Optimum Conditions For Removal Research Articles

Innovative alginate-clay shell and magnetite-gelatin core composite for multifaceted contaminant removal: Cadmium, thiabendazole and bacterial adsorption from aqueous solutions.

In this study, a novel magnetic composite adsorbent with an alginate-chamotte clay outer layer and a gelatin-magnetite core was synthesised for effective contaminant removal from aqueous solutions. The alginate component ensures biocompatibility, chamotte clay enhances adsorption, gelatin provides mechanical strength, and magnetite enables easy recovery of the adsorbent. The composite material was characterised using Fourier-transform infrared, X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy-energy-dispersive X-ray analysis, micro-computed tomography, Brunauer-Emmett-Teller analysis and dynamic mechanical analysis techniques. Response surface methodology was employed to optimise cadmium and thiabendazole adsorption. Optimal conditions for cadmium removal were achieved at pH7 using 500mg of adsorbent, with a 30-min contact time and a 5mL sample volume. Additionally, thiabendazole adsorption was optimal at pH3, with a 65-min contact time. Thermodynamic and kinetic experiments revealed that both adsorption processes were spontaneous and endothermic and followed a pseudo-second-order model. Cadmium adsorption aligned with Langmuir isotherm , while thiabendazole adsorption followed Freundlich isotherm . The adsorbent also showed high antibacterial efficiency, effectively removing both Gram-positive S. aureus and Gram-negative E. coli, with adsorption capacities of 43.86mgg-1 for cadmium, 5.01mgg-1 for thiabendazole, 2.5×1010CFUg-1 for E. coli and 6.7×1010CFUg-1 for S. aureus. These results highlight the multifunctional potential of the adsorbent for wastewater treatment.

Selective extraction process of scandium from nickel laterite waste through hydrometallurgy.

Scandium (Sc) extraction from iron and aluminum waste is a promising technique for the recycling and valorization of laterite nickel ore waste. Iron and aluminum waste is one source of scandium during preparation of nickel and cobalt hydroxide by wet smelting of laterite nickel ore. The content of Sc is notably higher than that of the raw materials, as the element is enriched in the iron and aluminum waste. As the main element in the waste samples, Al exhibits significant interference in the selective separation of Sc. In this work, taking the production line for laterite nickel ore wet leaching as the research object, the trend and distribution of trace Sc were systematically analyzed. A series of leaching experiments was conducted under varied conditions of leaching pH (2.6-3.5), leaching time (0.5-2.0 h), volume of evaporated concentrated solution (0.2-1.0 L), mass of waste added (200-800 g), reaction temperature (240-260 °C), reaction time (0.5-1.5 h), H2SO4 addition amount (50-300 mL L-1) and (NH4)2SO4 addition amount (150-350 kg m-3). Experimental results revealed that the optimum leaching conditions were observed at a pH value of 3.0 and a leaching duration of 1 h. The optimum condition for evaporation and concentration was at 0.35 L, while the optimum conditions for impurity removal were at a waste mass of 300 g, a reaction temperature of 255 °C and a reaction time of 1 h. Under these optimum conditions, scandium content was approximately 14.67%. The product was identified as a complex salt of Sc through XRD, which could be converted to high-purity Sc2O3 after roasting.

Removal of Zn(II), Cu(II) and Pb(II) from Rainwater by White Bean Peel: Optimization by Response Surface Methodology

Potentially toxic elements (PTEs) have been found in high levels in rainwater, highlighting the importance of removing them when the water is intended for domestic use. In this work, white bean peel was evaluated as sorbent for the removal of a mixture of PTEs from rainwater, namely Zn(II), Cu(II) and Pb(II). A uniform experimental design was used to evaluate the sorption and to optimize the removal process by response surface methodology. The biosorbent reduced the PTEs concentration in the solution, and their removal increased with the increase of the initial concentration and with time. The removal of Cu(II) and Pb(II) was affected by the pH of the solution since, at pH 7.0 for Cu(II), and at pH 5.6 and 7.0 for Pb(II), a decrease occurred in the removal. The optimal conditions for removal, 6 h of contact time between the sorbent and the solution, were applied to rainwater samples spiked with the mixture of PTEs and resulted in removals of 30–90% for Zn(II), 11–78% for Cu(II), and 11–97% for Pb(II), generally lower than those expected by the models, 91% for Zn(II) and 52% for Cu(II), highlighting that the rainwater matrix interferes with the removal of PTEs by peel. However, the white bean peel may be an alternative as sorbent to reduce Zn(II), Cu(II), and Pb(II) concentrations in rainwater, since it is a natural and sustainable material.

Waste PET bottle-derived carbon for defluorination of fluoride-polluted water

ABSTRACT This study synthesises expanded graphite (EG) from graphitised carbon from waste polyethylene terephthalate (PET) bottles. The adsorbent material was characterised using FTIR, XRF, XRD, SEM, Raman Spectroscopy, and BET surface area analysis. The synthesised EG defluorinated wastewater, utilising response surface methodology (RSM) for experimental design and optimisation. XRD patterns confirmed the successful synthesis of graphite and EG, demonstrating structural modifications. Raman spectra indicated higher crystalline order in EG, with D and G band shifts and an increased ID/IG intensity ratio from 0.89–1.04. BET analysis revealed a specific surface area of 247.1 m²/g. . FTIR analysis showed abundant functional groups, particularly hydroxyl (-OH) and alkene (C = C). Batch adsorption experiments revealed that fluoride adsorption onto EG depended on pH, time, and initial fluoride concentration. Optimal conditions for fluoride removal, determined using RSM with central composite design (CCD), demonstrated a maximum fluoride removal rate of 97%. Isotherm data fitted both Langmuir and Freundlich model, and kinetics data aligned well with the pseudo-first-order model. ANOVA showed significant effects of contact time, pH, adsorbent dose, and initial fluoride concentration on removal efficiency. The model's R² value of 0.98 and lack of fit value of 0.1554 confirmed the quality of the second-order polynomial model. Optimal conditions for maximum fluoride removal efficiency of 97% were validated at 5 mg/L fluoride concentration, pH 4, adsorbent dose of 5 g/L, and a contact time of 30 min. Therefore, the present study demonstrated efficient fluoride-polluted water treatment using waste-derived EG.

Chemical Precipitation removal of Boron in Synthetic Wastewater using Microwave Heating

Objectives : The objective of this study is to investigate the potential for the removal of boron(B) from synthetic wastewater through chemical precipitation using microwave heating to identify the optimal conditions for the removal of boron.Methods : Synthetic wastewater was prepared using boric acid(H3BO3) and distilled water. The range of variables that exert an influence on boron removal included the initial pH 3-13, the calcium hydroxide(Ca(OH)2) dosage of 0.5-10 g per 30 mL(17–333 g/L), and the boron concentration of 100-1,500 mg/L. A face-centered design in response surface method was employed to identify the optimal conditions for boron removal in a continuous scale and to ascertain the interaction of the factors.Results and Discussion : In discontinuous conditions, the maximum removal efficiency was observed at initial pH 3, Ca(OH)2 of 2 g, and the boron concentration of 1,500 mg/L. As the pH value decreased, the removal of boron increased. The greatest removal efficiency was observed when the dosage of Ca(OH)2 was 2-5 g. It was also found that the higher the concentration of boron, the greater the removal efficiency. In the continuous scale, the optimal conditions for boron removal were identified as initial pH 3.3, the dosage of 6.2 g Ca(OH)2, and the boron concentration of 1,500 mg/L, with the removal efficiency of 93%. All independent variables exerted a statistically significant influence on chemical precipitation removal(p<0.05). In comparison to pH(p=0.047), boron concentration(p<0.001) and Ca(OH)2 dosage(p<0.001) demonstrated a more pronounced impact on boron removal. The interaction between boron concentration and Ca(OH)2 dosage was also identified as statistically significant(p<0.001).Conclusion : Chemical precipitation using microwave heating was effective in removal of boron from wastewater, and the optimal conditions in continuous scale through response surface analysis were initial pH 3.3, boron concentration 1,500 mg/L, and Ca(OH)2 dosage 6.2 g(207 g/L).

The Nitrogen Removal Characteristics of a Novel Salt-Tolerant Bacterium, Enterobacter quasihormaechei DGFC5, Isolated from Municipal Sludge.

A novel bacterial strain, Enterobacter quasihormaechei DGFC5, was isolated from a municipal sewage disposal system. It efficiently removed ammonium, nitrate, and nitrite under conditions of 5% salinity, without intermediate accumulation. Provided with a mixed nitrogen source, DGFC5 showed a higher utilization priority for NH4+-N. Whole-genome sequencing and nitrogen balance experiments revealed that DGFC5 can simultaneously consume NH4+-N in the liquid phase through assimilation and heterotrophic nitrification, and effectively remove nitrate via aerobic denitrification and dissimilatory reduction reactions. Single-factor experiments were conducted to determine the optimal nitrogen removal conditions, which were as follows: a carbon-to-nitrogen ratio of 15, a shaking speed of 200 rpm, a pH of 7, C4H4Na2O4 as the carbon source, and a temperature of 30 °C. DGFC5 showed efficient nitrogen purification capabilities under a wide range of environmental conditions, indicating its potential for disposing of nitrogenous wastewater with high salinity.

Investigating dye adsorption: The role of surface-modified montmorillonite nanoclay in kinetics, isotherms, and thermodynamics

Abstract The study presents a straightforward, eco-friendly method for removing toxic dyes, such as methylene blue (MB) and acid red (AR), from aqueous solutions through solid-phase extraction using adsorption on surface-modified montmorillonite nanoclay. The nanoclay, containing 25–30 wt% methyl dihydroxyethyl hydrogenated tallow ammonium (MM-MDH nanoclay), functions as the environmentally benign adsorbent. The physical properties of MM-MDH nanoclay were characterized utilizing scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and surface area analysis. Optimal conditions for dye removal, including solution pH, nanoclay dosage, contact time, solution temperature, and ionic strength, were systematically investigated. Experimental results demonstrated that MM-MDH nanoclay effectively removed the majority of dyes within 90 min. Isotherm data indicated an adsorption capacity of 34.33 mg/g for AR dye and 20.19 mg/g for MB dye under optimal conditions. The adsorption process was analyzed kinetically and thermodynamically, revealing that the pseudo-second-order kinetic model accurately described the adsorption behavior. Thermodynamic analysis confirmed that the process was spontaneous and exothermic for AR dye and spontaneous and endothermic for MB dye. The effectiveness of MM-MDH nanoclay was further validated by removing dyes from three different real samples, demonstrating high performance in dye removal over four consecutive cycles.

A novel metal-free perylene-functionalized graphite adsorbent for efficient antibiotic removal from wastewater.

Adsorption remains a widely utilized and effective technique for removing chemical contaminants from polluted water, and novel adsorbents are currently in the process of being developed. The presence of antibiotics residues in aqueous effluents is a potential concern due to their potential adverse effects on living organisms. In this work, perylene tetracarboxylic acid-functionalized expanded graphite (PTCA-EG) was synthesized as a metal-free adsorbent and its potential for efficient treatment of contaminated wastewater with cefalexin (CLX) antibiotic was studied. The experimental variables were modeled and optimized using central composite design (CCD) and response surface methodology (RSM) to maximize adsorption efficiency. In this regard, the contact time of 20min, solution pH of 7.0, adsorbent dosage of 18mg, and initial CLX concentration of 45mg L-1 were found to be the optimum conditions for adsorptive removal of CLX with a maximum efficiency of 99 ± 1.21%. In addition, the adsorption equilibrium data were well analyzed with isotherm, kinetic, and thermodynamic studies. The isotherm results revealed the adsorption process was favorable and took place on the heterogeneous surface. Moreover, the Langmuir maximum adsorption capacity (Qmax) was determined as 220.7mgg-1. Also, thermodynamic parameters revealed the spontaneity and endothermic nature of the adsorption process. The reusability studies demonstrated that the spent PTCA-EG can be easily regenerated through NaOH solution (0.01mol L-1) and reused for six cycles without any significant decrease in its adsorption efficiency. Also, the PTCA-EG showed excellent behavior in adsorptive removal of CLX in real water samples including river water (96.61 ± 1.82%) and hospital effluents (91.91 ± 3.41-93.69 ± 3.06%).

Mitigating the challenges of textile wastewater treatment in Saudi Arabia utilizing electrocoagulation process: Optimization of operating parameters

The increasing importance of treating industrial effluents for environmental and public health protection has necessitated reliable and economical treatment methods capable of meeting stringent effluent quality standards. This study aimed to evaluate the effectiveness of the electrocoagulation (EC) process using iron electrodes for treating real textile wastewater by removing total solids (TS), COD, colour, and turbidity. Various operating parameters, including treatment time, initial pH, current density, stirring speed, and inter-electrode spacing (IES), were investigated to optimize removal efficiency. The results demonstrated that the optimal conditions for maximum pollutant removal were achieved at a treatment time of 60 minutes, a current density of 6.2 mA/cm², a solution pH of 8-8.5, a stirring speed of 150 rpm, and an IES of 5 cm. Under these conditions, the removal efficiencies reached 79.2% for TS, 92.7% for COD, 88.9% for turbidity, and 98.7% for colour. The findings of this research indicate that the EC process is a simple, quick, and economically viable method for effectively removing pollutants from textile wastewater. Additionally, it is recommended that a coupled treatment unit, such as filtration or adsorption, be employed following the EC process to enhance pollutant removal. Saudi Arabia’s Vision 2030 aims to address environmental pollution from industrial wastewater, including textile wastewater, highlighting the importance of balancing industrial growth with environmental stewardship. Present study offers the first thorough analysis of textile wastewater treatment utilizing EC process in the region, enhancing understanding of effective strategies for sustainability and compliance with effluent quality standards.

Efficient removal of crystal violet and acid red 88 dyes from aqueous environments using easily synthesized copper ferrite nanoparticles

This study details the synthesis and application of magnetic copper ferrite (CuFe2O4) nanoparticles for the efficient removal of acid red 88 and crystal violet dyes from aqueous solutions. Utilizing a combustion method, nanoparticles were synthesized with succinic and malic acids as fuels, yielding samples with crystallite sizes of 28.54 ± 0.90 nm for the sample synthesized with malic acid and 19.79 ± 0.75 nm for the sample synthesized with succinic acid. Optimum removal conditions were found at a pH of 2 for acid red 88 and pH 10 for crystal violet, with a contact time of 80 min and an adsorbent dosage of 0.05 g in a 100 mL solution. Under these conditions, the sample synthesized using succinic acid achieved sorptive capacities of 452.49 mg/g for acid red 88 and 446.43 mg/g for crystal violet, while the sample synthesized using malic acid reached 408.16 mg/g and 374.53 mg/g, respectively. Both adsorption processes followed the pseudo-second-order kinetic model and aligned with the Langmuir isotherm. Thermodynamic analysis confirmed the process as exothermic and spontaneous. Practical trials demonstrated removal efficiencies above 95% for both dyes in real wastewater samples, underscoring the method’s practical potential in water purification applications.

Modification of nickel ferrite nanoparticles by sodium docusate surfactant for superior crystal violet dye removal from aqueous solutions

In this study, nickel ferrite (NiFe2O4) nanoparticles were synthesized using the Pechini sol-gel method and modified with sodium docusate surfactant. The modified nanoparticles showed an enhanced adsorption capacity of 384.62 mg/g for crystal violet dye, compared to 237.53 mg/g for unmodified NiFe2O4. Characterization was performed using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), and scanning electron microscopy (SEM) techniques. The adsorption process was spontaneous, exothermic, and followed the Langmuir isotherm and pseudo-second-order kinetic model. Optimal conditions for maximum dye removal were achieved at pH 10, 50 min, and 298 K. Additionally, the synthesized adsorbents demonstrated excellent regeneration and reusability over five adsorption-desorption cycles with minimal efficiency loss.

Response Surface Methodology: A Review on Optimization of Adsorption Studies

Herein, we reviewed response surface methodology (RSM), a powerful statistical tool widely used in optimizing adsorption processes to remove synthetic dyes, toxic heavy metals, and phenols from wastewater. The widely used RSM models during optimization are the central composite design and Box-Behnken, which are second-order polynomial models. The models give a predictive insight into the number of experimental runs to be carried out. Furthermore, an in-depth overview of RSM and its application in optimizing various adsorption parameters, such as adsorbent dosage, initial pollutant concentration, contact time, and pH is discussed. In addition, RSM enables researchers to efficiently determine the optimal conditions for maximum pollutant removal. Lastly, the findings of this research highlight the potential of RSM as a valuable tool for optimizing adsorption processes and contributing to sustainable water treatment technologies.

Preparation and characterisation of chitosan/bacterial Escherichia coli biocomposite for malachite green dye removal: modeling and optimisation of the adsorption process

ABSTRACT Herein, a new biocomposite was obtained by loading a bacterial suspension of Escherichia coli onto a chitosan matrix to produce a unique biocomposite (chitosan – E. coli) with effective properties for biosorption of malachite green dye from water. The physicochemical characteristics of the chitosan – E. coli biocomposite were studied by employing XRD, FTIR, FESEM-EDX and pHpzc. The optimisation of biosorption conditions was achieved using a Box-Behnken Design (RSM-BBD) to assess the effect of variables on the dye removal: biocomposite dose (0.02–0.1 g/100 mL), pH (4–8) and contact time (10–300 min). The optimal conditions for dye removal (84.3%) were achieved with a chitosan – E. coli dose of 0.1 g/100 mL, and a contact time of 160 minutes with a pH of 8. The equilibrium and kinetic experimental findings show the biosorption of malachite green dye by chitosan – E. coli follows the Langmuir and pseudo-second-order models, respectively. The maximum dye adsorption capacity (q max ) of malachite green for the chitosan – E. coli biocomposite was 164.7 mg/g, where the dye adsorption mechanism was attributed to several effects such as hydrogen bonding, n-π interactions, and electrostatic attraction. Thermodynamic analysis indicated that the biosorption process was spontaneous and endothermic, with a positive enthalpy change (ΔH° = 40.9 kJ/mol) and a negative Gibbs free energy (ΔG°) at all tested temperatures. The biocomposite chitosan – E. coli adsorbent exhibits favourable cationic dye adsorption that is anticipated to have utility for remediation of dye effluent in industrial wastewater.

Enhanced catalytic degradation of acetaminophen using magnesium oxide-infused clay with ultrasonic activation of hydrogen peroxide

In this study, clay modified with magnesium oxide (MgO) was used as a catalyst for the degradation of acetaminophen in wastewater, activated by hydrogen peroxide (H2O2) and ultrasonic waves. Characterization of the Clay-MgO catalyst was conducted using TGA, XRD, BET, SEM, FTIR, XRF, and EDX, revealing functional groups capable of activating H2O2. The crystalline catalyst, synthesized at 500 °C, had a surface area of 30 m2/g. Optimal conditions for acetaminophen removal, achieving 75 % efficiency, were pH 8, 3 g/L catalyst, 0.2 mL/100 mL H2O2, and 60 min of contact time. In distilled water, mineralization of acetaminophen was 42 %, while actual wastewater showed 18 %. Hydroxyl radicals played a significant role in the degradation process. The catalyst was tested for reuse up to six times and maintained a high efficiency of over 53 % in five stages. Radical scavenger studies confirmed the importance of hydroxyl radicals in the degradation kinetics, which followed pseudo-first-order (R2 > 0.96) and Langmuir-Hinshelwood (R2 = 0.95) models. The catalyst also demonstrated efficient acetaminophen removal in complex solutions, including seawater. This MgO-modified clay shows promise as an effective catalyst for the degradation of pharmaceutical pollutants through hydrogen peroxide activation, maintaining stability and reusability across multiple cycles.

Separation of cerium from solution by oxidative precipitation with hydrogen peroxide: The reaction mechanism

Cerium removal from solution via oxidative precipitation with hydrogen peroxide was investigated in a batch reactor to identify optimum conditions for maximum Ce removal. Tests were performed under ambient temperature at pH 2, 3, 4 and 5, using the exact stoichiometric requirement and 30 % and 50 % excess, respectively. It was found that, unlike the usual direct Ce(OH)4 formation presented in the literature for most oxidants, the reaction with hydrogen peroxide proceeded via a metastable ceric hydroxide, with conversion rates increased by increasing temperature. Standard free energies of reaction were calculated for both routes. To better understand the process, the oxidation of Ce(III) to Ce(IV) and the precipitation of Ce(OH)4 were studied separately via a decoupled approach at low pH and reaction mechanisms for each process were proposed. The Ce(III) oxidation reaction was identified as the rate-limiting step, whereas Ce(IV) precipitation was fast and quantitative. In the pH range of 3–5, Ce removal extents varied between 80 and 95 %, depending on the hydrogen peroxide excess. Following the Ce removal step via oxidative precipitation, it was found that a 2 h ageing stage at 80 °C and pH 2.5 was required to complete the transition of cerium hydroxy-peroxide to the more stable ceric hydroxide and decompose any residual H2O2.

Resource Recovery from Abandoned Mine Drainage Galleries via Ion Exchange: A Case Study from Freiberg Mining Area, Germany

The discharge of metal-loaded mining-influenced waters can significantly pollute downstream water bodies for many kilometers. Addressing this issue at the earliest discharge point is crucial to prevent further contamination of the natural environment. Additionally, recovering metals from these discharges and other sources of contamination can reduce the environmental impacts of mining and support the circular economy by providing secondary raw materials. This study focused on optimizing zinc recovery from mining-influenced water in the Freiberg mining region in Germany, where significant loads of zinc are released into the Elbe River. By employing pretreatment techniques, conducting 100 mL scale ion-exchange column experiments, and refining the regeneration process, we aimed to identify optimal conditions for efficient zinc removal and recovery. Initial tests showed that aminophosphonic functionalized TP 260 resin had a high affinity for aluminum, occupying 93% of the resin’s capacity, while zinc capacity was limited to 0.2 eq/L. To improve zinc recovery, selective precipitation of aluminum at pH 6.0 was introduced as a pretreatment step. This significantly increased the zinc loading capacity of the resin to 1 eq/L. Under optimal conditions, a concentrated zinc solution of 18.5 g/L was obtained with 100% recovery. Sulfuric acid proved more effective than hydrochloric acid in eluting zinc from the resin. Further analysis using SEM-EDX revealed residual acid on the resin, indicating a need for additional study on long-term resin performance and capacity variation. The research also highlighted the environmental impact of the Freiberg mining area, where three drainage galleries currently contribute nearly 85 tons of zinc annually to the Elbe River. This study underscores the feasibility of efficient zinc recovery from these point sources of pollution using advanced ion-exchange processes, contributing to circular economy efforts and environmental conservation.

Effect of hydraulic retention time and treated urban wastewater ratio on progressive adaptation of an inoculated microalgae in membrane photobioreactors

Currently, there is a growing concern about water scarcity. The rising demand for wastewater treatment systems that facilitate the reuse of wastewater has resulted in a focus on the use of microalgae in sustainable treatments. These methods not only eliminate nutrients from the wastewater but also produce biomass that can be used to obtain high-value products. This study aimed to observe the effect of different hydraulic retention times (HRTs) and treated urban wastewater (TUWW) percentages on the growth of microalgae biomass and nutrient consumption in membrane photobioreactors. Microalgae biomass growth increases with HRT regardless of the percentage of TUWW. Biomass concentration stabilises at between 40% and 60% TUWW but significantly increases when 100% TUWW is used, resulting in the highest biomass concentrations. As HRT increases, ammonium and total nitrogen consumption also rise. A positive trend in ammonium consumption was observed with increasing TUWW, reaching its peak with 100% TUWW. The optimal conditions for biomass growth and nutrient removal are achieved with a 7-day HRT and 100% TUWW as influent, which was confirmed as optimal with the response surface methodology.

Porous biochar supported PET plastic waste MOF heterostructure as a novel, efficient and recyclable catalyst for acetaminophen degradation

Herein, the innovative hybrid photocatalyst PET-based Zn-MOF on orange peel biochar (BC)(PZM/BC) was designed and synthesized via the hydrothermal method. Electrochemical methods have been used to demonstrate the action of the PET-MOF in the PZM/BC photocatalyst as a medium for electron transfer. The latter involved the synthesis of a zinc-containing metal–organic framework (MOF) in which the linkers were derived from the depolymerization of polyethylene terephthalate (PET) originating from plastic wastes. According to research, the catalytic reactions are sped up when porous BC and linker PET are assimilated into PZM/BC photocatalyst hetero-junction. Furthermore, BC stored electrons under light and released these electrons under dark conditions. When BC was combined with PET-MOF, the electrons on the biochar activated the catalytic redox activity of acetaminophen. Additionally, it lowers the reassimilation rate due to the combined meshed nanostructures and functionality of PET-MOF and PZM/BC. UV–Vis DRS, Mott-Schottky, Photoluminescence(PL), and Electrochemical Impedance spectra(EIS) results showed that the PZM/BC exhibited efficient spatial separation and transportation of photogenerated charge carriers and exhibited superior photocatalytic ability. Electron spin resonance(ESR) analysis confirmed that ⋅OH and h+ were the predominant radical species responsible for the degradation of acetaminophen(ACT). The optimum conditions for ACT removal were observed at pH 6.07, with a PZM/BC dosage of 0.1 g L−1, and an initial ACT concentration of 50 mg L−1, highlighting the pivotal role of the PZM/BC system in ACT degradation. Furthermore, potential photocatalytic degradation pathways of ACT were inferred renders on the identified intermediates which are responsible for the degradation of refractory intermediates. Regeneration trials were carried out to assess the stability of the photocatalyst. Additionally, the degraded intermediates generated during the degradation processes were examined, providing a comprehensive elucidation of the degradation mechanism.Graphical

Elimination of malachite green by modified Fenton like process. Application of Box Behnken design

<p class="AbstractText" style="margin-bottom:3.0pt;"><span style="letter-spacing:-.1pt;" lang="EN-US">The aim of this work was to investigate an advanced oxidation process for removing malachite green from aqueous solutions using a modified Fenton-like process. An experimental Box-Behnken design was applied to determine the optimal conditions by examining the effects of catalyst concentration ([Fe<sup>2+</sup>]), oxidant concentration ([K<sub>2</sub>S<sub>2</sub>O<sub>8</sub>]), and stirring speed. The analysis of variance (ANOVA) indicated that oxidant concentration was the most significant factor, with a p-value of 0.001, while catalyst concentration, the quadratic term of the oxidant, and the interaction between catalyst concentration and stirring speed were also significant. The optimal conditions for maximum dye removal were found to be a catalyst concentration of 3.5 ppm, an oxidant concentration of 3.07 ppm, and a stirring speed of 200 rpm, achieving a theoretical degradation yield of 100% and an experimental yield of 98%. This agreement validates the model and the importance of the optimized parameters. Additionally, degradation kinetics studies in various natural waters revealed that oxidation efficiency followed this order: Distilled water (98%) > Seawater ≈ Industrial water (88.97%) > Source water (85.57%) > Mineral water (80.52%).</span></p>

Selenocyanate removal using combined system of TiO2- photocatalysis and Fe(III)/SiO2 adsorption {UV-TiO2/[Fe(III)/SiO2]}: Complex destruction and simultaneous selenium species adsorption

Selenocyanate (SeCN‾) species, commonly found in industrial effluents from crude oil refineries and mining operations, present substantial health risks to humans and animals. This study investigates the treatment of selenocyanate-contaminated streams using a combination of TiO2 photocatalysis and Fe(III)/SiO2 binary oxide adsorption {UV-TiO2/[Fe(III)/SiO2]}. The Fe(III)/SiO2 binary oxide was synthesized and characterized using X-ray diffraction (XRD) and Fourier Transform Infrared (FTIR) spectroscopy. XRD analysis revealed non-crystalline Fe-oxide phases, while FTIR indicated the presence of various Fe and O functional groups on the Fe(III)/SiO2 surface. Adsorption studies using Fe(III)/SiO2 showed its selenocyanate uptake capacity ∼ 2.1 mg/g, with the respective data closely aligning with the Langmuir isotherm model. This Fe(III)/SiO2 adsorption feature was successfully combined in the {UV-TiO2/[Fe(III)/SiO2]} system in which the hydroxyl radicals (●OH) generated by the UV-TiO2 facilitated the breakdown of the selenocyanate complex, while the resulting selenite and selenate were simultaneously adsorbed by the Fe(III)/SiO2 within a 240-min reaction time. A mathematical model developed using a face-centered central composite design-response surface methodology (FCD-RSM) showed significant predictive capability with an insignificant lack of fit. Optimal conditions for selenium removal were determined to be 20 mg/L selenocyanate, 1 g/L TiO2, and 1 g/L Fe(III)/SiO2, at pH 5, within a 240-min reaction time. Kinetic analysis demonstrated that selenocyanate degradation followed pseudo-first-order kinetics, while total selenium removal adhered to pseudo-second-order kinetics, confirming the proposed selenium species removal mechanism. Overall, this integrated approach offers a promising solution for effective selenocyanate remediation in industrial wastewater.