Effect Of Catalyst Concentration Research Articles

Ultrasound-Assisted Photocatalytic Degradation of Azo Dyes under Visible Light Irradiation Using Polythiophene-Decorated CoFe2O4 Nanohybrids

The present work reports the synthesis of cobalt ferrite and its nanohybrids with polythiophene (PTh) in the weight ratios of 10% and 20%. The ferrite and its nanohybrids were characterized using thermogravimetric analysis (TGA), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy coupled with elemental mapping (Fe-SEM) to confirm the morphology as well as the structure of the synthesized nanohybrids. The nanohybrids were tested for their photocatalytic activity upon modification of PTh against Alizarin Yellow (AY), Congo Red (CR) and Brilliant Blue (BB). Almost 100% degradation was achieved in 30 min using 50 mg of the photocatalyst. The effect of catalyst concentration and dye concentration was also investigated to explore optimum concentration of the photocatalyst required for rapid degradation of the dye. The generation of radicals responsible for degradation was analyzed by radical scavenging experiments and a probable mechanism of degradation was proposed.

In situ epoxidation of oleic acid with applied natural zeolite as a catalyst

AbstractIn recent years, there has been a growing demand for environmentally friendly epoxides made from vegetable oils. Therefore, the use of materials from renewable resources, was implemented in this study with natural zeolite as a catalyst being chosen over synthetic zeolite because synthetic zeolite mostly consists of strong corrosive materials. The aims of this research to determine the effect of catalyst concentration on the relative conversion of oxirane (RCO). RCO was the highest at 30 min of the reaction for sunflower oil, being 72% at 80°C using a 0.25 g concentration of catalyst. Meanwhile, for palm oil, the highest RCO was only 52% at 80°C. Lastly, MATLAB software was used to develop a mathematical model for determination rate constant. In this model, the Runge–Kutta method of the fourth order was combined with genetic algorithm optimization to for development of kinetic model that best fitted with the experimental data.

Green synthesis of metal oxides (CaO-K2O) catalyst using golden apple snail shell and cultivated banana peel for production of biofuel from non-edible Jatropha Curcas oil (JCO) via a central composite design (CCD)

The use of biomass as a renewable, sustainable, and eco-friendly energy source is now widely recognized as a potential solution for a variety of environmental problems. To develop biodiesel production, cost-effective feedstocks such as agricultural waste, food waste, and non-edible/waste cooking oil were utilized. A heterogeneous solid base catalyst was synthesized by calcining a mixture of waste golden apple snail shell (Pomacea canaliculata) and cultivated (Musa sapientum) banana peel. In transesterification process, potassium oxide (K2O) derived from banana peel is used as a cocatalyst to improve the catalytic activity of calcium oxide (CaO) catalyst derived from waste shell. The innovative CaO-K2O catalyst was investigated by X-ray diffraction (XRD), X-ray fluorescence (XRF) and the Brunauer-Emmett-Teller (BET) technique. The morphology and elemental composition of calcium (Ca), potassium (K), and oxygen (O) in the catalyst were validated by field emission-scanning electron microscopy (FE-SEM) and energy dispersive X-ray spectroscopy (EDX). The CaO catalyst exhibited a BET surface area of 10.88 m2/g, which was enhanced to 14.62 m2/g upon combination with K2O. The Hammett indicator of CaO catalyst fell between 7.2 < H_< 9.8. However, the CaO-K2O catalyst exhibited a higher value of 15.0 < H_< 18.4, which could be attributed to the phase transition from CaO to CaO-K2O. To investigate the effects of catalyst concentration, ethanol/oil molar ratio, and transesterification time on the yield of fatty acid ethyl ester (FAEE). The optimal conditions for FAEE synthesis were determined using a central composite design (CCD) approach with response surface methodology (RSM). The regression equation obtained for the CCD model has a determination coefficient (R2) of 0.9921, indicating that this model is well-fitted. At 3.69 wt% catalyst concentration, 19.48:1 ethanol/oil molar ratio, and 1.80 h transesterification time, the highest FAEE yield from Jatropha Curcas oil (JCO) of 97.06 % was obtained. The novel catalyst has a strong yield and can be utilized for up to 6 cycles. It was found that the corresponding yield was 90 % when employing the same process parameters, demonstrating the high reusability of this catalyst. The biodiesel produced from non-edible JCO meets the criteria for standard biodiesel (ASTM D-6751 and EN 14214). The CaO-K2O catalyst is inexpensive, easy to make, biodegradable, recyclable, and environmentally friendly because it is derived from a biological residue. Because of these characteristics, it may be an appropriate candidate for the role of “green catalyst” in sustainable energy production.

One‐step in‐situ growth of CNTs on oxidized carbon fiber: Effects of catalyst concentration and growth time on mechanical properties of carbon fiber

AbstractChemical vapor deposition (CVD) method was performed to grow carbon nanotubes (CNTs) on oxidized carbon fiber (CF). First, CF was oxidized by a simple and gentle way to increase the number of active groups and the optimal treatment time was determined. Then, effects of catalyst concentration and growth time on morphologies and loading amount of CNTs, the properties of CF/CNTs reinforcements, and the interlayer properties of CF/CNTs composites were explored. When the catalyst concentration and growth time were controlled at a reasonable level, CNTs can be uniformly grown on the CF surface. The interlaminar shear strength (ILSS) was characterized and the fracture surfaces of CF/CNTs composites were observed. The results demonstrated that when the catalyst precursor was kept at 0.05 mol/L and the growth time was controlled at 10 min, CNTs had the best strength effect and the ILSS increased by 30.25% compared to that of composites without CNTs. The fracture surface showed that CNTs can penetrate the matrix at the interface and enhance the interface through mechanical interlocking effect. The CNTs‐induced interphase allows the stress inside the composites to propagate continuously between resin and fibers, thereby heightening the load carrying capacity.Highlights A simple and gentle way was performed to activate CF without strength reduction. The influence mechanism of various parameters was revealed in detail. The mechanism of CNTs enhancing the interface was revealed.

Experimental, predictive and RSM studies of H2 production using Ag-La-CaTiO3 for water-splitting under visible light

Ag-La-CaTiO3 was used in place of sacrificial agents to assess the influence of operational factors on hydrogen generation in a photocatalytic water splitting system. After being synthesized, the physicochemical features of this substance were accurately described. Several characterization techniques including UV–Vis spectroscopy, FTIR, XRD, XPS, EDX, SEM, TGA, DRS and BET were applied to study the prepared Ag-La-CaTiO3 photocatalyst. Ag-La-CaTiO3 shows a band in the visible wavelength between 400 and 800 nm at < 560 nm compared to the main CaTiO3 band at 350 nm. Ag 4d5s electrons transition to the conduction band (CB), which is responsible for the absorption band at ~ 560 nm (> 2.21 eV). The effects of catalyst concentration, light intensity, and beginning solution pH on the H2 generation rate may all be evaluated simultaneously using experimental design procedures. Up to a maximum threshold, where a drop in the rate of gas evolution occurs, it was confirmed that the increase in catalyst dose positively affects system productivity. The initial solution pH plays a crucial role in H2 production, and pH = 4 and 10 are the optimum pH with a higher yield of H2 production. The highest total H2 production rate, 6246.09 μmol, was obtained using a catalyst concentration of 700 mg and solution pH equal to 10 under 1200 W Vis lamp for 3 h. For prediction and optimization, a D-Optimal design was applied and the optimal results were pH 4, the catalyst dose of 645.578 mg and 1200 W with H2 production of 6031.11 μmol.

The effect of various factors on the yield of 2,3,3–triiode propene–2–ol–1

A triode derivative of propargyl alcohol has been synthesized, and the effects of catalyst concentration, time and temperature on the synthesis process have been studied. Various concentrations of alkalis (5,0–30,0 mass. %) have been used as catalysts. It has been found that 2,3,3–triode propene–2–ol–1 has a higher yield when the concentration of the catalyst NaOH is 15%. The effect of time duration (1–5 hours) on product productivity has also been studied. Product yield has been found to be high for 3 hours. In addition, the effect of temperature on the product’s productivity has also been studied at intervals of (10–60°C). It has been found that the yield of 2,3,3–triiodpropen–2–ol–1 was high in 3 hours at 20°C. The structure of the synthesized substance was studied and confirmed by the methods of IR– and NMR–spectroscopic analysis.

The experimental study on the air oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid with Co–Mn–Br system

Abstract 2,5-Furandicarboxylic acid (FDCA), an eco-friendly biomass resource capable of replacing petroleum-based fuels, is gaining increasing popularity. In this article, 2,5-FDCA was prepared by liquid-phase oxidation of the sustainable precursor 5-hydroxymethylfurfural using the Co–Mn–Br catalyst system. The effects of catalyst concentration, catalyst ratio, reaction temperature, reaction time, reaction pressure, and solvent ratio on the reaction of FDCA were investigated. The products are subjected to qualitative and quantitative analyses using high-performance liquid chromatography, infrared spectroscopy, and hydrogen nuclear magnetic spectroscopy. Moreover, considering the loss of catalytic liquid, the suitable reaction conditions were determined as follows: n(Co)/n(Mn)/n(Br) = 1/0.04/0.5, n(HMF)/n(HAC) = 0.05, reaction temperature of 170°C, reaction pressure of 2 MPa, reaction time 40 min, and airflow rate 1.0 L·min−1. Under these conditions, the yield of the product is 86.01%, the purity is 97.53%, and the loss of the catalytic liquid is about 5.63%, which is at an ideal level and provides a good basis for the recovery of the subsequent catalytic liquid and multiple cycle reactions. Through the optimization of the existing process, the use of noble metal catalysts has been reduced, and the recycling of catalytic liquid has also reduced the consumption of catalysts. This advancement marks a significant stride toward sustainable development in the green chemical industry.

Controlled crushing device-intensified direct biodiesel production of Black Soldier Fly larvae

Insect larvae contain sufficient oil comparable with oleaginous biomass, and hence have potency as alternative biodiesel resources. The direct transesterification of Black Soldier Fly (BSF) larvae have conducted using a controllable crushing device (CCD) and a homogeneous base as a catalyst. The effect of catalyst concentration (wt.%), ratio BSF larvae to methanol (wt./v), reaction time (min) and rotational speed (rpm) on biodiesel conversion was determined. The maximum conversion of 93.8% was achieved at room temperature after 20 min of reaction time and ratio larvae to methanol of 1:2 (wt./v), catalyst concentration of 7 wt% and rotational speed of 3000 rpm. In addition, the green metrics calculation showed that this method produces less waste and uses less solvent. Some of the BSF-biodiesel properties meet the biodiesel standard. The CCD-intensified the DT of BSF larvae is a promising alternative for green and energy-saved biodiesel production.

Optimisation of lignin liquefaction with polyethylene glycol/ glycerol through response surface methodology modelling

In order to diminish the dependence on oil lignin, which is the most abundant biopolymer of phenolic origin on Earth and can be utilised in different industrial endeavours, such as, the production of polyurethanes. In this study, hardwood (Eucalyptus globulus) and softwood (Pinus radiata) organosolv lignins were employed to produce bio-polyols trough microwave-assisted liquefaction. The resulting bio-polyols possessed specific properties to be employed in the synthesis of rigid and elastic polyurethanes. The values of the reaction parameter were optimized using response surface methodology to determine the most effective conditions for producing bio-polyols from both types of lignins for the purpose of rigid and elastic polyurethane formulation. The effect of catalyst concentration (%wt.), temperature (ºC) and Polyethylene glycol/Glycerol weight ratio on the molecular weight (Mw) and hydroxyl number (IOH) of bio-polyols was evaluated. The optimum reaction conditions of bio-polyols production for rigid polyurethanes were virtually equal for the two lignins, 159–161 ºC, Polyethylene glycol/Glycerol ratio of 3 without catalyst. On the contrary, the bio-polyols for elastic polyurethanes required different reaction parameters depending on the lignin used. For hardwood lignin the optimised conditions were 180 ºC, 7.57 (Polyethylene glycol/Glycerol ratio) and 5.00% of catalyst while for softwood lignin were 160 ºC, 7.34 (Polyethylene glycol/Glycerol) and 3.85% of catalyst. Additionally, the bio-polyols obtained at optimised conditions were fully characterised and acid number, polydispersity index, functionality and the rheological behaviour was studied.

Enhanced production of liquid fuel via catalytic cracking of used sunflower oil catalyzed by Praseodymium supported alumina

The production of alternative fuel from the cracking process (CP) of waste cooking oil (WCO) is considered an efficient way to displace the used fossil fuel. The catalytic cracking process was evaluated using praseodymium oxide-supported alumina. The prepared catalysts were characterized by advanced techniques such as XRD, BET, IR, TGA, SEM, and TEM. Different parameters such as praseodymium loading, effect of temperature and effect of catalyst concentration were studied and investigated. The data revealed that the maximum conversion was found to be ∼ 92 % at Pr weight loading of 10 %, temperature of 350 °C, and catalyst weight as a percent of WCO weight is 0.6 %. The routine analysis established that the specifications of the resulting fuel indicate that it conforms to international specifications of fossil fuel. The gas chromatography proved that the percent of hydrocarbons from C5-C16 represents 41.5 % of the liquid biofuel.

Biowaste carbon supported manganese nanoparticles as an active catalyst for the selective hydrogenation of bio-based aldehydes

Hydrogenation of aldehydes with heterogeneous manganese catalysts is an appealing approach for producing alcohols. In this paper, we report a novel and robust MnO/PN-800 catalyst for the hydrogenation of versatile biomass-derived platform molecules in the presence of molecular hydrogen as a reductant. The effect of catalyst concentration, the operating hydrogen pressure, and the reaction temperature on the catalyst activity was investigated in detail. Under the mild reaction conditions, the full conversion of furfuraldehyde, 5-Methyl-2-furaldehyde, and 5-hydroxymethyl-2-furaldehyde (5-HMF) to their corresponding alcohols was achieved without any by-product formation. Additionally, other aromatic aldehydes bearing fluoro, chloro, and nitro moieties were also tolerated. The fresh and spent MnO/PN-800 catalyst was thoroughly characterized using XPS, powder-XRD, HR-TEM, N2 adsorption-desorption, and Raman spectroscopy. Noteworthy, the MnO/PN-800 catalyst can be recovered by centrifugation and then reused directly in the subsequent hydrogenation reactions. Importantly the synthetic utility of this protocol up to ∼5 g-scale is realized. Finally, our novel MnO/PN-800 nanocatalyst was successfully employed for the direct synthesis of furfuryl alcohol in high yields from raw sugarcane bagasse. We believe that these findings will help to advance the manganese-catalyzed hydrogenation reactions.

Morphological studies and photocatalytic degradation of methylene blue by zinc sulfide nanoparticles

"We report the preparation, morphological and photocatalytic studies of zinc sulfide nanoparticles from zinc(II) dithiocarbamate precursors. Powder X-ray diffraction patterns were index to the wurtzite crystalline phase of zinc sulfide while transmission electron microscopy micrographs revealed spherically shaped particles with sizes in the range 2.8 to 5.2 nm. The ZnS nanoparticles were used as photocatalysts for the degradation of methylene blue with degradation efficiency of 71.41% for ZnS1 and 85.95% for ZnS2 nanoparticles at pH 9.43. The effect of catalyst concentration, pH, radical scavengers, and hole (h+ ) scavengers on the photodegradation of methylene blue dye were evaluated."

Aryl sulfonic acid catalysts: Effect of pendant group structure on activity in hydrolysis of polyethylene terephthalate

AbstractA series of aryl sulfonic acids were tested as catalysts for acid hydrolysis occurring at the surface of poly(ethylene) terephthalate (PET) particles. Specifically, p‐toluenesulfonic acid monohydrate (PTSA), 2‐naphthalenesulfonic acid (2‐NSA), and 1,5‐naphthalenedisulfonic acid tetrahydrate (1,5‐NDSA) were chosen to provide sulfonic acid active groups and varying hydrophobic functionality. The effect of catalyst concentration and reaction temperature on PET hydrolysis rate was studied. The aryl sulfonic acid catalysts exhibited much higher rates of PET hydrolysis than the mineral acid, H2SO4. At 150°C and 4 M catalyst, the time required to achieve more than 90% TPA yield was 3, 3, and 8 h, and 18 h for (PTSA), (2‐NSA), (1,5‐NDSA), and H2SO4, respectively. Ethyl acetate hydrolysis was performed as a model reaction to probe the activity of the catalysts in homogenous reactions to compare with the heterogenous hydrolysis reaction occurring at the PET surface. The higher catalytic activities for PET hydrolysis of the PTSA, 2‐NSA, and 1,5‐NDSA than H2SO4 was attributed to improved wetting by the reaction media and affinity of the aryl sulfonic acid catalysts for the PET surface.

Catalytic pyrolysis kinetic behaviour of glass fibre-reinforced epoxy resin composites over ZSM-5 zeolite catalyst

The catalytic pyrolysis process is an environmentally friendly technology used to decompose the organic waste into chemical and volatile compounds with high abundance and quality. In the present research, the catalytic pyrolysis treatment was used to decompose the organic fraction of end-of-life glass fibre-reinforced epoxy resin composites (GFRP) over ZSM-5 zeolite catalyst into energy products, thus liberating a fiberglass fraction. The pyrolysis process was performed using thermogravimetry (TGA) with different ZSM-5 to GFRP ratios (w/w; 0.5, 1, 2, 5 wt%) and the generated volatile compounds at ratio were observed using TG-FTIR and GC–MS system. Also, the effect of catalyst concentration on pyrolysis kinetics of GFRP and its activation energies (Ea) was studied using (KAS, FWO, and Friedman) linear isoconversional, (Vyazovkin and Cai) nonlinear isoconversional, the distributed activation energy (DAEM), and the independent parallel reactions (IPR) models. The characteristics of the TGA curves and FTIR spectra were not significantly changed by addition of the catalyst, where the average weight loss was in the ranges 60–64 wt% and aromatic benzene and CO2 the main functional groups in FTIR results. Meanwhile, GC–MS analysis showed that catalyst and heating rates play an important role in the yield of the recovered phenol compound and the highest yield (66%) was obtained at 5 °C/min and ZSM-5 to GFRP ratio = 2 (with increasing 43% compared with virgin GFRP). Based on that, the pyrolysis process supported by ZSM-5 zeolite can be used to recover phenol from GFRP.

Photocatalytic degradation of phenylene diamine using TiO2-rGO under UV radiation

In this study, phenylene diamine (an organic pollutant) was photo catalytically degraded by using TiO2-rGO nanoparticles in the UV radiation. Graphite powder was used to produce the rGO using modified hummers' method. Titanium isopropoxide was used to prepare TiO2 using hydrolysis. Hydrothermal method was used to produce TiO2-rGO nanoparticles. XRD and SEM were done to characterize the catalyst. The experiments under UV-light were conducted in the photo reactor to determine the percentage of degradation. The change in concentration vs time was observed with the change in absorbance value in the UV spectroscopy. The effect of catalyst concentration, phenylene diamine concentration and pH was also studied. Kinetics study was carried out and the degradation mechanism of phenylene diamine was discussed.

Bio-Synthesized Silver Nanoparticles For Effective Photo- catalytic Degradation of Congo Red Dye in Aqueous Solutions: Optimization Studies Using Response Surface Methodology

The focus of the project is the new, low cost and simple nature mediated formation of silver nanoparticles (Ag-NPs) using leaf extract of Anisomeles malabarica. The shape and size, structure, element composition, and functional groups of green synthetic Ag-NPs have been studied by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray (EDX), and Fourier Transform Infrared (FTIR), respectively. BET analysis has been used to calculate the specific surface area of the particles, and GC- MS analysis has been used to confirm the presence of biologically active components in leaf extracts. Based on the observed results, the possible formation mechanism of AgNPs has been given. The obtained Ag-NPs have the physical property of spherical shape and nature of crystallinity, with an average size of about 63 nm. Ag- NPs have shown promising potential in the removal of organic pollutants Congo red (CR) dyes. Dye removal as a function of contact time has also been carefully studied. The experimental value of the dye degradation study was fitted with a first-order linear kinetic model to understand the reaction rate. The response surface methodology is used to study the effect of catalyst concentration, dye concentration, and irradiation time on the percentage of dye degradation and process optimization based on Box-Behnken Design Methodology (RSM). The result of the RSM model value R2 = 99.97 % gives a satisfactory correlation between the experimental and predicted value for dye removal. After 15 minutes of reaction time, maximum degradation of 99.97 % was achieved under optimal conditions (1 mM dye concentration, 1 mg photocatalyst concentration). Therefore, we were able to produce the photocatalyst using Anisomeles malabarica leaf extract that can degrade azo dyes.

Organic acid-assisted catalytic wet torrefaction of oil palm trunks (OPT)

Oil palm trunks (OPT) are attractive bio-fuel sources given their abundant availability. Nonetheless, the inherent properties of these biomass can lead to their inefficient use as bio-fuel directly. This work utilizes four organic acids (i.e., acetic, formic, levulinic, and citric acid) as catalyst in wet torrefaction to enhance the fuel properties of OPT hydrochar. In this study, the effects of different catalysts, catalyst concentrations, and residence times on the fuel properties of OPT hydrochar are analyzed. To study the effect of residence time, 0.2M of acid concentration was used for all four acids at 220 °C for 3 hr and 24 hr. Meanwhile, study on the effect of catalyst concentration was performed at 220 °C for 24 hr at 0.2M and 1.0M for all four acids. Increasing the residence time decreased the solid yield of OPT hydrochar treated in deionized water, acetic, formic, and levulinic acid, while wet torrefaction in citric acid results in close solid yield value in both residence time. The energy yield was observed to decrease in all liquid medium with increasing residence time except for formic acid and citric acid. On the other hand, increasing the acid concentration increased the OPT hydrochar solid yield in all acids except formic acid and the highest energy yield of 77.08% was obtained from wet torrefaction in 1.0M of citric acid at 220 °C for 24 hr. In summary, citric acid is an environmentally friendly acid to be used as catalyst to enhance the fuel properties of OPT hydrochar. Further study on the reaction mechanisms that governs such fuel properties enhancement with citric acid is warranted.

Thermal aging and catalyst concentration effects on thermo-dynamical and mechanical properties of a polyester fiberglass composite

This work deals with the characterization by physicochemical and mechanical analysis performed on composite polyester fiberglass plates molded by contact and aged in thermo-stated ovens to simulate their deleterious environment of use. The DSC analysis revealed that the catalyst concentration affected the thermal behavior of the composite. Indeed, the addition of a higher catalyst concentration slightly lowered the glass transition temperature. From a mechanical point of view, it was observed that the catalyst addition made the material stiffer. The properties at fracture were also affected by the catalyst concentration and varied irregularly with aging.

Solar-light-driven photocatalysis by Sb2S3/carbon based composites towards degradation of noxious organic pollutants

Heterojunction photocatalysts are quite appealing for the effective removal of pollutants. Herein, we compare the photocatalytic dye degradation of Rhodamine-B (RhB) using pristine Sb2S3 nanoparticles (Sb2S3-NPs), Sb2S3-NPs anchored onto reduced graphene oxide (Sb2S3/rGO), and Sb2S3-NPs coated with porous carbon spheres (Sb2S3@PCS) as heterojunction photocatalysts. The successful fabrication of Sb2S3/C based heterogeneous photocatalysts was confirmed by XRD, FTIR, and Raman spectroscopy. The morphological studies revealed the formation of ~150–500 nm Sb2S3 nanoparticles wrapped with rGO sheets or encapsulated within ~65 nm thick porous carbon spheres. BET surface area analyses disclose that incorporating rGO and PCS improves the sp. surface area and favorable surface properties for effective RhB degradation. The UV–Vis DRS and PL showed that the heterojunction composites had narrow bandgap (~1.6–1.8 eV) and a suppressed recombination rate of photo-generated charge carriers exhibiting excellent photocatalytic activity compared to Sb2S3-NPs. Sb2S3/rGO and Sb2S3@PCS demonstrated RhB degradation-efficiency of ~89% (rate constant~ 0.013 min−1) and 77.65% (0.0091 min−1) after 150 min sunlight irradiation. The effects of catalyst concentration and pH (correlated with pHpzc) on the photodegradation were also examined. The enhanced photocatalytic performance of heterojunction photocatalysts could be ascribed to e−-excitation from the valence to conduction band, and facile electron mediator of π-conjugated porous carbon for Sb2S3/rGO and Sb2S3@PCS, respectively. The efficient photodegradation of colorless thiamethoxam pollutant confirmed indirect photocatalysis. The Sb2S3/rGO composite exhibited ~64% efficiency (rate constant~0.0056 min−1) whereas the Sb2S3@PCS maintained ~62% efficiency (rate constant~0.0064 min−1). Overall, the present study shows that Sb2S3/C-based heterogeneous photocatalysts are promising for wastewater treatment.

Construction of Z-scheme CuFe2O4/MnO2 photocatalyst and activating peroxymonosulfate for phenol degradation: Synergistic effect, degradation pathways, and mechanism

Photocatalysis coupled with sulfate radical-based advanced oxidation process (SR-AOPs) is an efficient strategy to enhance the degradation efficiency of organic pollution. Herein, a Z-scheme CuFe2O4/MnO2 composite catalyst was successfully fabricated by the hydrothermal method. A series of characterizations demonstrated that the higher CuFe2O4 particle dispersion and larger BET surface area of CuFe2O4/MnO2 catalyst contributed to a high catalytic activity toward the phenol removal compared with pure CuFe2O4. The effects of catalyst concentration, pH, and peroxymonosulfate (PMS) concentration were studied according to the Box-Behnken Design (BBD) method. The results indicated that 100 mg/L 100 mL phenol could be degraded completely at 0.5 g/L CuFe2O4/MnO2 catalyst, pH = 4.8 and 0.5 mM PMS within 30 min. Moreover, the excellent reusability and stability of CuFe2O4/MnO2 were indicated by the results of recycling degradation and ion leaching test. The free radical quenching experiments and electron spin resonance (ESR) confirmed that h+, SO4•-, and •OH were the main reaction species for phenol oxidation. Based on the results of gas chromatography-mass spectrometry (GC-MS) and ion chromatography, the degradation pathway of phenol was proposed, and the toxicity of phenol degradation intermediates was evaluated. This work may provide new insights into the design of heterojunction photocatalysts for PMS activation to remove organic pollutants.