A statistical modeling-optimization approach for efficiency photocatalytic degradation of textile azo dye using cerium-doped mesoporous ZnO: A central composite design in response surface methodology

Investigation of Doehlert matrix conception in novel intrinsically conducting polymers based on selenium nanoparticles for wastewater treatment: Synthesis, characterization, kinetic and chemometric study

The synthesis of robust intrinsically conducting polymers (ICPs) based on nanoparticles is becoming increasingly attractive to the research community due to the unique properties of these nanocomposites. Indeed, as organic semiconductors, ICPs combine both polymer and metal properties in a single structure. This study presents an innovative approach in which the Doehlert Matrix (DM) is applied to a novel ICP nanocomposite based on polyaniline (Pani) coupled with selenium (Se) loaded mesoporous titania (TiO2) for wastewater treatment by photocatalysis. It includes both the elaboration routes of ICP nanocomposites, characterization of materials by X-ray diffraction (XRD), BET analysis, thermogravimetric analysis (TGA), RAMAN spectroscopy and Fourier transform infrared spectroscopy (FTIR) and photodegradation of methylene blue (MB) as a representative of dye pollutant. In addition, the photocatalytic process has been optimized by a novel DM conception. The effect of the pH of the solution, the catalyst dosage and the initial pollutant concentration was investigated. The optimum conditions were found to be: initial MB concentration of 15 mg/L, the catalyst dosage of 69 mg and pH of 9.6 with an operating time of 75 min, with a coefficient of determination R2 equal to 0.9985. The removal efficiency of BM was close to 97 %. The study shows that the new ICP nanocomposites improve the photocatalytic efficiency compared to pure titania and/or pure Pani. In addition, as the ternary Pani-Se-TiO2 nanocomposite could be obtained from a low-cost synthesis, it is a very promising material for use in wastewater treatment.

Different solvents and organic modifiers for the control of crystallographic parameters in nano-crystallite hydroxyapatite for amplification of photocatalytic activity

In this research, HAp nanocrystals were synthesized using conventional wet chemical precipitation methods using various organic modifiers, including urea, palmitic acid, and naphthalene. Ethanol and isopropyl alcohol (IPA) were used as solvents in this process. Different characterization techniques, namely X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV-vis absorption spectroscopy, were employed to ascertain the formation of HAp nanocrystals. Numerous structural parameters, including lattice parameters, unit cell size, volume of the unit cell, specific surface area, degree of crystallinity, dislocation density, macrostrain, and crystallinity index, were assessed using XRD data. The linear straight-line method of Scherrer's equation, Monshi-Scherrer's method, the Williamson-Hall method, the size-strain plot method, the Halder-Wagner method, and Sahadat-Scherrer's model were applied to compute the crystallite size of the synthesized HAp samples. All the synthesized HAp has crystalline structures within the permissible range of 1-150 nm which were estimated from the XRD data using the mentioned models. However, the values for strain (from -3 × 10-4 to 6.4 × 10-3), strain (from -9.599 × 104 to 7 × 1010 N m-2), and energy density (from -11 × 1011 to 2 × 107 J m-3) were also calculated for the synthesized samples. In addition, the optical band gap energy of the synthesized HAp was computed (5.89 to 6.19 eV). The synthesis media have a control on the crystallographic planes, e.g. in the case of the ethanol medium, the (110) plane exhibited significant intensity (which could potentially serve as a driving force for enhancing photocatalytic activity). The use of 100% ethanol HAp yields the most favorable outcome regarding both the degradation percentage (91.79%) and degradation capacity (7%) for the Congo red dye.

Central composite design and mechanism of antibiotic ciprofloxacin photodegradation under visible light by green hydrothermal synthesized cobalt-doped zinc oxide nanoparticles

In this research, different Co2+ doped ZnO nanoparticles (NPs) were hydrothermally synthesized by an environmentally friendly, sustainable technique using the extract of P. capillacea for the first time. Co-ZnO was characterized and confirmed by FTIR, XPS, XRD, BET, EDX, SEM, TEM, DRS UV-Vis spectroscopy, and TGA analyses. Dislocation density, micro strains, lattice parameters and volume of the unit cell were measured using XRD results. XRD suggests that the average size of these NPs was between 44.49 and 65.69 nm with a hexagonal wurtzite structure. Tauc plot displayed that the optical energy bandgap of ZnO NPs (3.18) slowly declines with Co doping (2.96 eV). Near complete removal of the ciprofloxacin (CIPF) antibiotic was attained using Green 5% of Hy-Co-ZnO in the existence of visible LED light which exhibited maximum degradation efficiency (99%) within 120 min for 30 ppm CIPF initial concentration. The photodegradation mechanism of CIPF using Green Hy-Co-ZnO NPs followed the Pseudo-first-order kinetics. The Green Hy-Co-ZnO NPs improved photocatalytic performance toward CIPF for 3 cycles. The experiments were designed using the RSM (CCD) method for selected parameters such as catalyst dosage, antibiotic dosage, shaking speed, and pH. The maximal CIPF degradation efficiency (96.4%) was achieved under optimum conditions of 39.45 ppm CIPF dosage, 60.56 mg catalyst dosage, 177.33 rpm shaking speed and pH 7.57.

Optimizing backwash control using data on seasonal changes in the invertebrate community of granular activated carbon filters

Problems associated with the colonization and leakage of invertebrates in the granular activated carbon (GAC) filters of waterworks have received increased attention in recent years. To study the effect of environmental factors and water quality on invertebrate abundances, and the backwash control for minimizing invertebrate abundance. A survey of the invertebrate community of GAC filters was carried out monthly from March 2021 to May 2022. A pilot-scale GAC system established in the laboratory alongside a lake, with a volume of 35.3 L. 45 invertebrate species were detected, and 40 of these were rotifers. Significant variation in abundance was observed among seasons before and after GAC filtration, the average invertebrate abundance in the inlet water was 11.1 times that in the filtrate. The GAC filter contained invertebrates that might be responsible for the large number of organisms in the filtrate. Invertebrate abundance in the GAC filter decreased gradually with the carbon layer depth, which the mean invertebrate abundances were 6,926, 5,232, and 3818 ind./kg in the top layer (TL), middle layer (ML), and bottom layer (BL), respectively. Invertebrate abundance was correlated with water temperature and varied seasonally. Among eight water quality parameters, chlorophyll a (Chla) and the total plate count (TPC) were most significantly correlated with invertebrate abundance. According to the statistical modeling and the optimization process of response surface methodology (RSM). The predicted optimal values were a flow rate of 6.36 L/h, a backwash cycle of 3.26 d, and a backwash intensity of 14.97 L/(m2·s) for a minimum invertebrate abundance of 3013 ind./kg in the GAC filter. To maintain invertebrate abundance within an acceptable range, some of these measures might need to be modified depending on the actual conditions.

Effective visible-light-driven photocatalytic degradation of fenitrothion by s-gC3N4/Ag-Au bimetallic nanocomposite

This paper reports on the optimization of fenitrothion photocatalytic degradation in visible light based on Plackett Burman (PB) design and central composite design (CCD) in response surface methodology (RSM). A herbicide routinely used with a negative impact on the environment is fenitrothion, which must be degraded to minimize the impact on the environment. For fenitrothion degradation, Ag-Au bimetallic nanoparticles on the semiconducting s-doped gC3N4 surface were synthesized using the galvanic exchange. The properties of s-gC3N4/Ag-Au bimetallic nanocomposite were confirmed by various methods. Significant factors responsible for fenitrothion photocatalytic degradation were determined using Plackett-Burman (PB) design and were catalyst dosage, initial fenitrothion concentration, H2O2 concentration, pH, and rotational speed. Central composite design (CCD) design was used for further optimization. The optimum conditions for the maximum degradation of fenitrothion (100%) constraints were found to be 100% an amount of H2O2 concentration 60 mM, pH 10, rotational speed 700 rpm. These results showed that s-gC3N4/Ag-Au bimetallic nanocomposite could act as a suitable photocatalyst under visible light in the degradation of fenitrothion. By removing fenitrothion from real water samples, as well as by maintaining its stability and reusability in five successive cycles, the practicality of this nanocomposite was demonstrated.

A Comprehensive Review on the Boosted Effects of Anion Vacancy in the Heterogeneous Photocatalytic Degradation, Part II: Focus on Oxygen Vacancy

Environmental problems, including the increasingly polluted water and the energy crisis, have led to a need to propose novel strategies/methodologies to contribute to sustainable progress and enhance human well-being. For these goals, heterogeneous semiconducting-based photocatalysis is introduced as a green, eco-friendly, cost-effective, and effective strategy. The introduction of anion vacancies in semiconductors has been well-known as an effective strategy for considerably enhancing the photocatalytic activity of such photocatalytic systems, giving them the advantages of promoting light harvesting, facilitating photogenerated electron-hole pair separation, optimizing the electronic structure, and enhancing the yield of reactive radicals. This Review will introduce the effects of anion vacancy-dominated photodegradation systems. Then, their mechanism will illustrate how an anion vacancy changes the photodegradation pathway to enhance the degradation efficiency toward pollutants and the overall photocatalytic performance. Specifically, the vacancy defect types and the methods of tailoring vacancies will be briefly illustrated, and this part of the Review will focus on the oxygen vacancy (OV) and its recent advances. The challenges and development issues for engineered vacancy defects in photocatalysts will also be discussed for practical applications and to provide a promising research direction. Finally, some prospects for this emerging field will be proposed and suggested. All permission numbers for adopted figures from the literature are summarized in a separate file for the Editor.

An experimental design study of photocatalytic activity of the Z-scheme silver iodide/tungstate binary nano photocatalyst

A binary AgI/ Ag2WO4 photocatalyst was fabricated and characterized by SEM, XRD, UV-Vis DRS, and FT-IR. It was then used to photodegrade sodium ceftriaxone (CTX) in an aqueous solution. The band gap energies of 2.95, 2.78, and 2.62 eV were obtained by the Kubelka-Munk model for Ag2WO4, AgI, and AgI/Ag2WO4 catalysts. The samples have pHPZC values of 6.9, 4.2, and 6.6, respectively. The synergistic photocatalytic activity of the coupled system depended on the AgI:Ag2WO4 mole ratio and grinding time (optimums:mole ratio of 4:1 and time 30 min). The experimental design was used for optimizing the conditions and a quadratic model well-processed the data based on the model F value of 131.87 > F0.05,14,13 = 2.55 and LOF F value of 0.78 < F0.05,10,3 = 8.78. The optimized RSM run included the irradiation time of 85 min, 3.5 mg/L of CTX sample at pH 9, and a catalyst dose of 1.0 g/L. Under the optimized conditions, about 63% of CTX molecules were photodegraded. In the study of the scavenging agents, the direct Z-scheme mechanism accumulated electrons in the CB-AgI and the holes in the VB-Ag2WO4 level, as stronger reducing and oxidizing centers than the accumulated electrons and holes of the type (II) heterojunction mechanism. Compared to a CTX oxidation potential of about 0.06 V, the direct Z-scheme mechanism is more favorable to reduce or oxidize it.

Evaluation of the photodegradation activity of bismuth oxoiodide/bismuth sub-carbonate nanocatalyst: Experimental design and the mechanism study

In this study, a binary BiOI/(BiO)2CO3 catalyst was prepared and used for sulfasalazine (SSZ) photodegradation in an aqueous phase. The semiconductors were identified by XRD, SEM-EDX, and UV-Vis diffuse reflectance spectroscopy (DRS) methods. Applying the Kubelka-Munk model on DRS results, the band gap energies of 2.09, 3.5, and 2.07 eV were obtained for BiOI, (BiO)2CO3, and BiOI/(BiO)2CO3 samples. pHpzc values of 6.3, 10.1, and 8.1 were estimated for BiOI, (BiO)2CO3, and BiOI/(BiO)2CO3, respectively. After observing the boosted photocatalytic activity by the coupled system, the interaction effects of the influencing variables in SSZ photodegradation were evaluated via the response surface methodology (RSM) approach. The optimal RSM-run conditions were 8.5 ppm SSZ at pH 8, which contained 0.28 g/L of the BiOI/(BiO)2CO3 catalyst and 29 min illumination time, resulting in 87% SSZ photodegradation. The effects of some scavenging agents were also studied to elucidate the relative roles of the reactive species in the SSZ photodegradation by the proposed catalyst, that is, hydroxyl radicals ∼ photoinduced electrons > superoxide radicals ∼ photoinduced holes. The proposed catalyst retained good activity after 5 successive reusing runs.

Anar Phali (Opuntia ficus) juice extract as a novel pollution-free source of natural betalain dye for wool yarn

Green products such as plant pigments in all filed are gaining fame globally due to their excellent ayurvedic and biological characteristics. In this study, microwave rays have been employed for the isolation of colorants from Anar Phali while bio-mordant have been included to get color-fast shades. The colorant was isolated in an acidic medium before and after microwave rays for 2 min. For getting darker shades with different tints, sustainable chemical and plant-based extracts as bio-mordant have been employed before and after bio coloration of wool yarn at given conditions. CIE Lab system computed in Colori-spectrophotometer (CS-410) was used to observe the change in color depth and tonal variation of dyed fabrics, and ISO standard methods have been employed to rate the colorfastness to light, washing, and rubbing at grey scale. It is concluded that microwave rays have an excellent sustainable efficacy to isolate colorant from Anar Phali powder for wool dyeing, whereas the addition of bio-mordants has made the process more sustainable and eco-friendly.

Enhanced photocatalytic performance of CdFe2O4/Al2O3 nanocomposite for dye degradation

In the present work, CdFe₂O₄/Al₂O₃ magnetic nanocomposite photocatalyst is successfully synthesized by simple sol-gel auto-combustion method. The role of this sample is studied as a photocatalyst. The influence of Al₂O₃ concentration with CdFe₂O₄ on the photocatalytic property is also studied. We have considered three weight percentage of Al₂O₃, 5%, 10%, and 20% with CdFe₂O₄. All the samples are characterized with X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) with selected area electron diffraction (SAED), vibrating sample magnetometer (VSM), UV-Visible, and photoluminescence (PL) spectroscopy techniques. The 10% composite sample showed the lower particle size, higher surface area, enhanced porosity, higher saturation magnetization, and considerable band gap as compared to that of 5% and 20% CdFe₂O₄/Al₂O₃ as well as bare CdFe₂O₄ nanoparticles. The photocatalytic activity of the sample is evaluated towards the degradation of the xylenol orange (XO) dye under UV light. The degradation process of the dye is monitored spectrophotometrically. The performance in terms of removal efficiency is studied by varying the contact time, dye concentration and amount of catalyst. Among the three concentrations of Al₂O₃, the 10% weight concentration of Al₂O₃ with CdFe₂O₄ is found to be the optimal concentration and showed the higher degradation rate. After 30 min photocatalytic reaction, the degradation rate is 92.29% for 10% CdFe₂O₄/Al₂O₃ and for bare CdFe₂O₄, it is 85.79%. This work provides a new reference for designing Al₂O₃-based spinel ferrite nanocomposites and their role in wastewater management.

Elimination of toxic azo dye using a calcium alginate beads impregnated with NiO/activated carbon: Preparation, characterization and RSM optimization

Nickel oxide nanoparticles supported activated carbon (AC-NiO) was fabricated using thermal activation. Then, AC-NiO composite was immobilized on alginate beads to obtain 3-dimensional network structure ALG@AC-NiO nanocomposite beads for catalytic reduction of Congo red (CR) dye. The resulting nanocomposite beads were identified by various physical techniques. The crystalline nature and dispersion of NiO nanoparticles was defined by the XRD and EDS techniques, respectively. ALG@AC-NiO beads have a Ni element content of 4.65 wt% with an average NiO particle diameter of 23 nm. The statistical approach mathematically describes the catalytic reduction of the CR dye as a function of the NaBH₄ concentration, the catalyst dose and the concentration of the CR dye modeled by a BBD-RSM. According to the statistical modeling and the optimization process, the catalytic optimum conditions were obtained for NaBH₄ concentration of 0.05 M, catalyst dose of 11 mg and CR dye concentration of 80 ppm who permit meet 99.67 % of CR dye conversion. The adjusted coefficient of determination (R² = 0.9957) indicates that the considered model was quite suitable with a good correlation between the experiment and predicted.

A Z-scheme CdS/Ag3PO4 catalyst: Characterization, experimental design and mechanism consideration for methylene blue

Due to the explosive use of Azo dyes in various industries such as textiles, discharging these industrial effluents into the environment critically polluted water supplies. Accordingly, constructing/developing novel binary catalysts to diminish the pollution extent of such effluents before discharging into environment is an excellent issue in environmental chemistry. Here, a binary CdS/ Ag₃PO₄ was constructed, and its boosted photocatalytic activity was proven against methylene blue (MB), as a model dye pollutant. The Wurtzite CdS and Ag₃PO₄ cubic crystal nanoparticles were synthesized and coupled mechanically. The binary sample's lowest photoluminescence (PL) results confirm a higher e/h separation. DRS results confirmed a decreased energy gap for the coupled system. The semiconductors' VB and CV potentials were calculated and used for constructing of Z-scheme mechanism. The photocatalytic activity was followed via an experimental design approach. The model F-value of 89.75 > F_0.05,14,13 = 2.42 and LOF F-value of 6.57 < F_{0.05,10, 3} = 8.79 reveal that the model well processed data. The optimal run conditions were CMB: 5 ppm, Catalyst dose: 1 g/L, pH: 3.25, and irradiation time: 139 min, at which 85% of MB molecules were degraded. Based on the trend of ascorbic acid > isopropanol > formic acid ≈ nitrate obtained for the scavengers' importance in decreasing the photocatalyst activity, superoxide radicals had the highest effect in MB degradation and then ^•OH. The results showed the direct Z-scheme has the main effect on MB degradation by the binary sample.

Study on characteristics and microscopic mechanism of composite environment-friendly dust suppressant for urban construction site soil fugitive dust based on response surface methodology optimization

Soil fugitive dust pollution caused by urban construction sites is a significant problem. To improve the dust suppression efficiency on the urban construction sites, hydroxypropyl guar (HPG), dodecyl dimethyl amine oxide (OB-2), and hydroxypropyl methylcellulose (HPMC) were selected as individual components of the composite dust suppressant using a single-factor test. The response surface methodology (RSM) was used to determine the optimal mixing proportions. After preparation, the characteristics of the composite dust suppressant were tested. Fourier-transform infrared spectroscopy and scanning electron microscopy (SEM) were used to characterize the composite dust suppressant and explore its mechanism. The results showed that 0.327% HPG, 0.6% OB-2, and 0.5% HPMC were the best compound concentrations. Under optimum conditions, the viscosity of the composite dust suppressant was 151.1 [Formula: see text], penetration time was 61.4 s, and water retention rate was 30.67%. Compared with traditional dust control by spraying water, it showed better resistance to evaporation at high temperatures and better wind erosion resistance. The antievaporation rate was 39.42% at 60 °C. After 11 d of continuous wind erosion at level 7, the wind erosion resistance rate was as high as 98.24%. The reason for the excellent dust suppression effect of the composite dust suppressant is that the methyl and hydroxyl groups in the solution diffuse to the surface of the soil fugitive dust particles using Brownian motion and gradually approach the corresponding groups in the soil fugitive dust particles. When the distance between the two reaches 10 [Formula: see text], adsorption occurs, causing small dust particles to stick together. Because of the stability of the covalent bonds in the methyl and hydroxyl groups, a stable solidified layer is formed on the soil fugitive dust surface after the evaporation of the composite dust inhibitor solution, thereby avoiding secondary dust. In addition, the composite dust suppressant is noncorrosive and friendly to the construction site environment. Therefore, the composite dust suppressant can effectively reduce soil fugitive dust, alleviate environmental pollution, and provide a reference for preventing and controlling soil fugitive dust on urban construction sites and preparing composite environment-friendly dust suppressants.

Cefotaxime degradation by the coupled binary CdS-PbS: characterization and the photocatalytic process kinetics

Increased water pollution due to discharging industrial/urban/hospital wastewater has been adopted to introduce/develop novel removal techniques/catalyst/adsorbent. The hexagonal (wurtzite) CdS and the cubic PbS nanoparticles (NPs) were synthesized, coupled, and supported onto clinoptilolite NPs (CNP). Then, the sample was characterized by X-ray powder diffraction (XRD), diffuse reflectance spectroscopy (DRS), Fourier transform infrared (FTIR), and a scanning electron microscope equipped with an energy dispersive X-ray analyzer (SEM-EDX) techniques. The average crystallite size for CdS NPs, PbS NPs, CNP, and CdS-PbS/CNP samples was obtained at about 24, 36, 27, and 14 nm using the Scherrer formula value of nanometer, by the W-H formula, 31, 17, 39, and 51, respectively. Only a detectable slope can be observed from the DRS spectra for CdS NPs at 591 nm corresponding to an Eg value of 2.1 eV. PbS NPs have a broad abruption peak that begins from the visible region and extends to the IR region of the light. A boosted photocatalytic activity of the supported binary catalysts towards cefotaxime (CT) was reached. An apparent first kinetic model was reached with a k-value of 0.021 min^-1 corresponding to the t_1/2 value of 33 min. A decreased COD trend for the photodegraded CT solutions was reached, and the chemical oxygen demand (COD) results in the Hinshelwood model showed a k-value of 0.016 min^-1, corresponding to a t_1/2 value of 43 min.

Machine learning approaches to predict the photocatalytic performance of bismuth ferrite-based materials in the removal of malachite green

This study focuses on the potential capability of numerous machine learning models, namely CatBoost, GradientBoosting, HistGradientBoosting, ExtraTrees, XGBoost, DecisionTree, Bagging, light gradient boosting machine (LGBM), GaussianProcess, artificial neural network (ANN), and light long short-term memory (LightLSTM). These models were investigated to predict the photocatalytic degradation of malachite green from wastewater using various NM-BiFeO₃ composites. A comprehensive databank of 1200 data points was generated under various experimental conditions. The ten input variables selected were the catalyst type, reaction time, light intensity, initial concentration, catalyst loading, solution pH, humic acid concentration, anions, surface area, and pore volume of various photocatalysts. The MG dye degradation efficiency was selected as the output variable. An evaluation of the performance metrics suggested that the CatBoost model, with the highest test coefficient of determination (0.99) and lowest mean absolute error (0.64) and root-mean-square error (1.34), outperformed all other models. The CatBoost model showed that the photocatalytic reaction conditions were more important than the material properties. The modeling results suggested that the optimized process conditions were a light intensity of 105 W, catalyst loading of 1.5 g/L, initial MG dye concentration of 5 mg/L and solution pH of 7. Finally, the implications and drawbacks of the current study were stated in detail.

The boosted photocatalytic effects of a zeolite supported CdS towards an antibiotic model pollutant: a brief kinetics study

In recent decades, increased world population and industrial activities explosively polluted our environment, especially the aquatic resources. This requires introducing/developing novel methods to decrease the pollution extent of such resources. Here, the hexagonal (wurtzite) CdS nanoparticles (NPs) were synthesized and supported onto ball-mill prepared clinoptilolite NPs (CNP). Samples were briefly characterized by X-ray powder diffraction (XRD), Fourier transform infrared (FTIR), scanning electron microscope equipped with an energy dispersive X-ray analyzer (SEM-EDX), and diffuse reflectance spectroscopy (DRS) techniques. The average crystallite size for CdS NPs and CdS-CNP samples was estimated to be about 9.0 nm and 12.3 nm (from the Scherrer formula) and about 19.7 and 17.5 nm (from the Williamson-Hall model), respectively. From the DRS spectra, the absorption wavelengths of 595 and 546 nm correspond to band gap energies of 2.08, and 2.27 eV was obtained for CdS NPs and CdS-CNP samples. The samples were then used in the photodegradation of cefotaxime (CT), and the results showed a boosted photocatalytic activity for CdS-CNP rather than CdS NPs. The photodegradation process obeyed the pseudo-first-order kinetic model, and the CdS and CdS-CNP catalysts obtained the k-values of 0.013 min^-1 and 0.023 min^-1. When the photodegraded CT solutions were used in COD experiments, the k-values changed to 0.011 min^-1 and 0.029 min^-1, respectively. The zeolite support is an eco-friendly natural zeolite with abundant deposits in Iran that yields a cost-effective method.

A mechanistic study of the photocatalytic activity of AgI–WO3 in an experimentally designed approach toward methylene blue photodegradation

The visible light-active AgI/WO3 binary photocatalyst has been characterized using XRD, FTIR spectroscopy, SEM-EDX, cyclic voltammetry (CV), photoluminescence (PL), and UV–vis DRS techniques.

Boosted photocatalytic effect of binary AgI/Ag2WO4 nanocatalyst: characterization and kinetics study towards ceftriaxone photodegradation

In modern chemistry, great interest has been paid to introducing outstanding photocatalysts for degrading organic pollutants. Herein, a highly efficient binary AgI/Ag₂WO₄ photocatalyst was prepared from AgI and Ag₂WO₄ nanoparticles (NPs) and characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), UV-Vis diffuse reflectance spectroscopy (DRS), electrochemical impedance spectroscopy (EIS), and Fourier transform infrared (FT-IR) techniques. In the Scherrer model, the average crystallite sizes of 34.9, 42.0, and 24.1 nm were estimated for the AgI, Ag₂WO₄, and the binary catalyst, while the values were 91, 13, and 85 nm by the Williamson-Hall model. FTIR confirmed the presence of W-O-W, O-W-O, Ag-I, and O-Ag-O bonds in the coupled material. DRS results showed absorption edge wavelengths of 451, 462, and 495 nm (corresponding to the band gap values of 2.75, 2.68, and 2.51 eV) for Ag₂WO₄, AgI, and AgI/Ag₂WO₄ catalyst, respectively. Synergistic photocatalytic activity of the coupled system was achieved towards ceftriaxone (CTX) in an aqueous solution (about 33% 10 ppm CTX solution was degraded without any optimization in the initial conditions of catal dose 0.3 g/L (Ag₂WO₄:AgI with mole ratio 1:2 and 30 min abrasion time), and irrad. time 45 min, C_CTX). This boosted effect depended on the AgI:Ag₂WO₄ mole ratio and grinding time for the mechanical preparation of the binary catalyst (optimums: mole ratio of 4:1 and time 30 min). The photodegradation kinetics obeyed the Hinshelwood model with the apparent first-order rate constant (k) of 0.013 min^-1 (t_1/2 = 53.30 min). Performing the COD on the photodegraded CTX solutions got a Hinshelwood plot with a slope of 0.019 min^-1 (t_1/2 = 36.5 min).

Cerium Oxide Nanorods Synthesized by Dalbergia sissoo Extract for Antioxidant, Cytotoxicity, and Photocatalytic Applications

In this study, cerium oxide nanorods (CeO₂-NRs) were synthesized by using the phytochemicals present in the Dalbergia sissoo extract. The physiochemical characteristics of the as-prepared CeO₂-NRs were investigated by using ultraviolet-visible spectroscopy (UV-VIS), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction analysis (XRD). The SEM and UV-VIS analyses revealed that the acquired nanomaterials possessed a rod-like morphology while the XRD results further confirmed that the synthesized NRs exhibited a cubic crystal lattice system. The antioxidant capacity of the synthesized CeO₂-NRs was investigated by using several in vitro biochemical assays. It was observed that the synthesized NRs exhibited better antioxidant potential in comparison to the industrial antioxidant of the butylated hydroxyanisole (BHA) in 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. The biochemical assays, including lipid peroxidation (LPO), total antioxidant capacity (TAC), and catalase activity (CAT), were also performed in the human lymphocytes incubated with the CeO₂-NRs to investigate the impact of the NRs on these oxidative biomarkers. Enhanced reductive capabilities were observed in all the assays, revealing that the NRs possess excellent antioxidant properties. Moreover, the cytotoxic potential of the CeO₂-NRs was also investigated with the MTT assay. The CeO₂-NRs were found to effectively kill off the cancerous cells (MCF-7 human breast cancer cell line), further indicating that the synthesized NRs exhibit anticancer potential as well. One of the major applications studied for the prepared CeO₂-NRs was performing the statistical optimization of the photocatalytic degradation reaction of the methyl orange (MO) dye. The reaction was optimized by using the technique of response surface methodology (RSM). This advanced approach facilitates the development of the predictive model on the basis of central composite design (CCD) for this degradation reaction. The maximum degradation of 99.31% was achieved at the experimental optimized conditions, which corresponded rather well with the predicted percentage degradation values of 99.58%. These results indicate that the developed predictive model can effectively explain the performed experimental reaction. To conclude, the CeO₂-NRs exhibited excellent results for multiple applications.

A Z-scheme CdS/BiVO4 photocatalysis towards Eriochrome black T: An experimental design and mechanism study

The synergistic photocatalytic activity was obtained when CdS and BiVO₄ nanoparticles (NPs) were coupled. The samples were characterized by XRD, FTIR, SEM-EDX, and UV-DRS techniques, and their pHpzc was also estimated. The crystallite size of the coupled sample was estimated at 37.3 and 12.5 nm by the Scherrer and Williamson-Hall equations, respectively. The band gaps and the potential positions of VB and CB levels of the semiconductors used were determined. The highest boosted photocatalytic activity was obtained when the CdS: BiVO₄ mole ratio was 1:1. RSM studied the simultaneous interactions between the selected variables, and the model F-value of 110.61> F_{0.05, 14, 13} = 2.4 accompanied by the LOF F-value of 5.20 < F_{0.05, 10, 3} = 8.79 confirm the model significance. The correlation coefficients of R² = 0.9861, the adjusted R² = 0.9710, and the predicted R² = 0.9417, also establish a satisfactory model for processing the experimental data. In the scavenging agent study, photodegradation mechanisms were suggested; among them, the direct Z-scheme mechanism is more favorable for illustrating the EBT-photodegradation by the binary CdS-BiVO₄ photocatalyst. The proposed system, especially the direct Z-scheme mechanism, is suitable as a potential hydrogen production system.

Optimization, kinetics, and thermodynamics aspects in the biodegradation of reactive black 5 (RB5) dye from textile wastewater using isolated bacterial strain, Bacillus albus DD1

This study is aimed to model and optimize the decolorization of reactive black 5 (RB5) dye using Bacillus albus DD1. The response surface methodology (RSM) along with rotatable central composite design (rCCD) is used to optimize the response, % decolorization with four input variables: (i) pH (5-9), initial dye concentration (50-500 ppm), the composition of yeast extract as nitrogen source (0.2-1%) and amount of bacterial inoculum (5-25% v/v). The % decolorization is predicted to be ≈ 98% at the optimized condition (pH = 7.6, dye concentration = 200 ppm, bacterial inoculum = 20 v/v% and yeast extract = 0.4%). Furthermore, the kinetics and thermodynamics of RB5 degradation are also determined. The kinetic order of biodegradation of RB5 is found to follow first-order kinetics with a kinetic rate constant = 0.0384. The activation energy, E_a and frequency factor, A values are calculated as 34.46 kJ/mol and 24,343 (1/Day). A thermodynamic study is also carried out at different temperatures (298 K, 308 K, 310 K, 313 K, and 318 K) using optimized conditions. The values of the ΔH and ΔS are found to be +30.79 kJ/mol, and -0.1 kJ/mol/K, respectively using the Eyring-Polanyi equation. The values of ΔG are also calculated at all temperatures.

New insight into the kinetic study on the different loadings of the CuO/CNT catalyst and its optimization for p-chloroaniline photodegradation

The effect of the copper (Cu) content on Cu oxide loaded onto a carbon nanotube (CuO/CNT) catalyst on the mechanistic, kinetic, and photonic efficiency of the photodegradation of p-chloroaniline (PCA) under visible (Vis) and ultraviolet (UV) light irradiation has been explored. For low-loading (1-5 wt%) CuO/CNTs, photodegradation performed better under UV (>84%) rather than the Vis system; this may be due to the presence of abundant defect sites on both CuO and CNTs, which allowed the multielectron reduction of oxygen at their impurity levels to generate more hydrogen peroxide and subsequent ·OH radicals. The active species under UV were in the following order: h⁺ ≫ e^- > ·OH, while it was vice versa for the Vis system with a well-balanced 50 wt% CuO/CNT catalyst that exhibited a similar performance. The kinetic study showed the transition of the kinetic order from the zeroth to the first order on increasing the PCA concentration under the Vis system and vice versa for the UV system. The Thiele modulus (ϕ) further confirmed that the effect of internal mass transfer was negligible under UV light. In contrast, the transition from mass transfer to kinetic control limitation was observed under the Vis system. The optimum PCA degradation predicted from the response surface analysis was 97.36% at the reaction pH of 7.3, catalyst dosage of 0.45 g L^-1, and initial PCA concentration of 11.02 mg L^-1. The condition obtained was fairly close to the forecasted value with an error of 0.26%.

The boosted activity of AgI/BiOI nanocatalyst: a RSM study towards Eriochrome Black T photodegradation

Nowadays, critical environmental pollution needs some novel, simple, effective, and cost-effective catalysts with high efficiency in the visible region of the light. Thus, the AgI/BiOI coupled nanocatalyst sample (CS) was prepared and briefly characterized. The pH_pzc values of 6.2, 5.4, and 4.5 were estimated for AgI, BiOI, and AgI/BiOI samples. Based on the PXRD results, average crystallite sizes of 35.2, 34.7, and 34.1 nm were obtained for AgI, BiOI, and AgI/BiOI samples from the Scherrer formula and 38.3, 25.6, and 25.6 nm by the Williamson-Hall formula. SEM image confirmed a sheet-like BiOI morphology covered by AgI nanoparticles. The simultaneous interactions of the influencing variables on the boosted photocatalytic activity of CS sample towards Eriochrome Black T (EBT) were evaluated by response surface methodology (RSM) (under 100-W tungsten lamp irradiation with 230 mW/m².nm irradiance). The goodness of the model was confirmed by the significance of the model (F value of 65.68 > F_{0.05, 14, 13} = 2.55) and a non-significant LOF (F value of 0.97 < F_{0.05, 10, 3} = 8.79) at a 95% confidence interval obtained in ANOVA analysis of the results. The center point runs have the following conditions: catalyst dose: 0.68 g/L; pH: 7.5; C_EBT: 7.25 mg/L; and irradiation time: 53.5 min, while the optimal run included the following conditions: catalyst dose: 1.0 g/L; pH: 4; C_EBT: 10 mg/L; and irradiation time: 80 min. About 95% of EBT molecules were degraded in the optimal conditions.

A designed experiment for CdS-AgBr photocatalyst toward methylene blue

A boosted photocatalytic activity was observed for the CdS-AgBr nanocomposite in the degradation of methylene blue (MB). The experimental design method based on the response surface methodology (RSM) approach used to study the simultaneous interaction effects between the influencing variables. Analysis of variance (ANOVA) of the results confirmed a significant model for processing the data because an F value of 32.34 for the suggested model was higher than that of the critical value of F_{0.05, 14, 13} = 2.55 at 95% confidence interval. This analysis also showed a non-significant lack of fit (LOF) (as a measure of the randomness of the deviations around the obtained data) because the LOF F value of 8.27 was smaller than that of the critical value of F_{0.05, 10, 3} = 8.79. R² values near to unity were achieved (the multiple correlation coefficients R² (R² = 0.9627), adjusted R² (adj-R² = 0.9226), and predicted R² (pred-R² = 0.7423)). Six center points suggested by the model included the following conditions: pH, 6.1; C_MB, 3.5 mg/L; a dose of the catalyst, 0.68 g/L; and irradiation time, 40.5 min. During the center point runs, the degradation efficiencies were obtained in the range of 38 to 43%. The optimal run included pH, 9; catalyst dosage, 1 g/L; irradiation time, 60 min; and C_MB, 2 mg/L, and the best removal efficiency of 98% was achieved during these conditions.

Bimetallic p-ZnO/n-CuO nanocomposite synthesized using Aegle marmelos leaf extract exhibits excellent visible-light-driven photocatalytic removal of 4-nitroaniline and methyl orange

In the current study, the photocatalytic activity of bimetallic ZnO-CuO hetero-nanocomposite was evaluated and compared with the monometallic ZnO and CuO nanoparticles using 4-nitroaniline (4-NA) and methyl orange (MO). Bimetallic ZnO-CuO hetero-nanocomposite, ZnO, and CuO nanostructure were synthesized utilizing leaf extract of Aegle marmelos and characterized by transmission electron microscopy, X-ray diffraction, and XPS. Benefiting from the p-n heterostructures formation, bimetallic ZnO-CuO hetero-nanocomposite exhibits an excellent photocatalytic activity against 4-NA as well as MO compared to pure ZnO and CuO. In particular, bimetallic ZnO-CuO hetero-nanocomposite expressed the highest photocatalytic activity by reducing 90% of 4-NA in 20 min and by degrading 96% of MO in 10 min, whereas 65% reduction of 4-NA in 30 min and 93% degradation of MO in 45 min was exhibited by CuO and 48% reduction of 4-NA in 30 min and 98% degradation of MO in 50 min was exhibited by ZnO. Moreover, bimetallic ZnO-CuO hetero-nanocomposite maintains excellent photocatalytic activity even after five cycles indicating its stability as photocatalyst and reusability. Based on the experimental findings, bimetallic ZnO-CuO hetero-nanocomposite could be used as a photocatalyst for wastewater treatment with excellent regeneration efficiency.

Photocatalytic Degradation of Orange G Dye by Using Bismuth Molybdate: Photocatalysis Optimization and Modeling via Definitive Screening Designs

In the current study, Bismuth molybdate was synthesized using simple co-precipitation procedure, and their characterization was carried out by various methods such as FT-IR, SEM, and P-XRD. Furthermore, the photocatalytic degradation of Orange G (ORG) dye using synthesized catalyst under visible light irradiation was studied. Response surface Method was used for the optimization of process variables and degradation kinetics evaluated by modeling of experimental data. Based on the experimental design outcomes, the first-order model was proven as a practical correlation between selected factors and response. Further ANOVA analysis has revealed that only two out of six factors have a significant effect on ORG degradation, however ORG concentration and irradiation time indicated the significant effects sequentially. Maximum ORG degradation of approximately 96% was achieved by keeping process parameters in range, such as 1 g L-1 loading of catalyst, 50 mg L-1 concentration of ORG, 1.4 mol L-1 concentration of H2O2 at pH 7 and a temperature of 30 °C. Kinetics of ORG degradation followed the pseudo first order, and almost complete degradation was achieved within 8 h. The effectiveness of the Bi2MoO6/H2O2 photo-Fenton system in degradation reactions is due to the higher number of photo-generated e- available on the catalyst surface as a result of their ability to inhibit recombination of e- and h+ pair.

Fabrication of a zinc oxide/alginate (ZnO/Alg) bionanocomposite for enhanced dye degradation and its optimization study

This paper studies a new response surface methodology (RSM) based on the central composite design (CCD) modeling method to optimize the photocatalytic degradation of methylene blue (MB) and methyl orange (MO) by using a synthesized ZnO/Alg bionanocomposite under UV irradiation. ZnO with different content of sodium alginate (Alg) (10, 20, and 30% by weight) has been synthesized by a one-step sol–gel method. Zinc oxide (ZnO) nanoparticles were impregnated on the alginate polymer. Various characterization techniques were used to describe the physical and chemical properties of each catalyst such as XRD, FTIR, UV-vis, PL, FESEM, Raman, and BET. The optimal catalyst for MB and MO photocatalytic degradation process was discussed mathematically as a function of catalyst dose, irradiation time, and MB and MO concentration, which was modeled by CCD-RSM based on a statistical model (quadratic regression) and an optimization process (ANOVA analysis). The photocatalytic degradation efficiency of 98% was achieved for the optimal conditions of a dye concentration of 20 mg L⁻¹, the catalyst dose of 0.34 g L⁻¹, and an irradiation time of 90 min at pH 6. The measurement result (R² = 0.9901) showed that the considered model is very suitable, and the selected CCD-RSM successfully optimized the photodegradation conditions of MB and MO.

Here, we reported the synthesis of ZnO/Alg bionanocomposite and analyzed photocatalytic degradation efficiency for MB and MO dyes under UV light. We also performed optimization studies using the RSM-CCD method and obtained 98% degradation efficiency.

Degradation of hexavalent chromium and methyl orange by the synergistic system of graphitic carbon nitride and electron beam irradiation

Hexavalent chromium (Cr(VI)) and methyl orange (MO) are highly toxic and difficult to treat. Electron beam irradiation (EB) can produce ·OH, H·, ·O₂^-, hydrated electron (e_aq^-) and other active substances, which have strong redox ability to pollutants. However, the penetration capacity of EB is limited (the penetration depth of water is 10 cm). Therefore, the photocatalytic method of graphitic carbon nitride (CN) was used as the synergistic method of EB in this project to degrade Cr(VI) and MO. The results showed that the maximum treatment efficiency of 100 mg L^-1 Cr(VI) and 50 mg L^-1 MO with liquid surface height of 5 cm was 95.0% and 99.1%, respectively, which was much higher than that of single photocatalytic method (39.5%, 23.4%) and EB (79.6%, 92.1%), and the efficiency of synergistic treatment was higher under acidic condition. When the liquid depth increased to 30 cm, the efficiency of synergistic system decreased by 14.7% and 15.2% for the degradation of Cr(VI) and MO, respectively, less than the single EB treatment (47.2%, 45.7%). Additionally, the performance of the morphology, the light absorption performance, and the separation of photogenerated electron-hole pairs of the CN were evaluated before and after the synergistic system. Lastly, the mechanism illustrates that the electron and thermal effects of EB, e_aq^-, photogenerated electrons played key roles for the Cr(VI) reduction, and the electron and thermal effects of EB, ·O₂^-, photogenerated holes played key roles for the MO degradation. This study provides a new opportunity for the synergistic system of photocatalyst and EB in the treatment of pollutants.

Catalytic behavior and antibacterial/antifungal activities of new MNPs/zeolite@alginate composite beads

In this paper, a new family of composite materials was prepared based on calcium alginate and metal nanoparticle-loaded zeolite omega. Different types of metal nanoparticles (MNPs), namely Cu, Co and Fe, were loaded onto zeolite omega to test the performance of the resulting metal/zeolite@alginate composites towards the catalytic reduction of methylene blue dye. To examine their application field as broadly as possible, these composite beads were also tested as antibacterial and antifungal agents against several types of bacteria. Several techniques such as XRD, XRF, FTIR, XPS, SEM and TGA were used to characterize the samples. The obtained results showed that all the composite bead samples were effective in the reduction of MB dye. The composite Co/Zeolite@ALG with relatively low Co nanoparticle (NP) content was selected as the best performing catalyst due to its reduction of MB dye being completely achieved in 3 min with a rate constant of 1.4 min^-1, which was attributed to its highly porous structure. The reuse tests conducted on the best-performing catalyst showed good results which persisted through five successive cycles. For antibacterial and antifungal activities, the Cu/Zeolite@ALG and Fe/Zeolite@ALG composites showed good activity with significant inhibition zones.

Cerium-, Europium- and Erbium-Modified ZnO and ZrO2 for Photocatalytic Water Treatment Applications: A Review

In the last decades photocatalysis has become one of the most employed technologies for the implementation of the so-called Advanced Oxidation Processes (AOPs) for the removal of harmful pollutants from wastewaters. The materials identified as the best photocatalysts are transition metal oxides, in which the band structure allows charge carrier separation upon solar irradiation. The photoinduced charge carrier can thus cause oxidative and reductive redox reactions at the surface, inducing the formation of the radical species able to initiate the AOPs. Despite the great advantages of this process (non-toxic, cheap and environmentally clean), the main drawback lies in the fact that the most efficient semiconductors are only able to absorb UV irradiation, which accounts for only 5% of the total solar irradiation at the Earth’s surface and not enough to generate the required amount of electron-hole pairs. On the other hand, many efforts have been devoted to the sensitization of wide band gap transition metal oxides to visible light, which represents a higher percentage (almost 45%) in the solar electromagnetic spectrum. Among all the strategies to sensitize transition metal oxides to visible irradiation, doping with lanthanides has been less explored. In this regard, lanthanides offer a unique electronic configuration, consisting in 4f orbitals shielded by a 5s5p external shell. This occurrence, coupled with the different occupation of the localized 4f orbitals would provide an astounding opportunity to tune these materials’ properties. In this review we will focus in depth on the modification of two promising photocatalytic transition metal oxides, namely ZnO and ZrO2, with cerium, europium and erbium atoms. The aim of the work is to provide a comprehensive overview of the influence of lanthanides on the structural, optical and electronic properties of the modified materials, emphasizing the effect of the different 4f orbital occupation in the three considered doping atoms. Moreover, a large portion of the discussion will be devoted to the structural-properties relationships evidencing the improved light absorption working mechanism of each system and the resulting enhanced photocatalytic performance in the abatement of contaminants in aqueous environments.