Eriochrome Black T Research Articles

Synthesis, Characterization, Photocatalytic and Antimicrobial Activities of Copper Doped Silver and Nickel Oxide Nanoparticles

ABSTRACT: The copper-doped silver and nickel oxide nanoparticles were prepared by the co-precipitation method in which the silver oxide (Ag2O) and nickel oxide (NiO) nanoparticles are doped with copper in 4:1 in the presence of sodium dodecyl sulfate (SDS), a surfactant. Then various analytical studies were carried out by using X-ray diffraction (XRD) and Diffuse reflectance spectroscopy (DRS). The XRD analysis revealed the crystalline structure and the size of nanoparticles was determined by using Scherrer’s formula. The XRD data showed the effect of doping on crystallinity and size. It was found that the size of nanoparticles was reduced without any change in crystallinity after doping. DRS results showed that when silver oxide and nickel oxide nanoparticles were doped with copper oxide nanoparticles, the energy band gap was shifted to a lesser value, i.e., from 1.50 to 1.17 eV for Ag2O and from 2.29 to 2.08 eV for NiO, respectively. The photocatalytic degradation of methylene blue (MB) and eriochrome black-T (EBT) by nanoparticles was monitored by UV-Vis spectroscopy. The antimicrobial activity of the synthesized nanoparticles was checked by using well diffusion assay and it was found that doped nanoparticles were more active than the undoped ones.

Electrochemical and spectroscopic characterization of a new polymer based on eriochrome black T doped by carbon nanotubes

An electropolymerized film of new eriochrome black T (EBT) doped with carbon nanotubes (CNTs) has been prepared on the surface of indium tin oxide (ITO) in a solution of acetonitrile containing lithium perchlorate (LiClO4) as supporting electrolyte by cyclic voltammetry (CV). The distribution of CNTs in the poly eriochrome black T (PEBT) matrix was studied through scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy. Their chemistry and electrical properties were determined by CV and electrochemical impedance spectroscopy (EIS). The optical characterization of the composites was made by UV–Vis absorption. The results showed that CNTs nanoparticles were dispersed and co-deposited into the PEBT matrix; the voltammogram of EBT before and after doping with the semiconductor of CNTs present a large difference in the form of recorded cyclic voltammograms. It is noticed that the shape (intensity, potential and number of redox couple) of the cyclic voltamperogram varies with the addition of CNTs; the appearance of new peaks of oxidation and reduction suggests the formation of a new composite material. This confirmed that there is a reaction which develops between the EBT, CNTs and LiClO4. The best distinction of the peaks was obtained during the addition of 0.2 mg of CNTs, leading to increase the conductivity of the PEBT film that forms on the ITO electrode. The images of SEM confirm the presence of CNTs in the composite, which consequently modifies significantly the morphology of the film. The CV study showed redox couples characteristic of poly EBT at 0.6 and 0.5 V. The EIS measurements show that the resistance of the PEBT films decreases with increasing of CNTs amounts. This demonstrates that the inclusion of the CNTs enhance the electrical properties of the polymer. Thus, these composite films can be used in various fields. The optical bandgap decreased generally with increase in content of CNTs compared with PEBT only. This is explained by the introduction of the donor levels in the bandgap of PEBT by the CNTs, this decrease in gap energy is explained by the Burstein–Moss effect.

Adsorption of Eriochrome black-T from aqueous environment by raw Montmorillonite

ABSTRACT The present study aimed to investigate the removal of the azo dye, Eriochrome black-T (EBT) from the synthesised effluents using the Montmorillonite (MM) raw clay. MM is a soft phyllosilicate group of minerals and has been used as a low-cost adsorbent for the removal of pollutants from the environment. In this regard, the effect of several factors, such as contact time, pH, adsorbent dose, initial dye concentration, solution ion strength, and temperature in the batch system was assessed. Fourier transformed infrared (FTIR) spectroscopy and X-ray diffractometer (XRD) techniques were also employed to examine the MM. Adsorption capacity of EBT in equilibrium time equal to 20 min was attained 57.88 mg/g. Removal of EBT by the MM illustrated that the data had a good fit with the models of pseudo-second-order and Freundlich isotherm. The contact time and pH were also optimised at 20 min and pH = 3, respectively. The maximum adsorption capacity (72.71 mg/g) was obtained for pH value of 3. Based on the value of RL in this study (RL = 0.70), the adsorption process of EBT removal using MM was favourable. The results from this study confirmed the effectiveness of MM as an inexpensive and eco-friendly option for the adsorption and removal of EBT from polluted water.

Mesoporous amine functionalized SiO2 supported Cu nanocatalyst and a kinetic-mechanistic degradation study of azo dyes

The preparation of stable copper nanoparticles (CuNPs) has remained a challenge for colloid chemists. In this investigation, mesoporous amine functionalized silica (NH2-SiO2) particles have been used as platform to host copper nanoparticles (CuNPs) for preventing their agglomeration. Mesoporous NH2-SiO2 particles are first prepared in one pot by diethyl amine (DEA) catalyzed hydrolysis and condensation of tetraethyl orthosilicate (TEOS) precursor in presence of hexamethylene diamine (HMDA) and cetyltrimethylammonium bromide (CTAB). In the second step, sequential adsorption and chemical reduction of Cu ions are carried out to obtain NH2-SiO2/Cu catalyst nanocomposites. The morphology and structural composition of NH2-SiO2/Cu catalyst nanocomposite particles confirmed the anchoring of evenly distributed ~ 28 nm sized Cu particles. The catalytic activity of nanocomposite particles for reductive degradation of Congo red (CR) and Eriochrome Black-T (EBT) showed maximum degradation at pH values of 7 and 4, respectively. The degradation efficiency increased with the increase in catalyst dose and a maximum degradation of ~ 92% is achieved for CR when 2 mg of catalyst nanocomposite particles is used. Comparatively, the degradation percent for EBT is low (~ 83%). Degradation kinetics of CR preferably followed a pseudo-first-order rate model, but, for EBT degradation hardly any particular kinetic rate model could be preferentially ascertained. The improved stability and increased surface-to-volume ratio of anchored CuNPs enhanced the degradation efficiency of catalyst nanocomposite particles.

Study of UiO-66 and UiO-66 Modulated with Acetic Acid as the Adsorbent for Eriochrome Black T Dye

UiO-66, as one of the metal-organic framework (MOF) compounds, has been used to treat some anionic and cationic dye waste. In order to determine the adsorption selectivity decisively, the synthesis of UiO-66 and UiO-66 modulated with acetic acid had been carried out, along with their adsorption tests for Eriochrome Black T (EBT) dye solution. The synthesis was performed by utilizing a solvothermal method with the reaction mixtures of zirconium (IV) chloride (ZrCl4) and terephthalic acid (H2BDC) as a ligand heated at 120 oC for 24 hours. Both UiO-66 (without acetic acid) and acetic acid modulated UiO-66 were obtained as a white powder. Acetic acid as a modulator was added and being investigated for the adsorption capability compared to the normal UiO-66. This study showed that normal UiO-66 exhibited better adsorption than acetic acid modulated UiO-66 with a mmol ratio of acetic acid:ligand varied from 50:1, 100:1, and 150:1. Acetic acid modulated UiO-66 with a mmol ratio of 50 exhibited the best crystallinity as observed by using x-ray diffraction. It can be concluded that the adsorption of EBT using normal and acetic acid modulated UiO-66 obeyed the pseudo-second-order reaction rate law as well as the Langmuir adsorption isotherm pattern.

Improvement of Laccase Activity Via Covalent Immobilization over Mesoporous Silica Coated Magnetic Multiwalled Carbon Nanotubes for the Discoloration of Synthetic Dyes.

Due to its environmental friendliness and biodegradable ability, the enzymatic decolorization of azo dyes is the best option. However, the free enzyme suffers from various limitations, including poor stability, no repeatable use, and a high expense, which is the key drawback for its practical use. In this analysis, the laccase enzyme was immobilized in mesoporous silica coated magnetic multiwalled carbon nanotubes (Fe3O4-MWCNTs@SiO2) by a glutaraldehyde cross-linker to create an easily separable and stable enzyme. Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX) were used to characterize the as-synthesized Fe3O4-MWCNTs@SiO2. Laccase immobilized in Fe3O4-MWCNTs@SiO2 showed a good improvement in temperature, pH, and storage stability. Moreover, the operational stability of the biocatalyst was improved, retaining 87% of its original activity even after 10 cycles of 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) oxidation. The biocatalysts were applied for the decolorization of selected azo dyes without a mediator, and up to 99% of Eriochrome Black T (EBT), 98% of Acid Red 88 (AR 88), and 66% of Reactive Black 5 (RB5) were decolorized. Based on these properties, the biocatalysts can be potentially utilized in various environmental and industrial applications.

Photocatalytic degradation of Eriochrome black-T and Evan’s blue dyes under the visible light using PVA capped and uncapped Ag doped ZnS nanoparticles

Photocatalytic degradation of Eriochrome black-T and Evan’s blue dyes under the visible light using PVA capped and uncapped Ag doped ZnS nanoparticles

Effect of molarity on Structural, Morphological, optical and the photocatalytic property of (Cu1-X-Cox)-TiO2 nanoparticles synthesized via hydrothermal method

Copper and cobalt co-doped TiO2 nanoparticles (NPs) [(Cu1-x-Cox)-TiO2 for x = 0.1 M and 0.9 M] have been synthesized through the hydrothermal method in the current investigation. X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM) and UV–vis spectrophotometer have characterized the structural, optical, morphological, and compositional of all prepared samples. Analysis of XRD showed that all prepared nano powders were nanocrystalline and had new [(Cu1-x-Cox)- TiO2 ], rutile and anatase phase depending on the molarity. Further studies have shown that the arrangement of tetragonal and rhombohedral crystals for TiO2 and (Cu1-x-Cox)- TiO2 for x = 0.1 M and 0.9 M respectively, with an average crystallite size of 7.362 nm for TiO2 and 27 nm for (Cu1-x-Cox)- TiO2 for x = 0.1 M and 0.9 M . The SEM analysis shows that the NPs for pure is spherical in form and doped TiO2 have an irregular shape with an average grain size of 168 nm and 223 nm. Analysis of the EDS confirms the chemical composition of the Ti and O elements of the NPs. The difference in the indirect band gap of 3.07 eV, 2.74 eV and 3.58 eV for TiO2 NPs, (Cu0.9-Co0.1)-TiO2 NPs and (Cu0.1-Co0.9)-TiO2 NPs is shown by Tauc’s plots. Here it is noted that the maximal absorption (λm) showed a red shift in the UV–vis absorption spectrum due to doping. Photocatalytic activity was assessed by monitoring Eriochrome Black T (EBT) degradation under UV light. The EBT dye photocatalytic degradation results were 57.75%, 73.7% and 73 %for TiO2 NPs, (Cu0.9-Co0.1)-TiO2 NPs and (Cu0.1-Co0.9)-TiO2 NPs for 110 min, respectively, under UV irradiation. These findings indicate that doping with copper and cobalt improves TiO2’s photodegradation quality.

Removal of anionic dye Eriochrome Black-T using nanocomposites derived from slag

The present investigation highlights slag based nanocomposites in the removal of the anionic dye Eriochrome Black T (EBT) an anionic dye with azo group (-N=N-) that is used as a dyeing agent in tex...

Uptake of an anionic dye from aqueous solution by aluminum oxide particles: Equilibrium, kinetic, and thermodynamic studies

Naturally occurring, abundant alumina particles were used as a low-cost and eco-friendly adsorbent for the removal of Eriochrome Black T (EBT) dye from an aqueous environment. The surface morphology, crystallinity and elemental analysis composition of the alumina before and after the adsorption process were investigated using SEM-EDX, FTIR and DRX techniques. The alumina surface charge was examined by the electrokinetic measurement. The impact of the physico-chemical factors on the adsorption process was studied. The adsorption experiments were performed using a batch reactor. The fitted models were plotted for adsorption kinetic and isotherm studies based on the experimental results. The adsorption data were well described by a pseudo-second order kinetic model, and the adsorption isotherms agreed well with the Langmuir model. The maximum adsorption capacity (qmax) of alumina for the EBT dye was found to be 45 mg/g, corresponding to a removal percentage of 71%. The EBT adsorption phenomena was endothermic and spontaneous. The regeneration tests indicated that the alumina reveal an superb recycling capability. Therefore, this result shows that the alumina particles can be applied as a natural encouraging adsorbent for the removal of anionic dye from aqueous solution. The EBT dye adsorption mechanism can be controled by electrostatic attractions.

Comparative analysis of RSM, ANN and ANFIS and the mechanistic modeling in eriochrome black-T dye adsorption using modified clay

• Preparation and characterization of clay. • Detailed predictive modeling of the EBT adsorption process utilizing RSM, ANN and ANFIS models. • Critical comparative analysis of the three models. • Evaluation of mechanistic modeling of the adsorption process. • Optimization using genetic algorithm. The application of artificial neural network (ANN), response surface methodology (RSM), and adaptive neuro-fuzzy inference system (ANFIS) in modeling the uptake of Eriochrome black-T (EBT) dye from aqueous solution using Nteje clay was the focus of this work. Acid activation with hydrochloric acid (HCl) was used to prepare the adsorbent while Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were utilized in the characterization of the adsorbent. The ANN, RSM, and ANFIS models were analyzed by considering the adsorbent dosage, contact time, solution temperature, and pH of the adsorption process. Sensitivity analyses involving six statistical error functions were further used to compare the acceptability of the models. Four mechanistic models (Weber and Morris, Film diffusion, Bangham, and Dummwald-Wagner models) were used to determine the mechanism of the EBT uptake. The result showed that the activation process enhanced the adsorption capacity of the clay. The ANFIS, ANN, and RSM models gave a high accuracy in predicting the adsorption of the EBT dye with correlation coefficients of 0.9920, 0.9910, and 0.9541, respectively. Further statistical indices lent credence to ANFIS as the best predictive model and RSM the least in adsorption of EBT dye. Process optimization using genetic algorithm gave optimum adsorption efficiency of 95.8%. Mechanistic modeling indicated film diffusion as the rate-limiting mechanism. The maximum amount of EBT adsorbed was 24.04 mg/g. The HCl-modified clay could be utilized as an efficient adsorbent in EBT uptake from wastewater.

Synthesis of zeolite Y @ metal–organic framework core@shell

COOH-modified zeolite Y was prepared via hydrothermal method and used as a core to induce the growth of MIL-53(Al) metal–organic framework (MOF) on its surface at room temperature. The Y@MIL-53 core@shell was applied to adsorption of Eriochrome Black-T (EBT) anionic dye. The materials were characterized using a range of techniques. The attached carboxylic linkers in zeolite Y were confirmed by FT-IR spectroscopy. TEM image of the Y@MIL-53 consisted of two regions, a dark region related to zeolite Y and a light part with an average diameter of 60 nm that related to the MIL-53 shell. The zeta potential indicated the zero point charge (pHPZC) of the core@shell was 4.6. The Y@MIL-53 core@shell showed highest adsorption percent. The possible mechanism of adsorption was proposed. The used adsorbent can be reused for adsorptive removal through simply washing.

Removal of anionic dyes from aqueous media by using a novel high positively charged hydrogel with high capacity

Poly((methacryloylamino)propyl trimethylammonium chloride-co-vinylimidazole) (p(MAPTAC-co-VI)) hydrogels were synthesized through free radical polymerization of 3-(methacryloylamino)propyl trimethylammonium chloride (MAPTAC) and 1-vinylimidazole (VI) in aqueous solutions with ammonium persulfate (APS) used as initiator and N,N′-methylenebis(acrylamide) (MBA) as the crosslinking agent. By modifying with HCl, the positive charge density on the hydrogel network structure was increased and quaternized hydrogels (p(MAPTAC-co-VI)-q) were obtained. Traditional swelling and spectrophotometric characterization techniques were used to gain a better understanding of the performance of cationic hydrogels for the removal of anionic dyes. FTIR, SEM, and EDX confirmed the structure of the hydrogel before and after the adsorption process. Later, dye adsorption performance of these p(MAPTAC-co-VI)-q hydrogels was investigated under different adsorption conditions, including initial concentration, temperature, pH values of dye solutions, and adsorption contact time, adsorbent dosage and in real water samples. Various isotherm and kinetic models of dye adsorption by the hydrogel were also studied and the experimental adsorption followed a pseudo-second order model and fitted the Langmuir isotherm well. Thanks to the effective use of existing adsorption sites, high adsorption capacity was achieved for eriochrome black T (EBT) and methyl orange (MO) dyes. The values of qmax are as follows: 1818.2 mg/g and 1449.3 mg/g, respectively. Thermodynamic parameters indicate that the process was spontaneous and endothermic. P(MAPTAC-co-VI)-q hydrogels can be used as a potential adsorbent for removal of anionic dye molecules, one of the industrial pollutants, from wastewater.

Ultrasonically enhanced dye removal using conducting polymer functionalised ZnO nanocomposite at near neutral pH: kinetic study, isotherm modelling and adsorbent cost analysis

ABSTRACT Alarming increase in water pollution due to the disposal of industrial wastewater loaded with toxic dye has become one of the serious environmental problems since last few decades. Thus in recent years, development of highly functionalised novel composite materials for dye loaded wastewater remediation has become an important area of research. In this study, a conducting polymer (polyaniline) functionalised ZnO nanocomposite (PAn/ZnO-PNC) was synthesised and investigated its adsorptive behaviour for the removal of an anionic dye Eriochrome Black T (EBT) under ultrasonic irradiation. The synthesised PAn/ZnO-PNC was characterised by various analytical techniques such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy (FESEM), Transmission electron microscopy (TEM) and Brunauer–Emmett–Teller (BET) surface area analysis. Experimental results demonstrated that after the functionalization of ZnO with polyaniline the adsorption capacity of PAn/ZnO-PNC improves as compared to pure polyaniline as well as pure ZnO nanoparticles. In addition to that, adsorption of EBT dye with PAn/ZnO-PNC could yield to lesser solution pH dependency as compared to pure ZnO nanoparticles and the optimum solution pH was fixed at 6.0 for EBT dye adsorption using PAn/ZnO-PNC. The adsorption mechanism between EBT dye and PAn/ZnO-PNC can be explained by electrostatic attraction, hydrogen bonding, and stronger π-π interaction bond between nanocomposite and dye molecules. The adsorption kinetic data were well fitted with the pseudo-second-order kinetic model which designates chemisorption between EBT dye molecules and PAn/ZnO-PNC. Isotherm study explores that EBT dye adsorption onto PAn/ZnO-PNC follows the Langmuir isotherm model with a maximum monolayer capacity of 108.69 mg/g. Performance evaluation study explores that sono-assisted adsorption was much superior to conventional magnetic stirring and batch stirring aided adsorption techniques. Cost analysis of synthesised PAn/ZnO-PNC revealed that the preparation cost of the composite is ~65$/kg.

Preparation of porous biochar by urine assisted pyrolysis of sewage sludge and their application for Eriochrome Black T adsorption

Urine, which is composed of water, urea and mineral substance, has been treated as a kind of wastewater for a long time. In this work, urine was used as a novel activator for sludge activation and porous carbon preparation. The pyrolysis was implemented for urine transformation and sludge carbonization. It was found that urine was firstly converted to pore template g-C3N4 at 550℃ and g-C3N4 was in situ decomposed to form pores at 650℃ in the 2nd stage. The influence of pyrolysis temperature in each stage and urine to sludge ratio on properties of carbon was systematically investigated by using thermogravimetric analysis, N2 adsorption-desorption technique and transmission electron microscope. The maximum specific surface area of the produced carbon was 253 m2 g−1, which was equivalent to the carbon prepared by traditional H3PO4 activation. The carbon also had higher adsorption capacity (19.1 mg g−1) to a typical dye Eriochrome Black T (EBT) and meanwhile showed strong stability and reusability in the repeated adsorption cycles. The implementation of using urine as bio-waste activator for porous carbon preparation would have important implications for waste recycle and reutilization.

Investigation of NLO Properties of Eriochrome Black T Colloidal Solution: Role of Surfactant and Reverse Micelles

The photophysical and nonlinear optical properties of Eriochrome Black T (EBT) in micelles, with two charge types of surfactant and reverse micelles (RMs) in a wide range of sizes, were investigated via ultraviolet–visible absorption, fluorescence spectroscopy, and a Z-scan technique. Accordingly, a significant redshift in absorbance and fluorescence quenching of the EBT was observed with an increase in cetyltrimethylammonium bromide (CTAB) concentration. Comparably, the nonlinear absorption coefficient (β) of the EBT decreased following an increase in cationic CTAB concentration, due to an increasing trend in the CTAB:EBT complex in the solution, and it decreased following an increase in anionic aerosol OT concentration. The same behavior was further detected for the nonlinear index of refraction (n2). The β value of the EBT also decreased with an increase in the size and concentration of the RMs, while the n2 was enhanced.

Cobalt ferrite nanoparticles prepared by microwave hydrothermal synthesis and adsorption efficiency for organic dyes: Isotherms, thermodynamics and kinetic studies

Magnetic nanoferrites (MFe2O4, M = Co, Ni) were successfully synthesised through microwave-hydrothermal route, characterised and used for adsorption of Eriochrome Black T (EBT) and Bromophenol Blue (BRB) dyes from their aqueous solution. The powder XRD patterns confirmed the formation of cubic spinel structure for both the ferrites. Under identical conditions, the adsorption efficiency of CoFe2O4 was found relatively higher than the corresponding NiFe2O4. Further characterisations revealed that CoFe2O4 sample was nearly spherical in size (8–9 nm) with narrow size distribution. The sample showed superparamagnetic behaviour with saturation magnetization (Ms) value (66.4 emu/g). BET surface area calculated for the synthesized cobalt ferrite as 70.9 m2/g. Batch adsorption experiments as a function of initial dye concentration, pH, contact time and adsorbent dose showed the adsorption of dyes depends on pH. Equilibrium adsorption data were well explained by both Langmuir and Freundlich isotherm models. The maximum monolayer adsorption capacities (Qo) were found to be 82.6 and 25.6 mg/g for EBT and BRB dyes, respectively. Kinetics of the adsorption was best described by pseudo-second-order model. Various thermodynamic parameters such as ΔG, ΔH and ΔS derived from adsorption data over the temperature range 20–50 °C, accounted for a favourable, spontaneous, endothermic physisorption process. The materials showed potential for repeated use without significant decrease in adsorption capacity after proper regeneration.

An overview on alginate based bio-composite materials for wastewater remedial

Rapid industrialization has become the biggest threat for living beings and aquatic animals, the discharge of contaminants in water bodies is a major concern worldwide. In this work, the various low-cost adsorbents of the alginate-based bio-composites beads such as Oxide-based alginate composites, hybrid or agricultural composites, nanocomposites etc. have been reviewed. The composites discussed have been successfully eliminated the water-soluble contaminants like heavy metal ions such as Cadmium (Cd) and Arsenic (As), Cobalt (Co), lead (Pb2+); water-soluble antibiotics; Organic dyes like methylene blue, methyl orange, Eriochrome black-T; Eriochrome Blue Black R; phenolic compounds of 2,4-dichlorophenol, bisphenol A etc. by adsorption techniques. Methylene Blue removal have been researched in a wide range with alginate-based bio-composites. The Structural analysis and morphology for variety of Alginate Bio-composite beads was performed using Fourier-Transform Infrared Spectroscopy, Scanning Electron Microscope, Brunauer–Emmett–Teller (BET), X-Ray Diffraction (XRD) and Thermogravimetric Analysis techniques. Various Adsorption rates like pseudo-first and second-order, Freundlich Adsorption Isotherm, Langmuir Adsorption Isotherm etc were determined to recognize and improve the differing physiochemical processes such as adsorption rate by adsorbents, pH, initial concentration of dyes, temperature. This review article illustrates the role of natural biopolymer of Na or Ca Biocomposites of alginate in as formats to make valuable substances with extensive applications for the expulsion of different contaminants from wastewater.

The coupled AgI/BiOI catalyst: Synthesis, brief characterization, and study of the kinetic of the EBT photodegradation

The relatively novel AgI/BiOI coupled system (CS) was prepared in-situ by mechanical mixing of the as-synthesized AgI and BiOI nanoparticles (NPs) and characterized by various characterization techniques such as XRD, SEM-EDX, and UV–Vis DRS. XRD results showed the hexagonal crystals of AgI and the tetragonal crystals of BiOI in the CS. The grain sizes of 34.1 and 25.6 nm were estimated for the CS by the Scherrer and Williamson-Hall equations, respectively. The bandgap values of 2.7, 1.75, and 1.83 were estimated based on absorption edge wavelengths for AgI, BiOI, and CS samples, respectively. The CS showed a boosted photocatalytic activity towards Eriochrome Black T (EBT). This boosted activity depends on the amounts of the CS-ingredients and the CS with an AgI:BiOI mole ratio of 1:2 showed the highest activity. The photodegradation rate constant of 0.0167 min−1 with a t1/2 value of 41.5 min was obtained from the Hinshelwood plot. Further, the mineralization rate constant of 0.0137 min−1 with a t1/2 value of 50.6 min was obtained by applying the COD results in the Hinshelwood model.

Synthesis and characterization of SnO2 NPs for photodegradation of eriochrome black-T using response surface methodology.

The domestic and industrial sewage contains an extensive range of various organic compounds. Due to the toxicity of these materials, their degradation is considered one of the great environmental challenges. To address this problem, SnO2 nanoparticles (NPs) were synthesized via a green route, and they were used as an efficient catalyst for the degradation of an organic dye. In the stage of synthesis of nanoparticles, Thymus vulgaris L. extract acted as an efficient capping agent and renewable reducing agent, and SnO2 NPs were synthesized without addition of any hazardous surfactants. The successful synthesis of SnO2 NPs was confirmed by XRD, FT-IR, SEM, EDX, and TEM. The photocatalytic performance of SnO2 NPs was examined for the degradation of eriochrome black-T (ECBT) as a toxic organic dye in aqueous medium under ultraviolet irradiation. Furthermore, the response surface methodology (RSM) with central composite design (CCD) model was carried out to study of the effects of three different operational parameters on degradation of ECBT. In this design, initial pH of solution (3-11), reaction time (0.5-4h), and the catalyst loading (0.05-0.12g) were selected as three factors, whereas the degradation efficiency was chosen as the response. The results of the experimental design indicated that initial pH and catalyst loading were highly significant factors, whereas the reaction time was less important than other factors. Also, recyclability of catalyst was investigated, and the obtained results showed that SnO2 NPs could be easily recovered and reused for at least 4 cycles without any significant decrease in their activity.