, PS-PHA IPNs can reach equilibrium adsorption in 6 h and get maximum adsorption capacities (1.08, 1.43 and 1.36 mmol/g). The adsorption process of PS-PHA IPNs for La(III), Ce(III) and Y(III) ions can be described by liquid membrane diffusion, particle diffusion and chemical reaction. The adsorption process is a spontaneous and endothermic process and can be better simulated by Langmuir adsorption isotherm. The studies of SEM-EDS indicate that rare earth ions are adsorbed on the surface of PS-PHA IPNs. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis further prove that rare earth ions are chemisorbed on the surface of PS-PHA IPNs. These results reveal that the as-prepared PS-PHA IPNs is a promising adsorbent for adsorption of rare earth ions due to their higher adsorption capacity than other adsorbents.

High-entropy ceramic powders (Mg0.2Co0.2Ni0.2Zn0.2Cu0.2)O were prepared by precipitation. The microstructure and phase composition of the powders were studied by scanning electron microscopy (SEM) and X-ray diffraction (XRD), and the kinetics of thermal decomposition were researched by thermogravimetry and differential scanning calorimetry (TG-DSC). The Popescu integral and Kissinger differential methods were utilized to analyse the TG-DSC results. The XRD results showed that the obtained (Mg0.2Co0.2Ni0.2Zn0.2Cu0.2)O powders were in a pure phase without impurity peaks, and the DSC curve for the calcination process had five endothermic peaks, three of which correspond to the phase transformation process, and their average activation energies were 85.943, 155.333 and 136.374 kJ/mol.

The present work is the first detailed description of the endothermic catalytic reaction of methylcyclohexane (MCH) over H-ZSM-5 zeolites (HZ) and activated charcoals (AC) coated in a multichannel micro-reactor module with novel ultra-compact wavy structure (MR) under supercritical conditions (550 °C, 5 MPa). The MR has an ultra-compact structure with nine micro-channels in parallel that exhibit a size of 120 × 30 mm and a total cross-sectional area of 36 cm2. The catalytic performance of the conventional tube reactor (TR) packed with HZ and AC catalysts was also studied for comparative purposes. All catalysts and reactors were characterized using various techniques such as field emission scanning electron microscope (FE-SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), ammonia temperature-programmed desorption (NH3-TPD). In general, MRs showed always a significantly enhanced MCH conversion (%) performance and heat sink compared with conventional TRs. AC-coated MR showed the highest MCH conversion (%) performance compared to the other reactors. MCH conversion (%) was higher in the following order AC-coated MR (78.70%) > AC-packed TR (70.49%) > HZ-coated MR (68.87%) > HZ-packed TR (54.81%). The AC-coated MR can be one of the candidates for a heat-absorbing reaction for aircraft cooling system control.

In cooling microchannels of advanced flight engines, the fuel temperature rapidly increases to facilitate endothermic cracking reactions. A cooling channel can be divided into noncracking and crack...

The use of primary alcohols (such as methanol) in the production of hydrogen (H2) has been spotlighted as one of the indispensable measures to pursue a greener economy. Here, we address some potential shortcomings concerning the production of H2 based on aqueous methanol electrolysis in reference to steam methane reforming (SMR) as a mature commercial technology. After all, is SMR an economic and low-energy route for H2 production? Is it feasible to use methanol to electrolytically generate H2? The liquid-phase methanol-based hydrogen evolution reaction (HER) at 335 K is an example of a potentially entropy driven reaction (exoergic, even though very endothermic) with a suitable catalyst using either ambient or waste heat. Further, would it be more efficient to use methane as a source of hydrogen via SMR or consume it directly as energy? The suitability of HER is assessed in the context of industrial energy analysis, thermodynamics, and sustainability.

Design and facile fabrication of a magnetically separable hetero-structure photocatalyst as well as an adsorbent having dual green benefits towards energy conversion and pollutant remediation are quite indispensable in the current scenario. In this regard, a composite of citrate capped Fe3O4 and UiO-66-NH2 has been designed to remediate Cr (VI) by adsorption and harvest photons from visible light for clean energy (H2) conversion. The material was prepared by the union of citrate capped Fe3O4 (CCM) and versatile aqueous stable Zr-based MOF (UiO-66-NH2) through in-situ solvothermal method. The composite of CCM with MOF (MU-2) was studied through sophisticated analysis techniques; PXRD, FT-IR, BET, UV–Visible DRS, PL, TG, HRTEM and XPS etc. to reveal the inherent characteristics of the material. BET surface analysis revealed high specific surface area (572.13 m2 g−1) of MU-2 in comparison to its pristine MOF. Furthermore, the dual function composite MU-2′s VSM studies showed that its magnetic saturation is 3.07 emu g−1 that is suitable for magnetic separation after desired reaction from aqueous media. The Cr (VI) sorption studies revealed that the composite adsorbent (MU-2) showed maximum monolayer adsorption capacity (Qm) of 743 mg g−1 which followed pseudo second order kinetics. Moreover, the sorption thermodynamics revealed that the process was spontaneous and endothermic in nature. In addition to it, the synthesized composite material displayed enhanced activity towards photocatalytic H2 evolution with a maximum evolution rate of 417 µmole h−1 with an apparent conversion efficiency (ACE) of 3.12 %. Typically, MU-2 displays high adsorptions of Cr (VI) as well as some extent of Cr (VI) reduction owning to its populous active sites and free carboxylate groups respectively. Moreover, the synergistic effect of CCM and UNH in the composite resulted in Z scheme mediated charge transfer mechanism that showed enhanced H2 photo-evolution rates. Hence, MU-2 can be readily utilized as magnetically retrievable dual function composite for Cr (VI) adsorption and photocatalytic H2 evolution.

The use of heterogeneous catalysts in the transesterification reaction is an eco-friendly and cost-effective approach for biodiesel production as compared to the homogeneous catalyst-based processes. In this study, a heterogeneous cobalt doping Zn/Al complex oxide was prepared by a simple birch-templating method, and successfully applied to the transesterification of jatropha oil with methanol. The catalyst had strong diffraction peaks of ZnAl2O4 spinel crystal with substitutional doping of amorphous cobalt atom. It had a tendency to achieve a high base strength whilst increasing the specific surface area in the presence of cobalt. By contrast to the impregnation and coprecipitation methods, the crystalline particles from templating method were uniformly distributed on the catalyst surface, thus forming a well-defined tiled network with large amounts of grain-free pores. The exposure of available activity sites resulted in a biodiesel yield of 91.4%. After used several times and recycled, the regenerated catalyst also exhibited good catalytic potency without obvious deactivation. The transesterification kinetics satisfied the Pseudo first order model that controlled by the reaction temperature and catalyst dosage. The thermodynamic parameters of ΔH of 16.7 kJ/mol, ΔS of −284.6 J/mol/K, and ΔG of 140.0 kJ/mol suggested an endothermic, endergonic, and non-spontaneous nature of the reaction.

Cobalt (Co) is a potential candidate in replacing copper for interconnects and has been applied in the trenches in semiconductor industry over twenty years. A non-oxidizing reactant is required in plasma-enhanced atomic layer deposition (PE-ALD) of thin films of metals to avoid O-contamination. PE-ALD of Co has been demonstrated experimentally with plasma sources of NH3 or a mixture of N2 and H2, but the growth mechanism and key reactions are not clear. In this paper, we have investigated the reactions of plasma generated radicals H, N, NH and NH2 at metal precursor (CoCp2) terminated Co (001) and (100) surfaces using static DFT calculations at 0 K and molecular dynamics simulations at 600 K. N radicals play an important role in eliminating surface-bound Cp ligand (if any) via pyridine (C5H5N) formation and desorption, whereas H radicals have endothermic reactions for eliminating Cp ligand via CpH formation and desorption. The surface NHx species are eliminated by H radicals via NH3 formation and desorption. The simulations of these key reactions show that on Co(001) surface, the remaining Cp ligand and surface NHx species after the metal precursor pulse will be completely removed with N and H radicals, resulting in Co atoms deposited on Co(001) surface at a coverage of 3.03Co/nm2. Whereas, on Co(100) surface, the surface NH2 species cannot be completely removed via NH3 formation and desorption due to overall endothermic reactions. Instead, H radicals react with trench N species, contributed to H transfer at metal precursor pulse, to form NH. These trench N species cannot be eliminated completely on Co(100) surface, which will be the source of N impurities for the deposited Co thin films. At the post-plasma stage, the metal surface will be covered with NHx-terminations with plasma generated NH radicals, which is then ready for the next deposition cycle. Our results explain why ammonia or H2/N2 plasma, which produce NHx species are required to deposit Co thin films using Co metallocene precursors.

In the present work, nano-composite of CoFe2O4-MnO2 has been successfully synthesized by a simple wet chemical route in three steps. Samples were sintered at 800 °C for a period of 5 hrs to get the desired phases. X-ray diffraction studies have confirmed the existence of both CoFe2O4 and MnO2 phases. The average crystallite size was found to be 59.8 nm. Fourier Transform Infrared Spectroscopy analyses confirmed the occurrence of both phases by showing a characteristic band of ferrites at octahedral and tetrahedral sites as well as the vibrational mode of Mn-O. Scanning Electron Microscope analysis was carried out to study the morphology of the sample, which revealed the rod-like appearance of the composites in nano-scale. The thermal behaviour of CoFe2O4-MnO2 was investigated by using the combined Thermogravimetry-Differential Scanning Calorimetry technique, which revealed the endothermic behaviour of the composite. Characterization of magnetic properties was accomplished by vibrating the sample magnetometer. Saturation magnetization, coercivity, retentivity, and squareness were calculated from the hysteresis loop (M−H Curve) obtained from vibrating sample magnetometer.

In this work, a simple but effective method based on Gamma-ray initiated polymerization was reported for the first time through direct irradiation of CNCs and ionic liquid monomer to obtain poly (ionic liquids) functionalized CNCs (IL@CNCs). The adsorptive removal of Congo red (CR) from aqueous solution by IL@CNCs was also examined and the influence of contact time, pH values, initial concentrations and temperature on adsorption behavior was investigated in detail. Under the same adsorption conditions, the adsorption capacity was increased from 59.72 mg/g (CNCs) to 195.83 mg/g (IL@CNCs). The results of the adsorption isotherm and adsorption kinetics showed that the experimental data were more suitable to be described by the Freundlich isotherm adsorption model and the pseudo-second-order model. The adsorption process of CR on the surface of the adsorbent was endothermic and spontaneous. When the aqueous solution was acidic, it was more conducive to the adsorption of CR. At 100% breakthrough, the value of adsorption capacity is 199.95 mg/g and the value of partition coefficient is 9.64. Moreover, the adsorption capacity is expected to be further improved through adjustment of polymerization parameters and this method can also be used for preparation other poly (ionic liquids) modified composites.

Toxic heavy metal ions, valuable noble metal ions and organic dyes are significant concerns in wastewater treatment. In this work, MoO3 nanobelts (MoO3 NBs) prepared by solvothermal method and MoS2 nanoarrays (MoS2 NAs) constructed using MoO3 NBs precursor were proposed to effectively remove heavy/noble metal ions and organic dyes, such as Pb(II), Au(III) and Methylene Blue (MB). The two adsorbents exhibited the excellent adsorption capacity towards Pb(II), Au(III) and MB. The maximum removal capacity of Pb(II) and MB on MoO3 NBs was 684.93 mg/g and 1408 mg/g, respectively, whereas that of Au(III) and MB on MoS2 NAs was 1280.2 mg/g and 768 mg/g, respectively. Furthermore, the thermodynamic parameters were calculated from the temperature-dependent curves, suggesting that the removal of Pb(II) and Au(III) on both adsorbents was spontaneous and endothermic. The new adsorbents introduced here were high adsorption activity, ease of fabrication, high scalability, good chemical stability, great repeatability and abundant and cheap supply, which were highly attractive for wastewater treatment.

Bisphenol-A (BPA) is a common plasticizer that has been considered a chemical of concern due to its endocrine disruption potential. In this sense, this paper aimed to investigate the adsorption of this contaminant onto commercial organophilic clay named Spectrogel® as means of water remediation. For this, characterization techniques were carried out before and post-process to identify any major alterations to the adsorbent due to BPA uptake. A statistical central composite rotational design (CCRD) technique was performed for process optimization. The impact of adsorbent dosage mass (0.128–1.472 g.100 mL−1, solution concentration (0.064–0.736 mmol/L−1) and particle diameter (0.28–1.0 μm) on the adsorption capacity was analysed. It was defined 0.064 g of adsorbent dosage and an average particle size of 0.855 μm as optimum conditions, in which a 0.193 mmol.g−1 (44.060 mg.g−1) adsorption capacity was obtained. Static adsorption assays showed that the kinetics better followed the external mass transfer resistance model, whilst the isotherm data obtained at 15 and 25 °C were well expressed by the Freundlich model and at 40 and 55 °C by the D-R model, achieving a maximum adsorptive capacity of 0.4 mmol.g−1 (91.316 mg.g−1). The thermodynamic parameters reflected a spontaneous and endothermic process. Furthermore, numerous eluent solutions were tested to assess the regenerability of the adsorbent and sodium hydroxide displayed the best desorption capacity (77.8%). The Spectrogel® clay has shown to be very promising as an alternative adsorbent in the remediation of water contaminated with BPA.

The current global concern related to ground water contamination especially fluoride (F- contamination has ascended in an increased exigence for effective adsorbents. In this study, we have used a surface altered pectin biopolymer with silica–gel (SG), and incorporation of cerium oxide (Ce@SG-Pec) for the application of F- adsorption studies from the aqueous systems. The temperature, contact time, absorbent dosage, pH, coexisting anions, and initial F- concentration are discussed. The isothermal and kinetic data were fitted to Temkin and pseudo-second-order model, respectively. Analysis of adsorptive thermodynamics showed that the adsorption process was endothermic, spontaneous, feasible, and chemisorption type of adsorption mechanism. The good adsorption is attributed to chemical adsorption through strong surface complexation of cerium and silicon with F- as well as the special structure of adsorbent. The surface analyses (BET and FESEM) had shown the decrease in pore size after the F- adsorption. Additionally, FTIR analyses supported the substantial role of ion–exchange and electrostatic interaction in the adsorption mechanism.

Water pollution with copper (Cu) has a significant impact on the environment and human health. Within this context, the present study aims to synthesize a composite bead based on Moroccan natural clay from Chaouia (CH) and sodium alginate (Na-AL) as adsorbents to remove copper ions from aqueous solution. The adsorbents were characterized using X-Ray Diffraction (XRD), Scanning Electron Microscopy coupled with Energy Dispersive X-ray (SEM-EDX) and Thermogravimetric Analysis (TGA). The effect of adsorbent dose, kinetic time, initial concentration of copper ions and temperature were investigated. Nonlinear regression was applied to fit the isothermal and kinetic models. The results showed that the clay is composed of kaolinite and quartz and the SEM confirmed the successful incorporation of sodium alginate into the clay. The adsorption process follows the Langmuir isotherm with a maximum adsorption capacity of 48.24 and 92.44 mg.g−1 for the clay (CH) and the beads composite designated as (CH@AL), respectively. Pseudo-second-order model best described the kinetic data. Moreover, the thermodynamics of the adsorption was spontaneous and endothermic. All of these results proved that the used adsorbents are eco-friendly and efficient for the adsorption of Cu(II) ions.

To preserve the environment for civilization, we should remove the pollutants like toxic dyes by friendly and cost efficacious method. In this study, the effect of surfactants or mixed surfactants on physicochemical, optical and adsorption properties of ternary mixed oxide CeO2-ZrO2-Al2O3 (CZA) are investigated. The ternary mixed oxide CZA was prepared by surfactants or mixed surfactants assisted ultrasonic co-precipitation method. The physicochemical and optical properties are estimated by different techniques like XRD, TEM, EDX, FTIR, SBET and UV–Vis/DR. The CZAT and CZAC have hybrid shapes and high surface area. The adsorption properties of ternary mixed oxides adsorbents were characterized by sono - removing anionic dyes such as CR and RR. The different factors like contact time, different dye concentrations and temperatures also studied. The kinetics and isotherms applications showed that, the adsorption process was followed pseudo second order kinetics and the Freundlich isotherm model. Also, the adsorption is spontaneous and endothermic process through the thermodynamic study. Finally, the results showed that the ternary mixed oxide nano-adsorbent (CeO2-ZrO2-Al2O3) is promising and functional materials for anionic dye sweep from wastewater.

Milk dust is a prominent remnant of the milk powder packaging industry. The present study reports the thermal degradation pattern and pyrolytic kinetics of milk dust powder (MDP). Thermogravimetric studies were conducted at multiple heating rates (10, 20, 30, and 40 °C min−1) and the obtained biochars were characterized by FTIR, SEM, and XRD. Kinetic analysis was performed using model-free and model-fitting methods. The activation energy obtained by Starink and Friedman methods were 228.29 and 232.46 kJ mol−1, respectively. The frequency factor was found to be in the range between 2.69 × 1010 and 4.37 × 1032 s−1 as determined using the Kissinger method. The MDP pyrolysis followed diffusion (α = 0.05 to 0.2) ensued by higher-order (α = 0.6 to 0.95) reaction mechanism as predicted by the master plots. The change in enthalpy (144.88–405.42 kJ mol−1) and Gibb's free energy (176.98 and 182.21 kJ mol−1) implied the endothermic nature and non-spontaneity of MDP pyrolysis. Whereas ΔS values were negative in the conversion range (0.05–0.3) indicating that the process was spontaneous at initial conversions. The kinetic and thermodynamic analysis results confirm the suitability of milk dust powder as a potential candidate for energy conversion through pyrolysis.

Herein, a novel magnetic cross-linked chitosan CS-BA@Fe3O4 was rationally synthesized by cross-linked with epichlorohydrin and coated with Fe3O4 to the acylated chitosan, which was prepared by the reaction of chitosan with benzenetricarboxylic anhydride. The as-obtained absorbent was characterized by FTIR, XRD, VSM, TGA, TEM, BET, SEM and EDS. The results showed that the maximum adsorption capacities of CR and CV were 471.46 ± 16.97 mg/g and 515.91 ± 25.12 mg/g at 318.15 K, respectively. The main adsorption mechanisms were H-bonding and electrostatic interaction. The kinetic data were in good agreement with the pseudo-second-order model and closed to adsorption equilibrium at 30 min. Thermodynamic studies showed that the adsorption on CS-BA@Fe3O4 were spontaneous and endothermic. More importantly, the adsorbent exhibited excellent regeneration properties after 6 cycles and remarkable stability under harsh environments including strong acid, strong alkali, multi-salt and mixed dyes conditions. Therefore, abundant efforts revealed a broad application prospect of CS-BA@Fe3O4 in water remediation.

Dyestuff in industrial wastewater continues to entail environmental pollution and thus developing an adsorbent with superior adsorption performance is urgently required for the survival of future generations. In this work, a novel Co– and H4dbp based metal-organic framework (MOF, denoted as Co-MOF) adsorbent was developed for the removal of methylene blue (MB) from aqueous solution. Hydrothermal synthesis was employed for the fabrication of the Co-MOF with phosphonic acid organic ligand. X-ray diffraction, Fourier-transform infrared spectroscopy, field emission-scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and N2 adsorption-desorption isothermal analysis were utilized for Co-MOF characterization. MB adsorption by as-prepared adsorbent obeys pseudo-second-order adsorption kinetics and follows Langmuir isotherm model with the maximum adsorption capacity of 147.99 mg g−1, which is superior to other analogies. Furthermore, the recoverability of this adsorbent material was astonishing with an excellent MB removal capacity of 89.34 % of initial dye concentration after the fifth cycle. The thermodynamic parameters affirm that this adsorption process exhibits a spontaneous endothermic process with sufficient molecular randomness due to the adsorbent-adsorbate interaction suggesting a great potentiality as an adsorbent to be used for industrial wastewater treatment to mitigate the environment.

Today, a variety of pesticides are used to fight plant pests in the world. The entry of these resistant pollutants into water resources can have devastating effects on human health and the environment, hence their removal from the environment is a vital task. In the present work, the magnetic iron-based metal-organic framework (Fe3O4/MIL-101 (Fe)) was synthesized by a simple and feasible method and characterized by FT-IR, XRD, BET, FESEM, TEM, TGA, and VSM techniques. The synthesized nanocomposite was successfully applied for the removal of fenitrothion (FEN) pesticide from the aqueous solutions. The isothermal and kinetic models were also investigated. The Langmuir isotherm model (type I) and pseudo-second-order kinetic model were more consistent in the adsorption process. The thermodynamic parameters of fenitrothion sorption were also calculated. The results revealed that the adsorption of fenitrothion onto Fe3O4/MIL-101 (Fe) was spontaneous and endothermic under optimized conditions. Moreover, the removal efficiency of FEN was predicted using the developed fuzzy logic model. Four input variables including the initial concentration of FEN (mg·L−1), pH of the solution, adsorbent dosage (mg), and contact time (min) versus removal efficiency as output were fuzzified by the usage of an artificial intelligence-based method. The fuzzy subsets consisted of Triangular and Trapezoidal membership functions (MFs) with six levels and a total of 23 rules in IF-THEN format which was applied on a Mamdani inference system. The obtained coefficient of determination value ( R pred 2 = 0.98205) proved the excellent accuracy of the fuzzy logic model as a powerful tool for the prediction of FEN removal efficiency.

This study aimed to determine the best adsorbent among Moringa oleifera-derived activated carbon (AC), eggshell-derived CaO nanoparticles and CaO/Fe3O4 for sodium (Na+) removal from aqueous media. In the first step, the appropriate adsorbent for sodium adsorption was determined among the three adsorbents, which the results showed that the AC had the highest sorption efficiency. Then, response surface methodology (RSM) was used to evaluate the impact of different factors on the Na+ ion sorption efficiency using the AC. The highest removal efficiency was obtained to be 95.91% at optimum conditions such as pH of 11, contact time of 45 min, temperature of 25 °C, sodium ion concentration of 900 mg/L, and adsorbent dosage of 5 g/L. Also, the best conditions using the genetic algorithm was obtained at contact time of 94.97 min, adsorbent dosage of 3.52 g/L, Na+ ion concentration of 939.92 mg/L and pH value of 10.92. Moreover, the maximum sorption capacity using the Langmuir model was obtained to be 249.67 mg/g, which was a significant value. Besides, the equilibrium and kinetic studies indicated that the experimental data of sodium adsorption process were fitted well with the Langmuir isotherm model and the pseudo-second-order kinetic model, respectively. Furthermore, the thermodynamic study indicated that the sorption process was endothermic. Generally, among the three adsorbents used, activated carbon with a high removal efficiency and significant sorption capacity can be considered as a promising adsorbent for the removal of sodium from wastewater on an industrial scale.

The freshwater alga Spirogyra crassa was subjected to pyrolysis to investigate its potential use as a bioenergy feedstock. To do so, the pyrolysis behavior of the Spirogyra crassa under thermogravimetric scale was first determined at the temperature range from 25 to 800 °C, with three slow heating rates (5, 10, and 20 °C min−1) under an oxygen-free atmosphere. It is assumed that the pyrolysis of Spirogyra crassa occurs in four reaction steps with different kinetic triplets. The activation energy was obtained for each reaction step by concurrent use of four isoconversional methods (Friedman, Flynn-Wall-Ozawa, Kissinger-Akahira-Sunose, and Starink), with average values ranging from 120.6 to 217.0 kJ mol−1. Pre-exponential factors determined from the kinetic compensation effect were found to range between 6.88 × 107 and 7.54 × 1019 min−1. Master plot results indicated that the nth-order-based mechanisms described the pyrolysis behavior of organic matter and, subsequently, the pyrolysis behavior of inorganic matter follows Avrami-Erofeev nucleation mechanisms. According to the thermodynamics parameters, the pyrolysis of Spirogyra crassa verifies to be a non-spontaneous, endothermic, and complex conversion. The summative kinetic expression proposed from the estimated kinetic triplets is a satisfactory option for describing the pyrolysis kinetics of Spirogyra crassa, with a quality of adjustment above 93.3 %. In conclusion, the insights of this study confirm that Spirogyra crassa has considerable potential as a feedstock for bioenergy production, and could be used for engineering purposes in the design or simulation of large-scale pyrolysis reactors.

Herein, a low-cost and green adsorbent (Pect/AILP-Kal) was successfully synthesized from pectin modified with hybrid mixture of Azadirachta indica leaves and kaolin clay and further analyzed as an efficient adsorbent for sequestration of MB and CV dyes. Effect of the operational parameters, for instance concentration, temperature, dose, pH and contact time on adsorption characteristics were studied in detail. The optimum pH for sequestration of MB and CV was obtained at pH 7.5 with time of 180 min. Adsorption kinetics for MB and CV dyes was best followed with pseudo-second order. The equilibrium data showed that the Langmuir was best obeyed with an isotherm model. The endothermic and spontaneous nature was indicated by the positive ΔH° values and negative values of ΔG° calculated from the thermodynamic parameters. Breakthrough and exhaustive capacities were identified as being 16 and 76 (mg g−1) for MB while 20 and 72 (mg g−1) for CV dyes respectively. Desorption results showed that synthesized (Pect/AILP-Kal) nanocomposite can be reused upto fifth cycle successfully. In order to remove these hazardous dyes from aqueous solution, (Pect/AILP-Kal) nanocomposite can be utilized very effectively and economically.

Acid mine drainage is an extraordinarily acidic and highly heavy metal ion-contaminated leachate, seriously threatening the environment. In this work, an industrial solid waste of steel slag is the adsorbent to remediate the simulated acid mine drainage containing a large amount of Fe(II) ions. Due to the excellent physicochemical properties and structures, steel slag exhibited remarkable Fe(II) removal performance. Its maximum removal efficiency was up to 100%. The initial pH, the dosage and particle size of steel slag, and initial concentration of heavy metal ions on Fe(II) removal efficiency were determined. The pseudo-second-order model and Freundlich isotherm model well described the adsorption behavior of steel slag, implying that the adsorption of Fe(II) by steel slag was mainly multilayer chemisorption. The thermodynamic study demonstrated that the adsorption process was endothermic and spontaneous; the enthalpy change was calculated to equal 91.21 kJ/mol. Mechanism study showed that the entire removal process of Fe(II) by steel slag was completed by electrostatic adsorption, chemical precipitation, and surface complexation in cooperation, and the chemical precipitation was the dominant mechanism. Meaningfully, this study provides a valuable strategy and path for engineering applications of AMD remediation by steel slag, which is prospective as an ideal candidate for Fe(II) ions elimination, inspiring the future development of "Treating the wastes with wastes."