Langmuir-Hinshelwood Kinetic Model Research Articles

Quaternary In0.15Sn0.85(Se0.95S0.05)2 crystal: Synthesis, characterization, and its multiple applications

The applications of quaternary In0.15Sn0.85(Se0.95S0.05)2 (ITSS) crystals were investigated as a near-infrared (NIR) optoelectronic switching device, vacuum pressure sensor, and photocatalyst. The remarkable photoresponse is demonstrated by the NIR crystal-based ITSS photodetector for various applied external biasing voltage. The NIR photodetector exhibits fast switching with a photoresponsivity of 147 mA/W. The crystals were investigated as a vacuum pressure sensor in the vacuum range ranging from 0 mbar to −1033 mbar as a function of electrical resistance. The n-type grown quaternary crystals have a direct optical bandgap of 1.38 eV. The photocatalytic activity was assessed by varying the concentration of methylene blue (MB) and the characteristics of the photocatalytic process were computed using the Langmuir-Hinshelwood kinetic model. Raman spectroscopy was performed on the grown crystals at temperatures ranging from 98 K to 448 K, with a step of 50 K to study the structural stability. The Lorentzian function was fitted to the experimental data to determine the peak width and peak position. The quaternary ITSS crystals were grown by the mechanical alloying process. The stoichiometry and layered growth mechanism of grown ITSS crystals were confirmed through energy dispersive X-ray spectroscopy (EDS) with mapping and field emission scanning electron microscopy (FESEM), respectively. The hexagonal crystal structure was characterized by the powder X-ray diffraction (PXRD) pattern, and the electrical resistance was studied as a function of temperature.

Advancement of visible light-driven photocatalytic degradation of dimethyl sulfide by Zn doped rGO/TiO2

In this study, visible light-driven photocatalytic degradation of dimethyl sulfide (DMS) by nanocomposite photocatalyst was achieved through doping TiO2 with reduced graphene oxide (rGO) and various contents of Zn via solvothermal method. Doping of Zn led to formation of oxygen defects and presence of Ti3+ which further promoted photocatalytic activity. After modification, formation of lower level band gap between VB and CB reduced required energy for electron excitation and accelerated light energy utilization. Besides, the presence of surface oxygen vacancies enhanced photocatalytic activity via adsorption of exoteric oxygen. The best DMS conversion (almost 50 %) was performed by 0.1rGO/Zn1TiO2 under typical indoor environment at 60 % RH. Declining of relative humidity to below 10 % improved photocatalytic degradation of DMS due to lower competitive adsorption of water vapor. The best fitting by Langmuir-Hinshelwood kinetics model 4 also supported the occurrence of competitive adsorption with water vapor. Moreover, detection of generated intermediates was used in development of proposed reaction mechanism. Thus, the discussion on DMS photocatalytic degradation over Zn/rGO/TiO2 could be comprehensively conducted from the preparation, characterization, stability test, proposed reaction mechanism, and kinetic study.

Green synthesis of AgCoFe2O4@Ch/AC as a recyclable, magnetic nanohybrid heterogeneous catalyst in photodegradation of ceftriaxone from aqueous solutions with effluent bioassay

Ceftriaxone (CFTR) is among the most commonly used antibiotics in the treatment of different types of bacterial infections and widespread pneumonias. It was also known as one of the most frequently prescribed antibiotics during the Corona pandemic. This drug has a longer half-life than other antibiotics. In this research, the heterogeneous magnetic nanophotocatalyst AgCoFe2O4@Chitosan(Ch)/activated carbon (AC) was synthesized by co-precipitation method under microwave waves. The catalyst structure was characterized by XRD, FTIR, FESEM, EDS, mapping, line scan, BET, VSM and DRS analyzers. Then, the effect of pH, CFTR concentration, nanophotocatalyst dose and irradiation time on the photocatalytic process efficiency was investigated. The analyses showed that the catalyst was synthesized on a nanometer scale, high surface area (60.044 m2/g), high magnetic strength (Ms = 10.39 emu/g) and appropriate optical activity with band gap (3.1 eV). The highest removal efficiency at pH = 3, CFTR concentration of 5 mg/L, dose of 0.24 g/L, and irradiation time of 60 min was obtained at 98.8% and 79.01% for synthetic and real wastewater samples, respectively. The reaction kinetics followed the pseudo-first-order and Langmuir–Hinshelwood kinetic models with KC = 0.23 mg/L min and KL−H = 0.168 L/mg. The recovered catalyst was able to remove CFTR with an efficiency of 80.16% after 4 reuse cycles. The results of scavenger radical tests showed that the main active radical species was ^{ cdot } {text{OH}}. The obtained results from the effluent toxicity on the germination index of lettuce, watercress, radish and tomato seeds showed a significant reduction in the environmental hazards of the effluent. Due to the high efficiency, this nanophotocatalyst can be used for the treatment of pharmaceutical and hospital wastewaters, and the effluent has the least toxicity for the environment.

Kinetics of ester-105 degradation by La/TiO2 photocatalysis

Lanthanum-doped titanium (La/TiO2) nano-photocatalysts were prepared using the sol-gel method and characterized by X-ray diffraction (XRD), zeta potential, and low-temperature nitrogen adsorption analyses. Ester-105, a flotation collector from beneficiation wastewater, was chosen as the target pollutant. The influence of the initial ester-105 concentration, pH, and photocatalyst dosage on the photocatalytic degradation of ester-105 was investigated. To examine the kinetics of the adsorption and photocatalytic degradation of ester-105, a Langmuir adsorption model and Langmuir-Hinshelwood kinetic models were established and discussed. The synthesized photocatalyst comprised anatase-phase TiO2, with an isoelectric point of pH = 6.5, specific surface area of 56.1626 m2·g−1, and average pore size of 7.78 nm. The maximum adsorption and the adsorption equilibrium constant of La/TiO2 for ester-105 were determined as 0.338 mg·g−1 and 1.008 L·mg−1, respectively. The first-order kinetic reaction rate constant (k) exhibited a linear relationship with the initial ester-105 concentration. The optimal pH for ester degradation was theoretically determined to be 6.95, and the optimum photocatalyst dosage was found to be 0.2739 g·L−1. Experiments confirmed that the photocatalytic degradation of ester-105 using La/TiO2 followed the Langmuir-Hinshelwood kinetics model, thereby providing a theoretical foundation for the photocatalytic degradation of ester-105 for industrial application.

Survey of catalytic performance of TiO2 via coupling with ZSM-5 Zeolite under UV light for activation of peroxymonosulfate Applied towards Orange II (OII) degradation

Background: The widespread presence of organic dyes in the various industries’ effluent such as paper, textile, and clothing has led to significant environmental pollution. Titanium oxide (TiO2 ) nanoparticles immobilized on zeolite (ZSM-5) were investigated under UV light for activation of peroxymonosulfate (PMS) for photocatalytic degradation of Orange II (OII) dye in aqueous solutions. Methods: In this study, the photocatalyst used was prepared by immobilizing different amounts of TiO2 nanoparticles on ZSM-5. Characterization analyses including X-ray diffractometer (XRD), Fourier transform infrared (FTIR), BET, scanning electron microscope (SEM), and energy dispersive X-ray spectroscopy (EDS) were performed on the synthesized samples. Then, the effect of various parameters, such as TiO2 nanoparticles loading onto the ZSM-5, pH, contact time, dye concentration, and TiO2 / ZSM-5 dosage, is investigated for the removal of OII as a model molecule under the UV irradiation with 15 W power. Results: The highest removal percentage of OII dye (97.44%) was obtained in the optimal operating conditions of pH=3, the initial dye concentration=5 ppm, amount of TiO2 /ZSM-5=10 mg/L, amount of PMS=50 mg/L, and reaction time=120 minutes. The Langmuir–Hinshelwood kinetics model fitted with the experimental data. Conclusion: The obtained results of this research showed that PMS can be used as a suitable oxidant activated with ZSM-5/TiO2 nanocomposite in OII degradation in different water environments, by optimizing the effective operating factors.

Integration of WO3-Doped MoO3 with ZnO Photocatalyst for the Removal of 2-Nitrophenol in Natural Sunlight Illumination

Environmental contamination has become the most pressing issue in recent years. The value of clean water to mankind has sparked interest in heterogeneous photocatalysis. In this study, a novel photocatalyst has been synthesized by integrating WO3-doped MoO3 (WDM) and ZnO through composite formation. The composite nature of the synthesized photocatalyst was confirmed due to the presence of hexagonal ZnO and orthorhombic WDM phases in XRD pattern and scanning electron micrographs. Solid-state absorption spectra and a bandgap analysis showed that WDM-spectral ZnO’s response was better than that of pure ZnO. PL and EIS unveiled the effective role of WDM in suppressing the e−–h+ recombination process and charge-transfer resistance, respectively, in ZnO. The photocatalytic studies showed that WDM-ZnO was able to remove ~90% of 30 ppm 2-nitrophenol (2-NP) with a rate of 1.1 × 10−2 min−1, whereas ~65% 2-NP was removed by ZnO (6.1 × 10−3 min−1 rate) under the exposure of natural sunlight (800 × 102 ± 100 lx). Moreover, ~52% higher total organic carbon (TOC) removal was observed by WDM-ZnO as compared to ZnO. The photocatalytic removal of 2-NP by the produced photocatalysts followed the Langmuir–Hinshelwood kinetic model, as shown by the kinetic studies. The reactive oxygen species (ROS)-trapping established that the photocatalytic removal mechanism of 2-NP over WDM-ZnO in sunlight illumination was mainly triggered by the superoxide anion (O2•−) radical, however, the minor role of hydroxyl (•OH) radicals cannot be completely ignored.

High-capacity adsorption of hexavalent chromium by a polyaniline-Ni(0) nanocomposite adsorbent: Expanding the Langmuir-Hinshelwood kinetic model

A nanocomposite of 2-napthalenesulfonic acid doped-polyaniline decorated with zero valent nickel nanoparticles (PANI-NSA@Ni0), was considered for the removal of hexavalent chromium from synthetic effluent. Adsorption conditions (pH, dose) were optimised, and parameters necessary for the design of PANI-NSA@Ni0-based adsorption equipment (adsorbent capacity, kinetic constants, etc.) were estimated from batch adsorption experiments. PANI-NSA@Ni0 successfully achieves total hexavalent chromium removal at a dose of 0.6 g/L, corresponding to a Cr(VI) loading of 333.3 mg/g, and when 2 < pH < 3. The combined monolayer capacity of the adsorbent was found to be 820.5 mg/g, with equilibrium adsorption behaviour adequately described by a modified dual-site Langmuir isotherm model. The adsorption of Cr(VI) by PANI-NSA@Ni0 was found to be largely unaffected by the presence of competing ions. Following adsorption, successful recovery of 95.5% of adsorbed chromium was achieved by employing HNO3 followed by NaOH as desorption agents, however this resulted in ≈ 88% loss in adsorption capacity for the subsequent cycle. After redeposition of Ni0 on the desorbed material, the adsorbent’s capacity was restored to 92% of the original capacity. An adsorption-coupled reduction mechanism, followed by the precipitation of Cr(OH)3, is believed to be the major mechanistic process responsible for Cr(VI) removal. Based on the proposed mechanism, a modified Langmuir-Hinshelwood adsorption-coupled reduction kinetic model was used to successfully describe the adsorption kinetics. The modified Langmuir-Hinshelwood adsorption-coupled reduction kinetic model produces rate constants which are independent of operating conditions such as initial pollutant concentration and adsorbent dose, and adequately describes the system’s equilibrium using the same rate constants. Thermodynamic parameters calculated using the best fitting isotherm model and novel kinetic model were both in agreement, and revealed that the adsorption process proceeds spontaneously and endothermically, with an increase in randomness at the solid–liquid interface and potential changes in the structure of the adsorbent/adsorbate.

Mechanistic view of MoS2 confined chitosan-polyaniline hybrid composite for the photo-oxidation of cationic dyes

In this article, we describe the formulation of polyaniline-chitosan/MoS2 (PANI-CS @MoS2) blended composite and evaluated its efficiency to degrade the dye molecules Rhodamine B (RhB) and Malachite Green (MG) under visible light. In the photocatalytic mechanism, the CS acts as an electron carrier and binding agent during the oxidation reaction to decrease the recombination of electrons and holes generated by the irradiation of light. FTIR, XPS, XRD, TG, Zeta Potential, UV, SEM, AFM and TEM were used to characterize the PANI-CS@MoS2 composite after it had been synthesized. For the degradation analysis, 30 mg/L concentrations of 50 mL MG and RhB dye solutions were used. The recommended dosage of the composite was 100 mg. For MG and RhB dyes, the colour removal rates were 96.2 % and 91.5 %, respectively, under exposure to visible light and at the pH ranges of 8–11. After being exposed to visible light for 60 min, the whole decay process was accomplished. The photocatalyst offers great extensibility up to five iterations. The Langmuir-Hinshelwood kinetic model governs the rate of dye molecules degradation. The result of the study revealed that the PANI-CS@MoS2 composite matrix perhaps be a trustworthy and practical substrate for the efficient refinement of dye-deteriorated water⁠⁠⁠⁠⁠⁠⁠.

Characterization and photocatalytic activity of ZnO nanoparticles by green synthesis method

In this work, zinc oxide nanoparticles have been synthesized by green synthesis technique using sodium hydroxide and zinc nitrate, with and without calcination. In this research, Myrtus communis extract was used along with three different alkaline molar ratios (0.5 M, 1 M, and 2 M) to successfully synthesize ZnO nanoparticles (NPs) from the same precursor. In the calcined samples, this process was carried out at 800 °C. X-ray diffraction, scanning electron microscopy, and diffuse reflectance spectra were used to explore the structural, morphological, and optical features of ZnO nanoparticles. The XRD peaks confirm the successfully synthesized hexagonal wurtzite zinc oxide and are in full conformity with the published data of the JCPDS: 36–145. With high absorption peaks at about 370 nm wavelength, UV-Vis spectroscopy further supported the ZnO NPs' strong optical properties. Morphology and topography were discovered by SEM analysis and displayed the evolution of ZnO nanowires around 10 µm length with calcination. No nanowire formation was observed in the uncalcined samples. The results demonstrated that the degradation efficiency of ZnO nanoparticles is dependent primarily on the UV exposure time and morpholgy. When ZnO with 1 M NaOH calcined at 800 °C is used, the maximum MB degradation of about 99% is achieved. Methyl blue photodegradation follows the first-order Langmuir–Hinshelwood kinetic model.

Facile “Green” synthesis of a novel Co–W–B catalyst from Rheum ribes shell extract and its effect on sodium borohydride hydrolysis: Kinetic mechanism

The present investigation aimed to assess the influence of the Co–W–B NPs catalyst on the process of sodium borohydride hydrolysis. The study involved the synthesis of Co–W–B NPs through the utilization of an eco-friendly green synthesis extract derived from the Rheum ribes shell in conjunction with the chemical reduction technique for catalyst production. The investigation of catalysts' structure and surface morphology was conducted through the utilization of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDX), and Fourier transform infrared spectroscopy (FTIR) techniques. The average particle size was determined to be 35 nm in TEM analysis. The presence of Co–W–B nanoparticles and their elemental composition % were determined through EDX analysis, revealing values of 63.9% (Co), 31.89% (C), 1.75% (B), and 2.46% (W) within the nanoparticle. The manufactured Co–W–B catalyst's use for hydrolysis of sodium borohydride was studied under various conditions, including different concentrations of NaOH and NaBH4, different amounts of catalyst, and different temperature parameters. The hydrogen production rate for the Co–W–B NPs catalyst in NaBH4 hydrolysis was determined to be 5367 mLg−1min−1 at 30 °C. The study involved the determination of TOF values for a catalyst composed of Co–W–B NPs, which were subjected to varying temperatures. The activation energies were determined through the utilization of the n-th order and Langmuir-Hinshelwood kinetic models and subsequently calculated using the Arrhenius equation, resulting in values of 35.36 and 31.70 kJ/mol, respectively. The values of enthalpy and entropy, ΔH and ΔS, were determined through the utilization of Eyring's equation, 18.49 kJ/mol and −80.7 J/mol.K, respectively.

Effect of light alkanes and aromatics on decalin dehydrogenation over noble metal catalysts: A new strategy for the development of naphthalene-based LOHCs

The use of the naphthalene/decalin pair as a liquid organic hydrogen carrier has gained increasing interest due to its high hydrogen loading capacity and industrial availability. However, a major challenge in its application is the fact that naphthalene is a solid at ambient conditions, leading to the solidification of the unloaded organic carrier. To address this limitation, small amounts of light organics, such as monoaromatics or cycloalkanes, can be added. In this study, we investigated the dehydrogenation of decalin over various supported precious catalysts (Pt, Pd, Rh, Ru; supported on both activated carbon and alumina) in a stirred batch reactor at 200 °C. Initial experiments were conducted with pure decalin, and we found that Pt/C provided the best performance. Subsequently, we studied the dehydrogenation of decalin in mixtures with different solvents (cyclohexane, methylcyclohexane, benzene, and toluene in the concentration range of 10–40% of the light hydrocarbon). Our results show that the addition of cycloalkanes did not affect the main reaction, while aromatic compounds exhibited weak inhibition. A Langmuir-Hinshelwood kinetic model has been proposed for predicting this behavior, taking into account the significant inhibitory impacts of naphthalene and, when present, the aromatic additive.

Study of norfloxacin degradation by advanced oxidation process using UV/TiO2/H2O2 in an annular reactor

Norfloxacin (NFX) residual was frequently found in domestic wastewater, sewage treatment plants, hospital wastewater, and surface water like lakes and rivers. This threatens the ecological balance of the environment. Moreover, normal biological treatment methods (including membrane bioreactor - MBR) are not feasible for the removal of NFX. In this study, the degradation of NFX through advanced oxidation processes (AOPs) utilising UV/TiO2 and H2O2 as reagents in a laboratory-scale tubular reactor system was conducted. The degradation reactions of NFX could be represented by the Langmuir-Hinshelwood kinetic model. The influence of factors, including TiO2and H2O2 concentrations, UV irradiation intensity, and hydrodynamic conditions (specifically, Reynolds number), on the apparent reaction rate constant (kapp) was evaluated. The results demonstrated that the advanced oxidation process employing the combined reagents of UV/TiO2/H2O2 under the following reaction conditions: TiO2 and H2O2concentrations of 0.2 g/l and 0.0492 mol/l, UV irradiation intensity of 225 W/m2, and Reynolds number of 6700, achieved an apparent degradation reaction rate constant for NFX of 0.052 min-1.

A novel ternary Ti-V-Bi oxide photoelectrocatalyst in advanced oxidation process

Photoelectrocatalytic pollutant degradation is one of the most promising advanced oxidation processes for wastewater treatment. However, its efficiency dramatically depends on the development of photoelectrocatalyst materials. Therefore, here, ternary Ti0.2-Vx-Bi(0.8−x)-oxides (x = 0.15, 0.3, 0.4, 0.5, and 0.65) were applied as the photoelectrocatalysts for pollutant degradation. The photoelectrocatalysts were synthesized by a dip-coating thermal decomposition (DCTD) method. The physical and optical characteristics of photoelectrocatalysts were analyzed by XRD, FE-SEM, EDS, PL, and DRS tests. The photo/electrochemical behavior of samples was studied by LSV, EIS, and chronoamperometry with and without visible light illumination. The activity of samples was investigated by photocatalytic, electrocatalytic, and photoelectrocatalytic treatment of methyl orange and rifampin solutions under visible light irradiation. The kinetics of photocatalytic, electrocatalytic, and photoelectrocatalytic degradation processes was investigated by the Langmuir-Hinshelwood (L-H) kinetic model. Moreover, the mineralization extent of rifampin was studied by COD test. The results pointed to the optimum composition of ternary Ti0.2V0.4Bi0.4-oxide, in terms of both photocurrent and degradation time, which could completely degrade methyl orange and rifampin solutions in less than 15 min at a current density of 5 mA/cm2 under visible light irradiation. The superior performance of Ti0.2V0.4Bi0.4-oxide was attributed to its smaller particle size (larger surface area), lower band gap (2.1 eV), the lower recombination rate of e-/h+ pairs, and lower charge transfer resistance than the other compositions. The high activity and stability of Ti0.2V0.4Bi0.4-oxide introduce it as an efficient photoelectrocatalyst for pollutant degradation by the advanced oxidation process (AOP).

Heterogeneous Sono-Fenton like catalytic degradation of metronidazole by Fe3O4@HZSM-5 magnetite nanocomposite

In this research, Fe3O4@HZSM-5 magnetic nanocomposite was synthesized via a coprecipitation method for metronidazole (MNZ) degradation from aqueous solutions under ultrasonic irradiation which showed superb sonocatalytic activity. The synthesized magnetite nanocomposite was characterized by using field-emission scanning electron microscope-energy dispersive X-ray Spectroscopy, (FESEM-EDS), Line Scan, Dot Mapping, X-ray diffraction (XRD), vibrating sample magnetometer (VSM), and Brunauer-Emmett-Teller (BET). To investigate the sonocatalytic activity of the Fe3O4@HZSM-5 magnetite nanocomposite, the sonocatalytic removal conditions were optimized by evaluating the influences of operating parameters like the dosage of catalyst, reaction time, pH, the concentration of H2O2, MNZ concentration, and pH on the MNZ removal. The MNZ maximum removal efficiency and TOC at reaction time 40 min, catalyst dose 0.4 g/L, H2O2 concentration 1 mM, MNZ initial concentration 25 mg/L, and pH 7 were achieved at 98% and 81%, respectively. Additionally, the MNZ removal efficiency in the real wastewater sample under optimal conditions was obtained at 83%. The achieved results showed that using Langmuir-Hinshelwood kinetic model KL-H = 0.40 L mg−1, KC = 1.38 mg/L min) can describe the kinetic removal of the process. The radical scavenger tests indicated that the major reactive oxygen species were formed by hydroxyl radicals in the Sono-Fenton-like process. Evaluation of the nanocomposite reusability showed an 85% reduction in the MNZ removal efficiency after seven cycles. Based on the results, it can be concluded that Fe3O4@HZSM-5 were synthesized as magnetic heterogeneous nano-catalysts to effectively degrade MNZ, and the observed stability and recyclability demonstrated that Fe3O4@HZSM-5 was promising for the treatment of wastewater contaminated with antibiotics.

Positive roles of microwave irradiation in hydrogen production from hydrolysis of sodium borohydride using iron oxide catalyst synthesized with watermelon seed peel extract by green method

This study reported the activities of WSP-FeO nanoparticles catalysts synthesized by the green synthesis method using watermelon seed peel (WSP) extract in sodium borohydride hydrolysis. The activities of the synthesized nanoparticles catalyst in the hydrolysis of sodium borohydride at different microwave irradiation, solution temperatures, catalyst amounts, NaBH4 concentrations, and sodium hydroxyl concentrations were evaluated. The hydrolysis kinetics of NaBH4 in the presence of WSP-FeO-NPs catalysts were determined according to the nth-order and the Langmuir-Hinshelwood kinetic models. The activation energies were calculated to be 18.98 kJ/mol and 18.96 kJ/mol, respectively. WSP-FeO nanoparticles were characterized by FTIR, TEM, EDX, SEM, and XRD analysis to determine their structural and morphological properties. According to the XRD and TEM analysis results, the nanoparticles were very pure and well crystalline, with particle diameters between 8.9-18.5 nm and 6–12 nm.

Improving the Degradation Kinetics of Industrial Dyes with Chitosan/TiO2/Glycerol Films for the Sustainable Recovery of Chitosan from Waste Streams

This study investigates the potential of a combined photocatalysis–adsorption approach to effectively degrade near wash yellow (NWY), a commonly used and highly persistent dye in the textile industry, notorious for its challenging treatment and removal from wastewater due to its colorfastness. A chitosan–glycerol (CTiG) film combined with titanium dioxide was examined in both batch and continuous-flow experiments under visible solar irradiation. The results show that this combination was more effective than a pure chitosan film (60%) or chitosan–glycerol film (63%), with up to 83% degradation of NWY achieved in just 60 min of visible solar irradiation. The kinetics of the film were evaluated using both pseudo-first-order and Langmuir–Hinshelwood kinetic models. The rate constant values (k, min−1) decreased with increasing NWY concentration from 20 to 80 mg/L, and k was found to be greater than twice as high under visible solar irradiation as it was in the dark. The Langmuir–Hinshelwood model’s KLH (reaction rate constant) and KL (adsorption coefficient) values were 0.029 mg/L·min and 0.019 L/mg, respectively. The optimal conditions for NWY degradation were found to be 4% TiO2 to chitosan ratio, glycerol/chitosan ratio of 40%, and a pH of 7. In the continuous-flow model, the CTiG film was submerged in an 8 L NWY solution (80 mg/L) and degraded at a rate of 22.6 mg NWY/g film under natural sunlight. This study contributes to the development of effective and sustainable methods for the degradation of dyes from textile industry wastewater.

Transition metal doped CeO2 for photocatalytic removal of 2-chlorophenol in the exposure of indoor white light and antifungal activity.

Besides natural sunlight and expensive artificial lights, economical indoor white light can play a significant role in activating a catalyst for photocatalytic removal of organic toxins from contaminated water. In the current effort, CeO2 has been modified with Ni, Cu, and Fe through doping methodology to study the removal of 2-chlorophenol (2-CP) in the illumination of 70W indoor LED white light. The absence of additional diffractions due to the dopants and few changes such as reduction in peaks' height, minor peak shift at 2θ (28.525°) and peaks' broadening in XRD patterns of modified CeO2 verifies the successful doping of CeO2. The solid-state absorption spectra revealed higher absorbance of Cu-doped CeO2 whereas a lower absorption response was observed for Ni-doped CeO2. An interesting observation regarding the lowering of indirect bandgap energy of Fe-doped CeO2 (∼2.7eV) and an increase in Ni-doped CeO2 (∼3.0eV) in comparison to pristine CeO2 (∼2.9eV) was noticed. The process of e -- h + recombination in the synthesized photocatalysts was also investigated through photoluminescence spectroscopy. The photocatalytic studies revealed the greater photocatalytic activity of Fe-doped CeO2 with a higher rate (∼3.9 × 10-3min-1) among all other materials. Moreover, kinetic studies also revealed the validation of the Langmuir-Hinshelwood kinetic model (R2 = 0.9839) while removing 2-CP in the exposure of indoor light with a Fe-doped CeO2 photocatalyst. The XPS analysis revealed the existence of Fe3+, Cu2+ and Ni2+ core levels in doped CeO2. Using the agar well-diffusion method, the antifungal activity was assessed against the fungus M. fructicola and F. oxysporum. Compared to CeO2, Ni-doped CeO2, and Cu-doped CeO2 nanoparticles, the Fe-doped CeO2 nanoparticles have outstanding antifungal properties.

Effect of environmentally friendly and efficient metal-free hydrochars as catalysts on sodium borohydride hydrolysis

Environmentally friendly, metal-free catalysts are important to synthesize and use, as are catalysts made from biomass-based. This study aims to obtain hydrochars from pine cones and rheum ribes shells by the hydrothermal method and use this hydrochar as a catalyst in sodium borohydride hydrolysis.The characterization of the synthesized catalyst hydrochars was carried out by XRD, BET, SEM, EDX, ICP-OES and FTIR analyses. X-ray diffraction analysis of pinecone hydrochar and rheum ribes shells hydrochar has revealed that they are both amorphous and crystalline in structure. The BET surface areas of the two hydrochars are 1.6 m2/g and 19.01 m2/g, respectively. The activity of hydrochars on the hydrolysis of sodium borohydride was evaluated under microwave irradiation at different temperatures, catalyst amounts, and different microwave powers. The hydrolysis kinetics of NaBH4 in the presence of pine cone and rheum ribes shells hydrochars catalysts were determined according to the nth-order and the Langmuir-Hinshelwood kinetic models. The activation energies for the rheum ribes shells and pine cone hydrochars catalysts were calculated to be 88.29 kJ/mol and 78 kJ/mol, respectively. It was concluded that hydrochar prepared from waste material extract through the eco-friendly green synthesis method is promising for the hydrolysis of NaBH4.

Efficient Photocatalytic Degradation of Methylene Blue Dye from Aqueous Solution with Cerium Oxide Nanoparticles and Graphene Oxide-Doped Polyacrylamide.

A cerium oxide nanoparticles (CeO2-NPs)/graphene oxide (GO)/polyacrylamide (PAM) ternary composite was synthesized through free-radical polymerization of acrylamide in the presence of CeO2 nanoparticles and GO in an aqueous system. The synthesized composite material was characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX) spectroscopy techniques and applied for the photocatalytic degradation of methylene blue (MB) dye from an aqueous solution. Tauc's model for direct transition was used to model for the optical band gap. The key operating parameters such as the amounts of CeO2-NPs and GO, pH, initial MB concentration, type of light irradiation, and contact time have been optimized to achieve the highest MB degradation percentage. The photocatalysis process was pH-dependent, and the optimum pH value was found to be 12.0. Under UV-A light, 90% dye degradation occurred in 90 min. The degradation of MB was also specified in terms of total organic carbon (TOC) and chemical oxygen demand (COD). Free-radical capture experiments were also performed to determine the role of radical species during the photocatalytic oxidation process. The photocatalytic process showed that the equilibrium data is in good agreement with the Langmuir-Hinshelwood kinetic model. A rate constant of 0.0259 min-1 was obtained. The hydrogel was also tested to assess its reusability, which is an important key factor in practical wastewater treatment. The photocatalytic activity only decreased to 75% after nine uses.

RGO doped S0.05N0.1/TiO2 accelerated visible light driven photocatalytic degradation of dimethyl sulfide and dimethyl disulfide

In this study, modification of TiO2 was carried out by doping of non-metal elements (S and N) and various contents of reduced graphene oxide (rGO) for photocatalytic degradation of dimethyl sulfide (DMS) and dimethyl disulfide (DMDS). Among the tested photocatalyst, 0.1wt%rGO/S0.05N0.1TiO2 had the best photocatalytic degradation efficiencies for both DMS and DMDS. Reduction of band gap and increment in surface area might be related to the improvement in photocatalytic activity. Examination was followed by the study of various parameters influence, reaction kinetics, and proposed reaction mechanism using 0.1wt%rGO/S0.05N0.1TiO2. Dry and 1% relative humidity in gases promoted photocatalytic activity yet higher water vapor contents led to adsorption competition and reduced DMS and DMDS conversion. Langmuir-Hinshelwood kinetics model 4 presented the best suited result for photocatalytic degradation of DMS and DMDS using 0.1wt%rGO/S0.05N0.1TiO2. Furthermore, proposed reaction mechanism for each type of pollutant was assembled from byproducts analysis during the reaction.