Langmuir-Hinshelwood Equation Research Articles

Photocatalytic degradation of ciprofloxacin by using tannin-doped BaTiO3 catalyst

The aim of this study is to highlight the significance of ciprofloxacin degradation, a commonly used antibiotic in healthcare and agriculture, by synthesizing tannin-doped BaTiO3 (T-Ba) photocatalysts at various tannin amounts (0–50 wt%) and investigating their photocatalytic activity under both UV-A light and visible light irradiation. The impact of several parameters, including the initial concentration of ciprofloxacin, photocatalyst dosage, initial solution pH, and scavengers effect, on the photocatalytic activity was explored. The photocatalysts were characterized by FTIR, SEM, XRD, XPS, TEM, BET, PL and UV-DRS analysis. In the conducted studies, it was observed that the highest efficiency was achieved at 96 % under appropriate parameters. The kinetic study was conducted based on the Langmuir-Hinshelwood equations. According to stability tests, ciprofloxacin degradation was found as 92 % after the second cycle, while it was 50 % after the fifth cycle.

Enhancing photocatalytic efficiency with Mn-doped ZnO composite carbon nanofibers for organic dye degradation

<abstract> <p>In this study, Mn-doped ZnO composite carbon nanofibers (Mn-ZnO/CNFs) were prepared via a simple blending and electrospinning (ES) method, followed by a thermal treatment. These fibers were used to investigate the photocatalytic degradation of an organic dye under UV and visible light irradiation. The results showed that Mn-ZnO/CNFs were successfully prepared under the same conditions used for CNFs preparation conditions, which induced a morphological change from a smooth to a rough surface compared to the CNFs. Energy dispersive X-ray (EDX), x-ray diffraction (XRD), and x-ray photoelectron spectroscopy (XPS) analyses confirmed the formation of Mn-doped ZnO on the CNFs' surface. Furthermore, the addition of the catalyst significantly increased in the specific surface area, and a N<sub>2</sub> adsorption-desorption isotherm analysis revealed that all samples had mesoporous characteristics with a type IV isotherm index. The photocatalytic activity of the Mn-ZnO/CNFs carbonized at 650 ℃ using methylene blue (MB) dye as a model pollutant was investigated. All prepared samples effectively removed the MB with a degradation rate of 70-90%. The kinetic reaction rate was described using the simplified Langmuir-Hinshelwood equation. Overall, the CNFs and composites nanofibers developed through moderate thermal treatment processes possessed a high specific surface area and oxygen vacancy, enabling their potential use as adsorbents and as a catalyst support for reactions at room-to-elevated temperatures, as well as photocatalysts for the removal of organic contaminants.</p> </abstract>

Degradation of binary mixtures of water pollutants in a photocatalytic microreactor: Competitive kinetics with explicit radiation absorption effects

The photocatalytic degradation of 17-α-ethinylestradiol (EE2) and phenol in aqueous solutions was studied using a continuous flow, planar microreactor under simulated sunlight. A TiO2 thin film was employed as photocatalyst. The degradation rates of single compounds and binary mixtures were well described by the Langmuir-Hinshelwood equation, including competitive terms for the companion pollutant and the intermediate products, and the effect of photon absorption by the photocatalyst. The absorbed radiation in the microreactor was calculated from the optical properties of the TiO2 film and the application of the Net Radiation method. The estimation of the kinetic parameters was carried out by numerical integration of coupled mass balance equations for EE2 and phenol employing the Runge-Kutta method, and adjusting the kinetics parameters with a nonlinear least-squares solver. The objective of this routine was to minimize the sum of the squares of the differences between the simulated and experimental outlet concentrations of EE2 and phenol under different operating conditions. Using this approach, intrinsic kinetic parameters were obtained. The model was able to predict the degradation of both organic pollutants under different inlet concentrations, irradiation levels, and fluid flow rates. This methodology can be extended to assess the simultaneous degradation of multi-component systems.

CALCULATION OF THERMODYNAMIC AND KINETIC PARAMETERS OF CATALYTIC CRACKING REACTIONS ON LEWIS AND BRØNSTED ACID SITES

Link for citation: Nazarova G.Y., Ivashkina E.N., Maltsev V.V. Calculation of thermodynamic and kinetic parameters of catalytic cracking reactions on Lewis and Brønsted acid sites. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 7, рр. 214-225. In Rus. The relevance of the research is caused by the emerging necessity of developing a mathematical model to optimize the heterogeneous process of catalytic cracking. This tools should take into account both the chemical transformations of a wide range of hydrocarbon groups (different feedstock types), as well as the stages of adsorption, reactants diffusion, conversion of hydrocarbons on the catalyst surface, acid characteristics and pore size of the catalysts. The study of the hydrocarbon conversion patterns on Lewis or Brønsted acid sites using quantum-chemical modeling methods allow us to quantify the thermodynamic parameters of reactants adsorption, the kinetic parameters of carbocations formation and cracking on acid sites. These results are necessary to develop a mathematical model based on the of heterogeneous catalytic reaction mechanism. The aim of this work is to identify the level of quantum chemical theory and to determine the thermodynamic and kinetic parameters of reactants adsorption, carbenium ions formationand hydrocarbons cracking on Lewis and Brønsted acid sites. Methods: quantum-chemical modeling methods to optimize the molecular geometry of reactants and products of catalytic cracking reactions, calculate vibrational frequencies, thermodynamic parameters of adsorption and catalytic cracking of hydrocarbons and heteroatomic compounds with the participation of Bronsted and Lewis acid sites. Results. The chosen level of quantum-chemical theory allowed obtaining the results that are consistent with the laws of the process and the experimental reactivity of hydrocarbons in cracking reactions on acid catalysts. The thermodynamic parameters of the adsorption of C6–C16 hydrocarbons and thiophenes on Lewis and Brønsted acid sites were identified. We found that during the cracking of n-hexane on the Lewis acid site, the reaction is limited by the carbenium ion formation stage.The activation energy of this stage was 281,3 kJ/mol whereas the value for the cracking stage was 277,2 kJ/mol. Further study shows that the activation energy of carbenium ion formation from izohexane and C8–C10 alkanes with normal structure on the Lewis acid site was 257,6 and 279,2…277,9 kJ/mol. The most energetically favorable is the formation of carbocation from hexene at Brønsted acid sites (76,59 kJ/mol). The results of the work will be used to create a mathematical model of a heterogeneous process based on the Langmuir–Hinshelwood equations.

ZnO/g-C3N4 S scheme photocatalytic material with visible light response and enhanced photocatalytic performance

ZnO/g-C3N4 composite photocatalyst is prepared by ultrasonic dispersion method for Rhodamine B (RhB) degradation from wastewater. The characterization results of the ZnO/g-C3N4 indicate that ZnO nanoparticles are uniformly dispersed on the surface of two-dimensional g-C3N4 nanosheet. In addition, the existence of heterojunction between ZnO and g-C3N4 promotes the effective separation of photogenerated carriers and improves the photocatalytic activity of the ZnO/g-C3N4. The influence of ZnO/g-C3N4 dosage on the RhB photocatalytic degradation removal is investigated. The RhB photocatalytic degradation removal is 95.6 % and reaction rate constant is 0.0201 min−1 at addition amount of 4.0 g/L. The RhB photocatalytic degradation kinetics process is fitted by Langmuir-Hinshelwood equation. Compared with the difference between the peak positions of N1s, C1s, O1s and Zn2p in ordinary and in situ XPS spectra, the analysis result indicates that the transfer path of photoelectrons is from ZnO to the g-C3N4 under visible light irradiation. The RhB photocatalytic degradation mechanism conforms to the S-scheme mechanism combined with DFT calculation. ZnO/g-C3N4 still has good photocatalytic degradation activity after 5 cycles.

Modelling of photocatalytic CO2 reduction into value-added products in a packed bed photoreactor using the ray tracing method

This research suggests a comprehensive 3D model for modelling photocatalytic conversion of CO2 to methane, hydrogen and carbon monoxide in a packed bed reactor. This research includes two parts: designing the reactor's geometry using a new method in "blender" and using the computational fluid dynamics (CFD) technique to study and analyse the reaction, transport of phenomenon and light intensity through the reactor. Laminar flow, chemical reaction, mass transfer and optics physics were considered together to solve the equations. The surface reaction in the reactor follows a modified version of the Langmuir-Hinshelwood equation that evaluates the light profile in the reactor and the blockage of the catalyst's surface over time. Thus, a new method for 3D modelling light profiles in the reactor is introduced. The rate of reaction continues to increase with the pressure, and after 1 atm, the rate becomes steady. In the first 17 h, the methane rate is the highest, and then the carbon monoxide rate overcomes the methane rate. The rate of hydrogen is considerably lower than the other products. Changing pellets from spheres to Raschig rings causes growth in the probability density function (PDF) at the first moments. In methane's PDF, the amount of Raschig and sphere are 0.25 and 0.18, respectively, at the start of the reaction. Thus, the Raschig ring operates more effectively at the beginning moments of the process but eventually is outweighed after an hour by spherical particles. In the end, the validation of modelling and results were investigated with the aid of experimental data.

Assessment of back-side activation of titania thin film using a fixed-bed photocatalytic-reactor: Kinetic study, operating cost and ANN modeling

This work is concerned with construction, application and modeling of a thin-film fixed photocatalytic bed multi lamp photo-reactor as an organic pollutant treatment system. Five photocatalytic units were located in a cylindrical vessel with a recycling current. In each unit, a thin layer of titania nanoparticles was coated on the outer surface of a quartz tube which a UV lamp was installed inside it. By this configuration, the UV lamps irradiation can approach directly to the photocatalyst particles before penetration into the reaction media. The effect of initial pH, initial DR16 (as model pollutant) dosage, H2O2 (as auxiliary oxidant) concentration and number of applied activated photocatalytic units were studied. The process was monitored via the kinetic rate constant and operating cost factors. The photocatalytic degradation of DR16 molecules in the constructed multi lamp photo-reactor followed a pseudo-first-order kinetic, and well described by the Langmuir-Hinshelwood equation. Under the initial pH of 3, 150 mg/L of H2O2 and illumination of the five lamps, complete degradation of the target pollutant was achieved after 60 min. Under these conditions, the rate constant and operating cost were 0.078 min−1 and 1.13 US$/m3 respectively. The real photon flux inside the reactor and quantum efficiency of the photocatalytic degradation of DR16, using five turned on lamps, were evaluated as 10.84 × 10−6 (einstein.s−1) and 0.009 respectively Also, the photocatalytic process was well modeled (with mean square error of 16.81 ×10−5) by a three layered feed forward back propagation artificial neural network consists of trainlm as training function, 7 hidden neurons and tansig-tansig as transfer functions calibrated at 156th epoch.

PbS/ZIF-67 nanocomposite: novel material for photocatalytic degradation of basic yellow 28 and direct blue 199 dyes

BackgroundIn recently years, the significant focus of research was on the photocatalytic elimination of organic dye pollutants using semiconductor photocatalysis. In this study, the novel PbS/ZIF-67 nanocomposite was synthesized as a semiconductor photocatalyst for photodegradation of Basic Yellow 28 (BY28) and Direct Blue 199 (DB199) from wastewater. MethodThe prepared samples were characterized by FT-IR, XRD, SEM, TEM, and photoluminescence (PL) analysis. The influence of photocatalyst type, photocatalyst dosage (5–25 mg), solution pH (2–11), and dye's initial concentration (10-50 ppm) on the photocatalytic reduction of dyes in the visible light range were examined. Significant findingsThe performance of solar photocatalytic reduction of the PbS/ZIF-67 nanocomposite generally grew with the presence of visible light, and increment of photocatalyst loading, while decreased by higher amounts of dyes initial solution concentration. Kinetic results demonstrated that the pseudo 1st order model (simplified Langmuir-Hinshelwood equation) was the desirable method for describing the experimental data. Photocatalytic regeneration also indicated that the photo reduction efficiency stood at the higher amounts over 4 cycles, demonstrating the important regeneration ability of nanocomposite.

Preparation of biochar based on grapefruit peel and magnetite decorated with cadmium sulfide nanoparticles for photocatalytic degradation of chlorpyrifos

Agricultural pesticides are known as the most important causes of water pollution due to their high environmental stability and production of carcinogenic products. Chlorpyrifos is broadly utilized to control pests in agricultural, residential, and commercial applications. The release of chlorpyrifos into water and wastewater sources may affect human health because of its chronic toxicity to aquatic organisms. Therefore, its degradation seems necessary. The present study aimed to investigate the photocatalytic efficiency of biochar nanocomposite based on grapefruit skin modified with Fe3O4 and CdS nanoparticles (biochar/CdS-Fe3O4) in the degradation of chlorpyrifos pesticide as an agricultural contaminant. The synthesized nanocomposites were characterized using field emission scanning electron microscopy (FESEM) with energy dispersive X-Ray spectroscopy (EDS), X-ray diffraction (XRD), and transmission electron microscopy (TEM). The synthesized nanocomposite showed excellent photocatalytic performance due to the improved separation of electrons and holes produced by CdS and the inhibition of agglomeration of these nanostructures by combining them at the biochar surface. According to the results, 97% of chlorpyrifos was degraded by the prepared nanocomposite during the photocatalytic process. The photocatalytic activity of the synthesized nanocomposite was dependent on the parameters of time, pH, pesticide concentration, amount of used photocatalyst, which were optimized. The pseudo-first-order kinetic model derived from the Langmuir-Hinshelwood equation well describes the behavior of the experimental data in this study. It was also reused several times after washing to evaluate the stability of the synthesized photocatalyst. This study introduced a new type of photocatalyst for pesticide degradation.

Degradation of Carbamazepine from Aqueous Solutions via TiO2-Assisted Photo Catalyze.

Photocatalytic degradation of carbamazepine (CBZ) from spiked aqueous solutions, via a UV/TiO2 system, was investigated, and the optimum photocatalyst type (P25 Degussa) and dose (500 mg/L), as well as irradiation time (45 min), were established. The degradation process kinetics was studied, and a degradation rate constant of 3.14 × 10−5 M min−1 was calculated for CBZ, using the Langmuir–Hinshelwood equation. Experiments performed in the presence of scavengers showed that the main reactive species involved in the degradation process are holes and free hydroxyl radicals; superoxide radicals also play a role in CBZ degradation. Eight transformation products of CBZ were identified, and a possible degradation pathway, consisting of four routes, was proposed. Toxicity and genotoxicity tests were also performed for both untreated and treated CBZ solutions, proving that the use of a UV/TiO2 system represents a suitable treatment approach for aqueous systems with CBZ content.

CO2-gasification kinetics of biomass char with a red mud oxygen carrier for chemical looping combustion

Experiments and modelling of CO2-gasification of rice husk char which was derived from its pellet pyrolysis, were performed in a bed of red mud oxygen-carrier with respect to chemical looping combustion. Effects of oxygen carrier, temperature, CO2 concentration were evaluated and modeled. An experimentally-fitted function was used for expressing the char characteristics evolution. The red mud remarkably enhanced char gasification due to the fast consumption of CO. Thus, a simplified Langmuir-Hinshelwood equation by neglecting the influence of CO was applied for evaluating the intrinsic kinetics. A model coupling the kinetics of char gasification and mass transfers throughout and surrounding the whole char were established. A good agreement between modelling and experimental results was obtained. With the reaction progressing, the dynamic of concentration gradients suggested the mass transfer resistance within the char particle. The gradients increased until the carbon conversion was about 0.3, which was corresponding to the pore structure change.

Photocatalytic efficiency of titania nonylphenol ethoxylate composite thin films under solar irradiation

Photocatalytic efficiency of titania thin-films on ITO synthesized in the presence of nonylphenol-surfactants containing different numbers of ethoxylate-units was investigated under solar-irradiation. A colorless transparent titania-gel formed in the non-aqueous medium in the presence of nonylphenol-10-ethoxylates while milky white opaque gel was observed with nonylphenol-35-ethoxylates. They were coated on ITO plate by dipping method and calcined at 350, 500 and 700 °C. The XRD, IRRAS, EDS, SEM and AFM analyses revealed that different composite nanostructures are formed by calcinations of Ti-nonylphenol-35-ethoxylates at 350 and 500 °C. The photocatalytic-efficiencies of the composite films are better than the other titania nanostructures. Transparency and band-gap energy evaluated from transmittance measurements demonstrated that visible-light responsive Ti-nonylphenol-35-ethoxylates composites are more efficient catalysts than UV-absorbable Ti-nonylphenol-10-ethoxylates films. The photocatalytic degradation rate of the methylene-blue on the catalysts was calculated using the Langmuir-Hinshelwood equation and its modified form derived in this study by considering intensity changes in solar light. The dye degradation efficiency of the Ti-nonylphenol-ethoxylate films changes in the 58–74% range after 2 h of irradiation in 0.02 mM MB solution. The solution completely decolorized after 8 h of irradiation on the TiNP-35 catalysts calcined at 350 °C.

Degradation of organic contaminants in marine sediments by peroxymonosulfate over LaFeO3 nanoparticles supported on water caltrop shell-derived biochar and the associated microbial community responses

Sediment is an important final repository of persistent organic pollutants such as polycyclic aromatic hydrocarbons (PAHs). Herein, a novel catalyst of LaFeO3 nanoparticles supported on biochar was synthesized from water caltrop shell by chemical precipitation. The composite (LFBC) was used as peroxymonosulfate (PMS) activator to oxidize PAHs in real marine sediments. Systematic surface characterization confirmed the immobilization of well crystalline nano LaFeO3 particles onto the biochar surface. Under optimal conditions, i.e., [PMS] = 3 × 10-4 M, [LFBC] = 0.75 g/L, pH 6.0, and seawater, the total PAH degradation efficiency was 90%, while that of 2-, 3-, 4-, 5-, and 6-ring PAHs was 52%, 61%, 66%, 56%, and 29%, respectively, in 24 h. The Langmuir-Hinshelwood equation better predicted the PAHs degradation kinetics over LFBC by PMS. Interactions between surface oxygen species at LaFeO3 defective sites and the graphitized biochar network facilitated the PAHs degradation. Furthermore, changes in the bacterial community during the LFBC/PMS treatment were highlighted to assess the sustainable development of the sediment ecosystem. The LFBC/PMS process enhanced the biological richness and diversity of sediment eco-systems. The major phylum was Proteobacteria initially, while Hyphomonas was the genera after LFBC/PMS treatment of the sediment.

Preparation of ultra-thin TiO2 shell by peroxo titanium complex (PTC) solution-based green surface modification, and photocatalytic activity of homo-core/shell TiO2

Here, we report a discussion on the development of a new and sustainable green surface modification process to improve environmental pollution by modifying the surface and structural properties of nanostructured materials. Homo-core/shell TiO2 (HCST) was successfully synthesized through a peroxo titanium complex (PTC) solution-based surface modification process. The PTC solution is easily synthesized by the interfacial ion diffusion-redox reaction of Ti-metal and successfully forms an ultra-thin TiO2 shell (~2 nm) on the P-25 surface. The presence of these TiO2 shells not only causes high organic pollutant adsorption properties but also accelerates the photocatalytic activity along with the rich hydroxyl groups and oxygen vacancies present on the shell surface. The photocatalytic properties depend on the mixing ratio of the PTC solution and the heat treatment temperature and exhibited methylene blue (MB) removal efficiency of up to 99% or more and excellent recycling properties. Under optimal conditions, the rate constant value of HCST was calculated to be 17.14 × 10−3 min−1, about 2.7 times higher than P-25 through the Langmuir-Hinshelwood (L-H) equation.

UV-A light irradiated photocatalytic performance of hydrothermally obtained W doped BaZrO3 catalyst against the degradation of levofloxacin and tetracycline antibiotic

In this work, BaZrO3 semiconductor was synthesized hydrothermally and tungsten (W) was doped into the structure to enhance the photocatalytic activity by reducing the band gap energy of BaZrO3. BaZrO3/W was produced using different W ratios (5−15 wt%). Photocatalytic performance of levofloxacin (LV) and tetracycline (TC) degradation was inquired under UVA and visible light irradiation. BaZrO3/W/15 and BaZrO3/W/5 photocatalysts exhibited best degradation for LV (93.4 %) and TC (94.9 %), respectively. To investigate structure of the catalysts, XRD, SEM-EDX, and XPS analysis were examined. Characterization results proved the existence of W in BaZrO3 structure. The rate constant (kapp) was calculated by using Langmuir-Hinshelwood equation. The kapp values were achieved as 1.27*10−2 min-1 and 0.46*10−2 min-1 for LV, while 1.32*10−2 min-1 and 1.01*10-2 min-1 for TC under UVA and visible light, respectively. According to stability results, after fourth cycle LV degradation was found as 38.9 %, while TC degradation was obtained as 50.2 %.

Magnetically separable CoFe2O4/ZrO2 nanocomposite for the photocatalytic reduction of hexavalent chromium under visible light irradiation

In this study, CoFe2O4/ZrO2 nanocomposite was synthesized by hydrothermal method for photoreduction of hexavalent chromium. ZrO2 nanoparticles were modified by CoFe2O4 nanoparticles to increase the photocatalytic activity of the nanocomposite. The prepared nanocomposite was then characterized by Scanning electron microscopy (FESEM), Fourier transform infrared (FTIR) spectroscopy, X- ray diffraction (XRD), Dynamic light scattering (DLS),Vibrating sample magnetometer (VSM) and UV–vis diffuse reflectance spectroscopy (UV–vis DRS). In the second part of the research, the effect of pH (2–8), irradiation time, photocatalyst dosage (0.005–0.03 g) and chromium solution concentration (10–50 mg/L) on the photocatalytic reduction of hexavalent chromium under visible light were investigated. Increase in irridation time and photocatalyst dosage had a positive impact on photocatalytic reduction. Additionally, photocatalytic reduction of hexavalent chromium in alkalic environment was less than that of the acidic environment. A maximum photoreduction efficiency up to 83 % was obtained at optimum condition, i.e. pH = 2, 0.02 g photocatalyst, 10 ppm chromium solution. Finally, kinetic studies using pseudo-first order model (simplified Langmuir-Hinshelwood equation) suggested that the implemented model was suitable for describing the experimental data.

Determination of the Intrinsic Gasification Kinetics of a Bituminous Coal Including Product Gas Inhibition and Char Deactivation Under Entrained Flow Conditions

Abstract This work provides experimentally obtained data concerning the gasification of bituminous coal under entrained-flow conditions. The main focus lies on the determination of reaction kinetics with and without product gas inhibition as well as on thermal deactivation behavior. For this reason, experiments were carried out in a pressurized high-temperature entrained-flow reactor. The reactor is designed for temperatures of up to 1800 °C and pressures of up to 50 bar. In this study, char samples with different residence times at temperatures between 1200 °C and 1600 °C and a pressure of 10 bar were obtained. Pyrolysis experiments were performed in pure nitrogen, while an O/C ratio of one was selected for the gasification. In addition to ultimate, proximate, and structural analyses of the char samples, e.g., to calculate conversion according to the ash tracer method, intrinsic reaction kinetics of the pyrolysis chars with carbon dioxide and steam were determined in a high-pressure thermogravimetric analyzer. The influence of carbon monoxide inhibition on carbon dioxide gasification and of hydrogen on steam gasification was quantified using the Langmuir–Hinshelwood equation. Further, the deactivation behavior of the pyrolysis chars was analyzed by measuring their reactivities under constant reaction conditions and plotting them as a function of residence time. The presented results give an overview about factors like temperature, pressure, gas composition, and residence time affecting fuel conversion. Furthermore, constants describing the reaction behavior of the fuel were determined, which can be used for future simulation of gasification processes.

A simple way to prepare palladium nanoparticles decorated with cyclodextrins and ionic liquid. The effects of coating on the catalytic activity and colloidal stability

In this work, palladium nanoparticles (PdNps) were synthesized by reducing palladium chloride with sodium borohydride (NaBH4) aqueous solutions in presence of organic capping ligands such as β-cyclodextrin (βCD), an amphiphilic imidazole-based Ionic Liquid (C12mimBr) and an amphiphilic βCD derivative (βCDMOD14). The results demonstrated that the molecular organization of the capping agents has an important role in the stability of colloidal solution of PdNPs. In particular, the stability of PdNPs coated with βCDMOD14 ([email protected]βCDMOD14) can be controlled by changing the pH of the colloidal suspension. In addition, we propose that during the synthesis of PdNps and capped with C12mimBr ([email protected]12mimBr), the source of palladium is a coordination complex formed due to the presence of C12mimBr. Additionally, we studied the catalytic activity of [email protected]βCDMOD14 and [email protected]12mimBr using the reduction reaction of aromatic nitro compounds to aromatic amine in the presence of NaBH4, as a model in the remediation of aqueous phase. The kinetic data were modeled to the Langmuir–Hinshelwood equation that allows us to discriminate the affinity of 4-NP and NaBH4 towards modified surface of NPs in terms of their association constants (K4-NP, KBH4).

Parametric Study on Photocatalytic Dye Degradation under Visible Light in Flat Slurry Reactor with nano-ZnO Photocatalyst

A simple rectangular shape photoreactor of 10-L capacity was fabricated in glass plates. The performance of the reactor in the degradation of Orange M2R dye was evaluated under sunlight with ZnO as a photocatalyst. The Orange M2R dye was selected in the study as it is used for the fabric dying. Analytical reagent grade ZnO was used as photocatalyst as it displayed higher photocatalytic activity than synthesized ZnO. The degradation study of dyes was performed under sunlight. The pH of the dye solution, catalyst dose, and height of the dye solution in the reactor were identified as crucial experimental parameters affecting the dye degradation. The pseudo first-order decolourisation rate constant under optimized reaction conditions was evaluated by applying the Langmuir–Hinshelwood equation. Mineralization of the dye was accounted in terms of chemical oxygen demand. Furthermore, a flat slurry reactor-based process was applied for the degradation of dyes from the actual effluent and found effective.

Enhanced photocatalytic degradation of tetracycline using hydrothermally synthesized carbon fiber decorated BaTiO3

Barium titanate (BaTiO3) has been emerged as an efficient photocatalyst due to its optical and electromechanical properties. However, due to large band gap of BaTiO3, different materials are used to decrease band gap energy. In this study, carbon fiber (CF) was used to decrease band gap energy of BaTiO3 and the photocatalytic activity for the degradation of tetracycline was investigated under UV and visible light irradiation. BaTiO3/CF was synthesized by hydrothermal method for different CF ratios (5–15 wt %). BaTiO3/CF/5 catalyst showed the best degradation efficiency (96% under UV light) among the other samples. The photocatalysts were characterized by XRD, SEM-EDAX, FTIR analysis, etc. According to XRD analysis, high crystallinity was observed for both BaTiO3 and BaTiO3/CF. Besides, FTIR results also show the evidence of carbon fiber over the BaTiO3 structure. First-order reaction rate constant, kapp, was calculated using Langmuir-Hinshelwood equation. The kapp values were found as 1.63*10−2 min−1 under UV-A light and 1.46*10−2 min−1 visible light irradiation for BaTiO3/CF/5. According to stability tests, after the first cycle tetracycline degradation was found as 96%, while it was 77% after fifth cycle.