Dose Concentration Research Articles

Copper-PANI-graphite HB2 composite for eco-friendly efficient degradation of textile dyes: Advancements in wastewater treatment enhanced by solar radiation

This research aimed to assess the potential of Cu50PANI@UG composite for sunlight drive photocatalytic dye degradation, targeting specifically Thymol Blue (TB) and Black NT (BNT) dyes and their mixture (DM). The Cu50PANI@UG composite was successfully synthesized via electropolymerization in acetonitrile/sulfuric acid mixture under atmospheric conditions. Photocatalytic experiments were conducted by exposing aqueous dye solutions to sunlight. N,N-dimethyl-p-nitrosoaniline (RNO) served as a molecular probe for detecting hydroxyl radicals (•OH). Additionally, experiments capturing free radicals were performed to identify active components, with a concomitant proposal of plausible degradation reaction mechanism for the Photo-Fenton-Like degradation into the Cu50PANI@UG composite + H2O2 + hv reaction system. Various operating parameters affecting dye degradation were evaluated, including catalyst dosage (from 0.27 to 0.67 g L−1), H2O2 concentration (from 16 to 64 mM), pH (from 3.0 to 9.0), and dye concentration (from 25 to 100 mg L−1). Optimization of key parameters such as pH, catalyst dosage, and H2O2 concentration was conducted. The highest degradation efficiency, ca. 100% of DM dye, was achieved within 35 min under optimized conditions, using Cu50PANI@UG composite as a catalytic precursor. These conditions were determined as follows: Catalyst dosage = 0.67 g L−1, pH = 3.0–6.0, H2O2 = 32–64 mM, and irradiation time of 35 min. The degradation percentage under the Response Surface Methodology (RSM) was utilized as a statistical tool to correlate influential parameters. Four consecutive reusability trials were performed to assess catalyst stability.

The PDINH decorated NH2-UiO-67 MOF for promoted photocatalytic Cr(VI) reduction: Performance, and mechanism

A series of composite materials comprising NH₂-UiO-67 metal-organic framework (MOF) and highly π-conjugated 3,4,9,10-perylenetetracarboxylic diimide (PDINH) was synthesized via a facile ball-milling process. These hetero-conjugated MOFs, denoted as PNU-67(X) with varying amounts of PDINH (X = 0.5 %, 1 %, 2 %, and 3 % wt), were evaluated for their photoreduction of Cr(VI) to Cr(III) under visible light irradiation. Systematic investigations revealed a direct correlation between increasing PDINH content and enhancing the conductivity of the MOFs. Additionally, the incorporation of PDINH motifs significantly improved CO₂ capture capability by increasing charge transfer, charge separation, and light absorption. To elucidate the impact of various factors on the photocatalytic performance of PNU-67(3) in Cr(VI) remediation, a comprehensive study was conducted. These factors included pH, initial Cr(VI) concentration, catalyst dosage, scavengers, and scavenger concentration. Notably, PNU-67(3) (5 mg/L) demonstrated 100 % photoreduction efficiency within 35 min, highlighting its potential application in catalyst loading and efficiency compared to other reported UiO-type MOFs. Furthermore, the composites exhibited exceptional stability and reproducibility throughout multiple experimental cycles. Overall, this research presents a promising avenue for constructing heterojunction photocatalysts by integrating MOFs and organic PDINH molecules, offering a viable solution for wastewater remediation.

Degradation of tetracycline in water using hydrogen peroxide activated by soybean residue-derived magnetic biochar

Tetracyclines (TCs) are the second most commonly used antibiotics worldwide, utilized both in medical treatments and animal husbandry. Although effective against various infectious diseases, TC residues persist in the environment and contribute to the emergence of antibiotic-resistant pathogens, posing significant risks to human health. This study employed the heterogeneous Fenton process to degrade TC using soybean residue-derived magnetic biochar (Fe-SoyB) as the catalyst. The Fe-SoyB sample was characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and superconducting quantum interference device (SQUID) techniques. The effects of key parameters, including pH, H2O2 concentration, catalyst dosage, and initial TC concentration, on TC degradation were investigated. The results indicated that the TC removal efficiency decreased with increasing initial TC concentration, while it was improved with higher H2O2 concentrations and greater catalyst dosages. The optimal conditions for the Fenton-like process were determined to a pH of 3, a H2O2 concentration of 245 mmol/L, an initial TC concentration of 800 mg/L, and a catalyst dosage of 0.75 g/L, achieving a removal efficiency of 90% after 150 min. Additionally, the TC removal efficiency of the Fe-SoyB system varied significantly across different water matrices, with 87.1% for deionized water, 78.5% for tap water, and 72.5% for river water. The catalyst demonstrated notable stability, maintaining a TC removal efficiency of 79.7% after three cycles of use. Overall, Fe-SoyB shows promise as a cost-effective catalyst for the elimination of organic pollutants in aqueous solutions.

Fabrication of a novel magnetic carbon nanotube coated with polydopamine modified with EDTA for removing Cd2+ and Pb2+ ions from an aqueous solution

This work demonstrates the preparation of a new, effective, and reusable magnetic adsorbent by functionalizing dopamine with ethylenediaminetetraacetic dianhydride and polymerizing it on the surface of magnetic carbon nanotubes (EDTA@PD-CNT/Fe3O4). The adsorbent was analyzed using XRD, FT-IR, Zeta potential, FE-SEM, EDX, BET, TGA, DTA, and VSM. The synthesized adsorbent was used to remove lead and cadmium ions from aqueous solution. The adsorption process was improved by optimizing key parameters such as pH, adsorbent dosage, contact time, and ion concentration. For both ions, the thermodynamic data of the processes and adsorption kinetics were examined. Analyzing the experimental data revealed that the Langmuir isotherm was the most appropriate model, and the examination of adsorption kinetics showed a pseudo-second-order equation. The adsorption process by the EDTA@PD-CNT/Fe3O4 adsorbent was spontaneous and endothermic, according to the thermodynamic data, for Cd2+ and Pb2+, the highest adsorption capacities were found to be 204.54 mg g−1 and 376.48 mg g−1, respectively.

Research on wax removal and prevention technology of White Wolf City oil well

Abstract Oil well wax removal technology is an important subject in the process of oil field exploitation. This paper analyzes the mechanism and characteristics of wax formation in oil Wells by measuring the amount of wax in crude oil in Baiwolcheng oil area. When the waxy component, which usually exists in liquid form, is accompanied by crude oil from underground to the ground, the waxy crystal precipitates and deposits in the inner wall of oil pipe due to the gradual decrease of the temperature of crude oil. The phenomenon of paraffin formation, paraffin formation process and paraffin formation law of oil well are studied, and chemical paraffin removal and anti-wax technology is determined as the main research object, evaluation and optimization of paraffin removal and anti-wax agent, and determination of dosage concentration and dosage.

Fluoride Removal in Water Using Kaolin and Eggshell Powder Blend Adsorbents

Fluoride contamination in water has emerged as a significant global concern due to its adverse health effects when consumed in excess. This study is focused on developing an eco-friendly, cost-effective adsorbent for fluoride removal using eggshells and kaolin. Adsorbent blends were prepared by mixing kaolin and eggshell powder in six different ratios, namely; 100:0, 80:20, 65:35, 50:50, 35:65, and 20:80. Cylindrical-shaped pellets were produced from each of the blends and subjected to the thermal treatment at 950 ◦C. Fluoride adsorption capacities of the pellets were investigated at different pH conditions (from pH 2 to pH 10) for a 5 mg/L fluoride solution with 1 g of adsorbent dosage and 60 min of contact time. Pellets with a 50:50 ratio (CKE3) were found to be the most effective adsorbent considering the adsorption capacity and stability at all the studied pH conditions. At pH 6, CKE3 showed an adsorption capacity of 0.06 mg/g compared to 0.02 mg/g of kaolin-only pellets. XRD, TGA-DSC, EDX and SEM analysis were used to characterize the adsorbent. XRD analysis showed that the raw adsorbent contained phases of CaCO3 and kaolinite, whereas the calcined material comprised Ca(OH)2 and metakaolinite. Batch experiments were carried out with CKE3 for adsorbent dosage, pH, contact time, and initial fluoride concentration. An adsorbent dosage of 4 g was capable of resulting in a 53% removal of fluoride for a 5 mg/L solution after 60 min of contact time. Pseudo-first-order and pseudo-second-order kinetic models were applied in the study, and pseudo-second-order exhibited the best fit. The isotherm data were studied for Langmuir and Freundlich models, and the results were satisfactorily fitted with Langmuir isotherm.

Experimental and Theoretical Studies on the Adsorption of Bromocresol Green from Aqueous Solution Using Cucumber Straw Biochar

Biochar prepared from crop straw is an economical method for adsorbing bromocresol green (BCG) from textile industrial wastewater. However, there is limited research on the adsorption mechanism of biochar for the removal of BCG. This study utilized cucumber straw as raw material to prepare biochar with good adsorption potential and characterized its physicochemical properties. Through adsorption experiments, the effects of solution pH, biochar dosage, and initial dye concentration on adsorption performance were examined. The adsorption mechanism of cucumber straw biochar (CBC) for BCG was elucidated at the molecular level using adsorption kinetics, adsorption isotherm models, and density functional theory (DFT) calculations. Results show that the specific surface area of the CBC is 101.58 m2/g, and it has a high degree of carbonization, similar to the structure of graphite crystals. The presence of aromatic rings, –OH groups, and –COOH groups in CBC provides abundant adsorption sites for BCG. The adsorption process of CBC for BCG is influenced by both physical and chemical adsorption, and can be described by the Langmuir isotherm model, indicating a monolayer adsorption process. The theoretical maximum monolayer adsorption capacity (qm) of BCG at 298 K was calculated to be 99.18 mg/g. DFT calculations reveal interactions between BCG and CBC involving electrostatic interactions, van der Waals forces, halogen–π interactions, π–π interactions, and hydrogen bonds. Additionally, the interaction of hydrogen bonds between BCG and the –COOH group of biochar is stronger than that between BCG and the –OH group. These findings provide valuable insights into the preparation and application of efficient organic dye adsorbents.

A chemometric approach using I-optimal design for optimising Pb(II) removal using bentonite-chitosan composites and beads

This paper reports adsorption studies of Pb(II) ions onto Bentonite-Chitosan (Bt-Ch) composites or beads when using an I-optimal design experiment approach. Three adsorption factors (pH, adsorbent dosage, and initial concentration) were optimised whilst simultaneously investigating multiple adsorbents. The Bt-Ch composites and beads (type A and B) adsorbents were made using weight ratios 90%/10% and differed characteristically due to their preparation methods of solution blending and precipitation, respectively. A batch procedure was used for adsorption experiments, and the amounts of Pb(II) ions (adsorbed onto Bt-Ch composites/beads) were analysed using inductively coupled plasma optical emission spectrometry (ICP-OES). Adsorption experimental parameters were analysed and optimised by using a response surface method (I-optimal design) generated from Design-Expert® 13.0 software. The main achievements of this study were to intensify the understanding and application of I-optimal experimental designs, which allow simultaneous determination of adsorption capacities and efficiencies across multiple adsorbents in an economical manner. A reduced quadratic model provided the best fit for the experimental data and exhibited minimal deviation between predicted and experimental values. This was evidenced by the very small covariance (CV) values of 1.81% and 1.33% observed for adsorption capacity and adsorption efficiency, respectively, also suggesting high reproducibility. It was observed that the adsorption factors studied (pH, adsorbent dose, and initial concentration) have a more pronounced effect on the adsorption capacity (F-value = 714.37) compared to adsorption efficiency (F-value = 140.62). Adsorbent dosage was found to have the greatest effect on adsorption capacity, while the initial pH of Pb(II) solution had the greatest effect on adsorption efficiency. Under optimal conditions, the adsorption capacities of beads-A (73.2 mg/g) and beads-B (77.6 mg/g) were found to be higher than that of the corresponding composite (51.7 mg/g). Whilst the optimum adsorption efficiency values for all three adsorbents were ∼100% (with ranges of pH 2–5, initial concentrations 50–200 mg/L, and adsorbent dosage 0.05–0.5 mg). The desirability indexes for the optimised conditions for these respective responses (and each adsorbent) were found to be within the ranges of 0.892–0.974 and 0.945–0.967 for adsorption capacity and adsorption efficiency, respectively. These high desirability index values for both responses indicate that the optimised conditions lead to very good performance for both measures. The information obtained in this study provides detailed understanding of the adsorption phenomena of the adsorbents studied. It gives confidence in the use of I-optimal designs to be applied as a chemometric tool for the specific adsorbents studied herein and others.

Fluoride Removal from Aqueous Solutions by Using Super-Adsorbents of Chitosan/Orange Peels/Activated Carbon@MgO: Synthesis, Characterization, and Adsorption Evaluation

Exposure to excessive concentrations of fluoride in potable water is harmful to human health; therefore, its limitation is deemed necessary. Among the commonly applied technologies, adsorption is selected, as it is a highly effective, simple, and economically efficient treatment. In the present study, several combinations of chitosan (CS), orange peels (OP), activated carbon (AC), and MgO were synthesized and tested as adsorbents in order to find the most effective derivative for fluoride extraction. The impact of the adsorbent dosage, pH level, contact time, and initial concentration was investigated to assess the feasibility of the chitosan/orange peels/activated carbon@MgO composite. According to the results, the modification of chitosan with AC, OP, and MgO in a unique adsorbent (CS/OP/AC@MgO), especially in acidic conditions (pH 3.0 ± 0.1) by using 1.0 g/L of the adsorbent, demonstrated the highest efficiency in F removal, up to 97%. The pseudo-second (PSO) order model and Langmuir isotherm model fit better to the experimental results, especially for CS/OP/AC@MgO, providing a Qm = 26.92 mg/g. Thermodynamic analysis confirmed the spontaneous nature of the adsorption process. The structure and morphology of the modified OP/CS@AC-Mg were extensively characterized using BET, XRD, FTIR, and SEM techniques.

Visible-light-assisted peroxymonosulfate activation using MIL-88A(Fe)/BiOI heterojunction composite to drive charge transport for eliminating acid red 18

A novel rod-shaped MIL-88A(Fe)/BiOI heterojunction composite is fabricated by an in-suit chemical deposition method for visible-light-assisted peroxymonosulfate activation to eliminate AR18 (acid red 18). A series of x%MIL-88A(Fe)/BiOI are obtained according to the mass ratio of MIL-88A(Fe) to BiOI. Among them, 30 %MIL-88A(Fe)/BiOI could remove 97.79 % AR18 within 40 minutes. The reaction parameters on this process are investigated, such as PMS concentration, catalyst dosage, initial pH and dye concentration. The optimal conditions are determined to be [catalyst]= 1 g·L−1, [PMS]=1 mM, pH=7.02. The scavenging experiments and EPR analysis manifest that 1O2 is the main active species for AR18 degradation. In accordance with the band structure, active species, XPS, PL, EIS and photocurrent response, the Z-scheme electron transfer path of the composite catalyst is proved under 500 W (λ > 420 nm) Xenon lamp irradiation. In the end, the stability and universality of the composite catalyst in practical application are evaluated by three cyclic tests and inorganic anion experiments. This work provides valuable guidance for synthesizing efficient and stable MOF based heterojunction photocatalysts.

Exploring sustainable solutions: Utilizing recycled coffee grounds as a new bio‐adsorbent material for removal of Pb(II) ions from water

AbstractThis study investigates the potential of utilizing spent coffee grounds (SCG) treated with Ca(OH)2 as an adsorbent for the removal of lead (Pb(II)) ions from aqueous solutions. The SCG was subjected to sequential treatments, including washing, drying, sieving, and immersion in Ca(OH)2 solutions of varying concentrations. Adsorption experiments were conducted under different conditions to evaluate the efficiency of the adsorbent, including variations in contact time, solution pH, adsorbent dosage, temperature, and initial Pb(II) ion concentration. Characterization of the SCG before and after treatment was performed using Fourier transform infrared spectroscopy. The results revealed significant changes in the structural properties of the SCG after treatment with Ca(OH)2, leading to enhanced adsorption performance. The adsorption experiments demonstrated that the efficiency of Pb(II) ion removal was influenced by factors such as contact time, solution pH, adsorbent dosage, temperature, and initial Pb(II) ion concentration. Optimal conditions for maximum adsorption efficiency were identified as a contact time of 270 min, pH 6, adsorbent dosage of 1 g, and temperature of 313 K, resulting in a maximum adsorption capacity qmax of 18.69 mg g−1. The highest desorption rate was observed using HNO3, measured at 90.6%. The reusability efficiency of the adsorbent material was 87.98% in the first use, decreased to 75.41% after five reuses, and further reduced to 39.96% after ten reuses, indicating a decline in performance with repeated use. These findings highlight the potential of SCG as an effective and environmentally friendly adsorbent for the removal of potentially toxic elements from aqueous solutions.

Biosorption of methylene blue by bone meal: experimental and modeling with machine learning and full factorial design

Sorption technologies have been proposed for the treatment of water containing methylene blue (MB), a toxic and persistent pollutant. Despite its environmental risks, the role of process variables in MB removal has not been fully explored through experimental design. The objective of this study is to assess the potential of bone meal powder (BMP), an underexplored agricultural byproduct, as an affordable adsorbent for the removal of MB from water. BMP was subjected to a series of analytical characterization techniques, and its adsorption capacity was evaluated through a comprehensive factorial design, which investigated the effects of biosorbent dosage, solution pH, and initial MB concentration. The study revealed that the highest adsorption level was 14.49 mg g−1, attained under the following conditions: 1 g L−1 BMP, pH 11, and 100 mg L−1 MB. The adsorption equilibrium was reached within 60 min, with a measured capacity (qexp) of 18 mg g−1. Theoretical adsorption isotherms indicated a capacity of 63 mg g−1, which aligned well with the Langmuir model. To predict adsorption outcomes, machine learning models were applied, with multiple linear regression performing best. Optimization of decision trees and neural networks improved accuracy but risked overfitting. FT-IR, XRD, and ICP analyses indicated ion exchange as a significant mechanism of adsorption. In desorption studies, H2SO4 was the most effective agent, achieving 68.72% desorption efficiency. BMP exhibited optimal recyclability for up to four cycles before efficiency declined.

Advanced chitosan-based composites for sustainable removal of Congo red from textile wastewater

The non-biodegradable Congo red (CR) dye which is widely used in textile industries has poses carcinogenic risks due to its complex reactions that may generate benzidine. Effective treatment of industrial effluent containing CR dye is imperative. This study assessed chitosan (Cs) and chitosan/fly ash (Cs/Fa) composites for biosorbing CR dye from synthetic textile wastewater. Fly ash varied in the range of (1:0.25–1:1) with chitosan to assess adsorption performance. Characterization techniques included FTIR, SEM, EDX, BET, and zeta potential analyses. Response surface methodology guided the determination of optimal variables. The study examined Cs and Cs/Fa dosage (A), time (B), and initial dye concentration (C) effects on CR removal. Incorporating fly ash substantially cut adsorption costs by 50% while enhancing dye removal up to 85% at pH 6. Improved acidic stability of chitosan (Cs/Fa 1:0.75) was notable. Chitosan (Cs) exhibited a high Congo red removal efficiency of 98% while the chitosan/fly ash (Cs/Fa) composites showed a substantial removal efficiency of 94%. Optimal conditions were 2 g L−1 of adsorbents, initial CR concentration of 40 mg L−1 for 120 min. Freundlich isotherm model best described adsorption behavior. Pseudo-second-order kinetics correlated significantly (R2 = 0.999). This study showed the potential of Cs and Cs/Fa bio-composites for effective textile wastewater treatment.

Optimization of the use of Moringa oleifera in wastewater treatment by rotational central composite design

Textile effluents have a complex waste composition due to the various compounds present and their resistance to degradation. Given the harmful effects of these pollutants on aquatic ecosystems, adequate treatment before disposal is essential, usually involving chemical processes such as coagulation and flocculation. This study optimizes textile wastewater treatment using Moringa oleifera as a natural coagulant through Rotational Central Composite Design (RCCD), a type of Response Surface Methodology (RSM), aiming to improve color removal, a key factor for effluent quality. By exploring Moringa oleifera as a sustainable alternative, the research provides new insights into environmentally friendly coagulant use and treatment optimization. The treatment’s effectiveness depends on the coagulant dosage, the energy applied, and the pollutant concentration. Dye removal was evaluated using spectrophotometry, and the evaluated factors in the optimization process were slow and fast mixing times, coagulant dosage, and pollutant concentration. The study identified pollutant concentration and slow mixing time as the most influential factors in treatment effectiveness. The model achieved a coefficient of determination (R²) of 87.9 %, and maximum dye removal reached 80.2 % under optimal conditions: 30 mL of coagulant, 20 min of slow mixing, 2 min of fast mixing, and a pollutant concentration of 300 mg ∙ L−1. The average removal efficiency was 47.86 %, indicating that natural coagulants offer a viable alternative for textile effluent treatment.

Assessment of photocatalytic activities of layered double hydroxide@petrochemical sludge biochar for sulfamethoxazole degradation

Layered double hydroxides (LDHs) as one of the popular photocatalysts have the drawbacks of compact structural arrangement and pronounced nano-particle clustering, which affect their photocatalytic performance for the degradation of organic pollutants from water or wastewater. Using biochar as a substrate matrix to support LDHs may be a good way to improve the photocatalytic performance of LDHs by avoiding agglomeration effect, promoting the separation of photogenerated electrons from holes for organics degradation. In this study, the composite of CoFe-LDH and petrochemical sludge biochar (CoFe-LDH@PBC) was fabricated and applied for the first time as photocatalyst for catalytic degradation of sulfamethoxazole (SMX). Results showed CoFe-LDH@PBC800/UV system exhibited excellent photocatalytic activity on SMX degradation than single CoFe-LDH/UV, PBC800/UV, or PBC105/UV system under various reaction conditions (photocatalyst dosage, pH, system speed, and SMX concentration). 100 % of SMX degradation efficiency and 88.98 % mineralization efficiency could be achieved in CoFe-LDH@PBC800/UV system within 100 min. The corresponded pseudo-first-order kinetic rate constant (kobs) of SMX degradation in CoFe-LDH@PBC800/UV system was 0.032 min−1, which was 3.20, 8.00, and 2.46 times higher than that of CoFe-LDH/UV, PBC800/UV, and PBC105/UV, respectively. In photocatalytic process, OH, O2−, and h+ participated in SMX degradation, among which h+ or OH played a major role. The good photocatalytic performance of CoFe-LDH@PBC800 composite was related to its excellent physiochemical properties, such as lower band gap (2.39 eV), high graphitization degree, and high conductivity, enabling efficient e−/h+ separation of photocatalyst for SMX degradation. Four distinct pathways of SMX degradation were proposed based on DFT theoretical calculations and byproducts of SMX degradation identified by LC-MS. Additionally, results from recycling tests suggested CoFe-LDH@PBC800 composite possessed a favorable reusability and could be applied for photocatalytic degradation of SMX at least 3 times. Over all, CoFe-LDH@PBC800 composite was proved to be an efficient photocatalyst for antibiotic degradation in water or wastewater and the reuse of petrochemical wastewater sludge was expected to realize the concept of resourceful and high-value utilization of waste biomass.

Innovative metal−phenolic nanocomposite sorbent: A groundbreaking solution for arsenic-free drinking water – Synthesis and characterization approaches

Arsenic (As) stands as one of the most alarming contaminants, presenting a formidable challenge in the realm of drinking water across numerous countries. To deal with this challenge, the sequestration of arsenic by Adsorption has been extensively investigated in the solid media. Here, a sorbent system based on a polyphenolic network with physical cross-linking using tannic acid and ZrIV ions is investigated for high binding, which is in the form of metal sequestration. The derived solvent system of nano adsorbent molecules was characterized using x-ray diffraction analysis (XRD), energy dispersive x-ray spectroscopic (EDS) and Fourier transform infrared (FTIR) spectroscopic techniques. Adsorption of As was studied under varying governing factors such as pH, adsorbent dosage, and metal ion concentration, and the effects of changing these parameters were documented. Maximum adsorption was observed at solution pH-7, 1 gL−1, and 20 mgL−1 metal ion concentration with removal efficiency reaching up to 95 % in 90 min. Adsorption isotherm and kinetics were studied to deduce the mechanism of adsorption as homogeneous monolayer chemisorption and were best fitted by the Langmuir isotherm model and pseudo-second-order kinetics. Considering the extent of As contamination in the groundwater and the associated health risk to the population, our work provides insides into the nanostructure-dependent capability for As adsorption applications.

Nano-eco catalysis: carbendazim degradation by engineered BiVO4 nanoparticles

This study utilized the solvothermal approach for the effective synthesis of BiVO4 nanoparticles. Morphological examination of BiVO4 was conducted via scanning electron microscopy (SEM), while the elemental composition was determined using energy dispersive x-ray spectroscopy (EDX). The crystallinity and functional groups were assessed through x-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR), respectively.The synthesized material’s efficacy in UV-induced breakdown of carbendazim was investigated. The study explored various factors affecting the photodegradation process, including radiation duration, initial concentration of carbendazim, catalyst dosage, and catalyst regeneration. Interesingly, 97% degradation of carbendazim was observed at optimized conditions. These results emphasise the potential of BiVO4 nanoparticles as catalysts for environmental remediation applications, especially in the degradation of harmful contaminants.

Heterogeneous Photo-Fenton Degradation of Azo Dyes over a Magnetite-Based Catalyst: Kinetic and Thermodynamic Studies

Textile wastewater containing dyes poses significant environmental hazards. Advanced oxidative processes, especially the heterogeneous photo-Fenton process, are effective in degrading a wide range of contaminants due to high conversion rates and ease of catalyst recovery. This study evaluates the heterogeneous photodegradation of the azo dyes Acid Red 18 (AR18), Acid Red 66 (AR66), and Orange 2 (OR2) using magnetite as a catalyst. The magnetic catalyst was synthesized via a hydrothermal process at 150 °C. Experiments were conducted at room temperature, investigating the effect of catalyst dosage, pH, and initial concentrations of H2O2 and AR18 dye. Kinetic and thermodynamic studies were performed at 25, 40, and 60 °C for the three azo dyes (AR18, AR66, and OR2) and the effect of the dye structures on the degradation efficiency was investigated. At 25 °C for 0.33 mmolL−1 of dye at pH 3.0, using 1.4 gL−1 of the catalyst and 60 mgL−1 of H2O2 under UV radiation of 16.7 mWcm−2, the catalyst showed 62.3% degradation for AR18, 79.6% for AR66, and 83.8% for OR2 in 180 min of reaction. The oxidation of azo dyes under these conditions is spontaneous and endothermic. The pseudo-first-order kinetic constants indicated a strong temperature dependence with an order of reactivity of the type OR2 > AR66 > AR18, which is associated with the molecular size, steric hindrance, aromatic conjugation, electrostatic repulsion, and nature of the acid–base interactions on the catalytic surface.

Activation of Peroxymonosulfate using a novel heterogeneous catalyst SO-gCN@ZIF-67 for excellent degradation of Brilliant Green dye

This work presents a design of a novel heterogeneous catalyst, SO-gCN@ZIF-67, comprising Co-based MOF, ZIF-67, over a two-dimensional S and O co-doped graphitic carbon nitride nanosheet is reported. This novel heterogeneous SO-gCN@ZIF-67 catalyst is used to degrade organic polluting dyes by activating Peroxymonosulfate (PMS) at room temperature. Various analytical and spectroscopic techniques, such as PXRD, FT-IR, FE-SEM, EDS, HR-TEM, XPS, and UV-DRS, were employed to characterize the as-synthesized nano-catalyst. The as-prepared catalyst can activate PMS effectively to rapidly decolorize the Brilliant Green dye (BG dye) solution at room temperature. The catalyst SO-gCN@ZIF-67 showed high efficiency for PMS activation and decolorization of approximately 96.7 % BG dye with a catalyst concentration of 80.0 mg/L, which was achieved in 15 min. The degradation of the dye obeyed pseudo-first-order kinetics with a reaction rate constant of 0.2262 min−1. Further, the parameters that could influence the activation of PMS, such as the role of different catalysts, catalyst dosage, PMS dosage, and initial dye concentration, were also investigated. Radical trapping experiments revealed that O2− radicals and non-radical singlet oxygen, 1O2, were involved in the degradation of BG dye. A plausible mechanism for the degradation has been proposed using SO-gCN@ZIF-67 and the PMS system.

Fe3+ augmentation enhancing the nitrogen and phosphorus control in denitrification biofilter based on water supply sludge: Performance and microbial characteristics

The intricate mechanisms of iron (Fe) enhancing the simultaneous nitrogen (N) and phosphorus (P) removal in the denitrification biofilter (DNBF) remain enigmatic and warrant further investigation. Fe2+ and Fe3+ were added to compare the enhancing performances and the dosage concentration was optimized in this study, and the effects of Fe3+ on microbial characteristics were elucidated furtherly. Results demonstrated that the N removal performance with Fe3+ enhancing was better than Fe2+, and the optimal FeCl3 concentration was 0.56 mg/L. The effluent concentrations of total phosphorus (TP), total nitrogen (TN), and chemical oxygen demand (COD) lowed to 0.27, 4.2, and 13.4 mg/L, respectively. Fe3+ promoted microbial richness and diversity, with Proteobacteria, Bacteroidetes and Firmicutes emerging as the advantageous phyla for N and P removal in the DNBF. Microorganisms facilitated Fe3+ reduction to enhance denitrification process, and P was predominantly removed through the precipitation formed by the interaction of Fe and P. Furthermore, Fe3+ was noted to promote functional metabolism, thereby aiding in N removal. This study can reveal the effect of Fe3+ on N removal in the DNBF, and provide a theoretical foundation for advanced N and P removal.