Dye Effluent Research Articles

Advanced sulfonated polyester nanofiltration membranes for superior dye separation, desalination, and chlorine resistance

This study introduces an innovative thin-film composite (TFC) nanofiltration membrane made from sulfonated polyvinyl alcohol (SPVA)-based polyester, specifically engineered for effective wastewater treatment. This novel membrane is developed through interfacial polymerization on a polysulfone substrate, demonstrating exceptional water permeability and filtration efficiency. It is particularly effective in separating dyes and salts due to its superior hydrophilicity, optimized surface charge, and precisely tailored morphology. Critical fabrication parameters were finely tuned, utilizing a 2 wt% SPVA solution and a 0.35 wt% trimesoyl chloride (TMC) in the organic phase, with both immersion and polymerization times set at 2 min. The performance metrics are outstanding, featuring a water permeance of 97 L m−2 h−1·bar−1, high dye rejection rates (99.51 % for Congo Red and 99.55 % for Brilliant Blue), and significant salt permeability (30.35 % for Na2SO4 and 29.93 % for MgSO4). The membrane also exhibits excellent antifouling properties, robust chlorine resistance (up to 48,000 ppm h), and sustained operational stability, underscoring its industrial viability for dye and textile effluent treatment. The TFC-SPVA membrane addresses critical environmental challenges in wastewater management, marking a significant advancement in membrane technology.

Selenium-Doped Biochar for Removal of Anionic Acid Red and Cationic Crystal Violet Dye

The environmental impact of untreated dye effluent is a concern due to potential mutagenic and allergic effects. This study aims to develop a cost-effective selenium-doped biochar as an adsorbent material to remove acid red (AR) and crystal violet (CV) dyes from water. Selenium nanoparticles (SeNPs) were produced using chemical and biological synthesis methods. The SEM, EDX, XRD, FTIR, and BET surface analysis methods were used to characterize the biochar and selenium-doped biochar (Se-AC and BSe-AC) samples. Surface modification with SeNPs resulted in an increase in surface area to 14.560[Formula: see text]m2/g for Se-AC and 85.456[Formula: see text]m2/g for BSe-AC. Different adsorption isotherms (Langmuir, Freundlich, and Temkin) and adsorption kinetic models (pseudo-firstorder, pseudo-secondorder, and intra-particle diffusion kinetics) were investigated to understand the adsorption patterns of biochar, Se-AC, and BSe-AC. The maximum adsorption capacities of biochar, Se-AC, and BSe-AC for AR and CV dye were found to be between 0.48[Formula: see text]mg[Formula: see text]g[Formula: see text] and 7.51[Formula: see text]mg[Formula: see text]g[Formula: see text], 2.31[Formula: see text]mg[Formula: see text]g[Formula: see text] and 7.86[Formula: see text]mg[Formula: see text]g[Formula: see text], and 6.88[Formula: see text]mg[Formula: see text]g[Formula: see text] and 9.09[Formula: see text]mg[Formula: see text]g[Formula: see text], respectively, at 313[Formula: see text]K. The obtained negative [Formula: see text] indicates effective adsorption, while a positive [Formula: see text] suggests an endothermic reaction for both dyes. BSe-AC is an eco-friendly alternative to biochar for removing AR and CV.

Effective dye detoxification by Cassia fistula flower extract- powered photocatalytic nanocomposite, SnO2:Mo/rGO and phytotoxicity evaluation of treated water using cowpea seeds

As industrial effluents consisting of toxic organic dye molecules cause severe harms to humans and damages to the environment, the detoxification of industrial waste water becomes one of the priority areas to be considered by countries all over the world. In this context, the present study is focused on the synthesis of an eco-friendly nanocomposite SnO2:Mo/rGO to photo-catalytically detoxify dye effluents. The detoxifying efficiency of this photocatalytic nanocomposite prepared using the flower extract of Cassia fistula was examined by decomposing methylene blue (cationic-MB) and rose bengal (anionic-RB) dyes. The nanocomposite is found to be superior compared to its constituents (SnO2:Mo and rGO) for both MB (99 %) and RB (98 %) dyes. After treatment, the water was examined for its non-toxicity by supplying it for seed germination process using Cowpea seeds (Vigna unguiculata). The seed germination results clearly reveal that near complete detoxification of dye solution is achieved, when SnO2:Mo/rGO nanocomposite is used as photocatalyst. Thus, the SnO2:Mo/rGO nanocomposite synthesized using Cassia fistula flower extract can be considered as a potential photocatalyst for commercial dye detoxification processes.

Isolation and Characterization of Bacterial Consortia for Bioremediation of Textile Dye Effluent

Isolation and Characterization of Bacterial Consortia for Bioremediation of Textile Dye Effluent

Biodegradation of Malachite Green Dye by Novel Isolated Bacillus Species AAV from Garden Soil

Malachite green (MG) dye commonly use in textile and paper printing industry to a great extent. Textile effluent released from industries including dyes must be treated before release into the environment due to its toxic nature. In present study, newly isolated bacterial species was able to decolorize MG dye (100%) in 1 h at shaking condition and 94% at static condition. 16S rRNA analysis revealed an isolate as Bacillus sp. AAV. Lignin peroxidase, laccase and tyrosinase enzymes from Bacillus sp. AAV showed significant increased activity during decolourisation. There was 138, 369 and 164% trek in activity of LiP, laccase and tyrosinase after MG decolourization, respectively. Bacillus sp. AAV could decolourise MG efficiently at alkaline pH (8-10) and at 40°C temperature. Biodegradation was monitored by UV-VIS spectrophotometer. Gas chromatography-Mass spectroscopy data was used to propose the degradation pathway of MG dye. The newly isolated Bacillus sp. AAV was able to decolourise ten various types of dyes and textile dye effluent. Phytotoxicity test by using seeds of wheat and sorghum was also carried out to check toxicity of MG dye metabolites. The study reveals that there was no toxicity with respect to tested seeds. This study suggests that Bacillus sp. AAV could be a useful microorganism or its enzyme system for textile dyes and effluent treatment.

Efficient synthesis of magnetic activated carbon from oak pericarp for enhanced dye adsorption: A one-step approach

This study presents a one-step synthetic method utilizing oak pericarp treated with FeCl3 and ZnCl2 as a precursor for the production of magnetic activated carbon (MAC). Characterization techniques including FTIR, SEM-EDX, TGA, XRD, VSM, BET, and pHpzc confirm the integration of biochar characteristics and magnetic properties of iron oxides in the MAC composite. Batch adsorption tests investigate the adsorption capacity of Rhodamine B (RhB) and Rose Bengal (RB) dyes by MAC under varied conditions, including adsorbent dose, contact time, solution pH, ionic strength, temperature, and initial dye concentration. Optimal adsorption conditions for RhB and RB are identified at pH 2 and 7, with adsorbent doses of 0.75 g/L and 1 g/L, and equilibrium times of 180 min and 120 min, respectively. Adsorption isotherm models (Langmuir, Freundlich, and Temkin) are employed, with the Freundlich model providing the best fit. MAC demonstrates a maximum monolayer adsorption capacity of 198.529 mg.g−1 for RhB and 42.551 mg.g−1 for RB at 20 °C. Kinetic data align with the pseudo-second-order model, and thermodynamic parameters confirm the spontaneous and endothermic nature of the adsorption process. In conclusion, this study successfully synthesizes magnetic biochar with enhanced efficacy in dye adsorption. The one-step method proves efficient for treating industrial dye effluents, as evidenced by batch desorption studies over four cycles, establishing the reusability of the MAC.

Revealing the Enhanced Visible-light-driven Photocatalytic Activity of In2S3/CeO2 Heterojunction: Bandgap Structure Analysis and Active Radicals Determination

Background: The widespread presence of persistent organic pollutants, such as dyes in effluent from printing and textile industries, poses a significant threat to aquatic life and human health. Photocatalytic degradation is widely recognized as a promising technology to address this pollution crisis. The efficiency of photocatalysis is intricately tied to both the active radicals and the band structure of the catalyst. These factors play a crucial role in governing the photodegradation of dye molecules. Methods: In2S3/CeO2 heterojunctions were synthesized using an in-situ precipitation method and subsequently analyzed through SEM, XRD, and XPS techniques. Notably, the bandgap structure of the heterojunctions was examined through UV-Vis DRS. The photocatalytic performance of the synthesized samples was assessed by studying the degradation of methyl orange. To further validate the photocatalytic process, EPR spectroscopy was employed to confirm the presence of radicals generated within the heterojunction. Results: The heterojunction displayed a characteristic type-II structure, enhancing light absorption and facilitating the separation of photoinduced carriers. Among the In2S3/CeO2 composites, the one with a 15 wt% CeO2 content exhibited the highest photocatalytic activity, achieving an 88% degradation of methyl orange after 90 min of exposure to visible light irradiation. Additionally, •O2 − is identified as the primary active species responsible for degradation. Conclusion: UV-Vis DRS illustrated the improved transfer and separation of photogenerated electrons attributed to the optimized band structure of the heterojunction. EPR spectroscopy yielded valuable information on active radicals, thereby proposing the photocatalytic degradation mechanism.

Advancement of sustainable trypan blue degradation through rice husk ash based-heterogenous Fenton catalyst and study with gaussian process regression

Dyes and their derivatives have been found to be harmful to aquatic organisms, and discharging dye effluent without proper treatment into the environment can lead to affect the usability of water for distinct purposes, including drinking water, agriculture, and commercial processes. To overcome this environmental crisis a cost-effective rice husk ash (RHA) derived catalyst was synthesized as Fenton catalyst and a new, environmentally, and friendly treatment was used to treat trypan blue (TB) from synthetic wastewater. SEM, EDX, XRD, and FTIR were used to describe the prepared catalyst's comprehensive characterization. The optimization of degradation was observed with the batch study, while the reaction time was 1 h at 313 K with 180 ppm catalyst and 200 ppm of H2O2 under pH of 3. DNA study of treated and untreated wastewater demonstrated the non-toxic nature of treated trypan blue containing wastewater. For the betterment of water quality monitoring system Gaussian process regression (GPR) model was introduced for dye degradation determination and prediction in aqueous medium. By managing and controlling dye levels, treatment plants can mitigate the negative effects on receiving water bodies and ecosystems. The production cost of catalyst per kg of rice husk ash was estimated to $ 15.4803 which can be reused up to four cycles with minimum efficiency of 87 %. The outcomes unequivocally demonstrated that the suggested approach offered a completely sustainable resolution for reducing various forms of waste.

Comparative adsorption of cationic and anionic dye by using non-activated Black Plum seed biochar for aquatic phase: Isotherm, kinetic and thermodynamic studies

Industrial dye effluents play a major role in water pollution. Textile and leather industries are one of the important sectors that pollute the water by discharging many harmful cationic and anionic dyes during the dyeing process. This study aims to compare the dye removal efficiency of Black Plum seed biochar for the cationic and anionic dyes. The non-activated biochar was prepared through pyrolysis of Black Plum seed powder at 5700 C. The sample's surface chemistry was understood using various characterization techniques like Field Emission Scanning Electron Microscopy (FESEM), Energy-dispersive X-ray spectroscopy (EDS), Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), Raman-Spectroscopy and Zeta-potential. The experiments were successfully performed by conducting a batch adsorption study at different parameters such as pH, concentration, contact time and temperature. The coefficients of different isotherms and kinetics models were evaluated for non-linear study and the thermodynamic model was also applied. The maximum adsorption capacity was obtained as 42.39 mg/g for Crystal Violet (CV) dye and 6.22 mg/g for Eosin Blue (EB) dye by using the Langmuir isotherm model. Hence, the Black Plum seed biochar (BPSB) has superior adsorption capacity for the cationic dye CV ( removal - 98%) as compared to the anionic dye EB ( removal - 65%) at optimum parameters. Therefore, it is concluded that the BPSB is a natural toxin-free biosorbent and it can be used for the remediation of dyes from industrial wastewater.

Application of chemically modified waste tucumã (Astrocaryum aculeatum) seeds in the biosorption of methylene blue: kinetic and thermodynamic parameters.

Dye effluents cause diverse environmental problems. Methylene blue (MB) dye stands out since it is widely used in the textile industry. To reduce the pollution caused by the MB, we developed biosorbents from tucumã seeds, where the in natura seeds were treated with NaOH (BT) and H3PO4 (AT) solutions and characterized by Boehm titration, point of zero charges, FTIR, TGA, BET, and SEM. It was observed that the acid groups predominate on the surface of the three biosorbents. The process was optimized for all biosorbents at pH = 8, 7.5g/L, 240min, C0 = 250mg/L, and 45 ℃. BT was more efficient in removing MB (96.20%; QMax = 35.71mg/g), while IT and AT removed around 60% in similar conditions. The adsorption process best fits Langmuir and Redlich-Peterson isotherms, indicating a hybrid adsorption process (monolayer and multilayer) and pseudo-second-order kinetics. Thermodynamic data confirmed an endothermic and spontaneous adsorption process, mainly for BT. MB was also recovered through a desorption process with ethanol, allowing the BT recycling and reapplication of the dye. Thus, an efficient and sustainable biosorbent was developed, contributing to reducing environmental impacts.

Sustainable Development in Dye Waste Managemen : A Comparative Study on the Effectiveness of Adsorption and γ-Radiolysis

Pyrromethene 567 (PM567), a BODIPY class of dye; is widely used in medicine, chemistry, material science, and high-power dye lasers. During its use, PM567 dye waste is generated in ethanol solvent which needs to be treated before its disposal. In our study, we -radiolysis, an advanced oxidation process (AOP), and adsorption, a simple and easy option. Interestingly, -radiolysis were not efficient for dye effluent treatment in organic solvents. This inefficiency was attributed to competing reactions leading to the scavenging of dye-degrading radicals. -dose rate (3.5 kGy) feasible in the system; 62% is the maximum removal efficiency achieved by this method. For a comparison, we also investigated the adsorption efficiency of PM567 dye from ethanol solvent using commercially available adsorbents. Among these, powdered activated carbon (PAC) demonstrated the highest removal efficiency, reaching 95%, much higher than that of -radiolysis method. In line with the pursuit of sustainable development, we synthesized granular activated carbons (AC1, AC2, AC3) from coconut shells, a lignocellulosic biowaste. The characterization of these carbons revealed that AC3, with a higher iodine value and CCl4 activity, possessed a systematic pore structure (SEM analysis), a larger specific surface area (1708 m2 .g-1), and a higher micro-pore volume (0.61 cc.g-1). AC3 hence, emerged as the most effective adsorbent, achieving 95% efficiency comparable to PAC.

Structure-led manifestation of photocatalytic activity in magnetically recoverable spinel CuFe2O4 nanoparticles and its application in degradation of industrial effluent dyes under solar light

An efficient removal of the photocatalysts used in the decontamination of water is crucial after its application beside its expected visible light sensitive activities. This study presents the synthesis of magnetically separable CuFe2O4 nanoparticles (CFNPs) with enhanced photoactivity under AM 1.5 G sunlight. A simple two-step process involving co-precipitation and hydrothermal treatment is employed, with subsequent annealing at temperatures from 200 °C to 1000 °C to synthesize the CFNPs. The characteristic features of the highest photoactive tetragonal phase of CFNP are confirmed by powder XRD studies with Rietveld refinement. This scheme strategically controls the growth of a highly photoactive tetragonal phase with predominant (224) facets over other less active facets in cubic CuFe2O4. Mott–Schottky analysis confirms the p-type semiconducting nature of CFNPs. A favourable direct optical band gap of 1.73 eV, as well as photoluminescence emission quenching for visible photons, show that the (224) oriented CFNPs are good photocatalysts in the visible spectrum with demonstrated organic dye degradations, including methylene blue and others. A density functional theory-based approach validates that the adsorption of such dye is thermodynamically more favourable on (224) facets of CuFe2O4 to facilitate the redox action by the excitons.

Boosting solar-driven photocatalytic degradation of organic contaminants and bacterial deactivation using marigold- like Cu2O decorated g-C3N4 nanocomposite

Keeping the high efficiency in designing photocatalysts in view, the present work was aimed at the development of a heterojunction photocatalyst with boosted efficiencies, both for degradation of organic contaminants and bacterial deactivation. Heterojunction nanocomposites of g-C3N4 (GCN) and Cu2O (Cu2O /GCN-5 %, Cu2O /GCN-15 %, Cu2O/GCN-25 %, and Cu2O /GCN-50 %) were prepared by hydrothermal method and their photocatalytic performance was evaluated. XPS result confirms the surface chemical composition of nanocomposite and consistent with EDX analysis. The BET studies of Cu2O/GCN −25 % nanocomposite reveals the larger specific surface area (128.10 m2/g), compared to intact Cu2O, which facilitates more active sites on the surface. The optical bandgap energy (2.39 eV-2.58 eV) is tuned towards the visible region by loading g-C3N4 in marigold-like Cu2O. The efficient charge transfer betwixt marigold-like Cu2O and g-C3N4 was demonstrated in PL, CV, and EIS analysis. The Cu2O/GCN-25 % nanocomposite exhibits superior photocatalytic activity towards Aniline blue dye (86.4 %) and β-lactam antibiotic amoxicillin (79 %) under 100 min of sunlight irradiation. HPLC analysis further confirmed the degradation and disintegration of Amoxicillin. The probable photocatalytic mechanism was proposed and tested through a radical scavenger experiment. It was found that ●OH radicals significantly take part in the photodegradation. In addition, the bactericidal activities of Cu2O/GCN-25 % nanocomposite was determined. The highest bactericidal activity was observed for Bacillus subtilis (26 mm). Hence, the marigold-like Cu2O/GCN-25 % nanocomposite is a feasible material for the degradation of dyeing and pharmaceutical industrial effluents as well as bacterial growth inhibition.

Determination of Radium concentration and Radon Exhalation Rates Using CR-39 Detector for Different Geopolymer Cement Samples Containing Industrial Wastes

Natural material like metakaolin, along with industrial wastes such as fly ash (FA), cement kiln dust (CKD), and ground granulated blast furnace slag (GGBFS), are being used to develop new affordable and environmentally friendly construction materials (Geopolymers) that result in reduced carbon dioxide emissions. Geopolymers are gaining attention for their ability to effectively remove organic and inorganic contaminants from wastewater, including dyes and heavy metals. However, the study of the radiation properties of eco-friendly geopolymer cement materials has received little attention. To address this gap, conducted a previous study to examine the radiation properties of different geopolymer cement samples. In this study, the analyzed the radon concentration, radium concentration, and annual effective dose of various pre-treated geopolymer cement samples that contained industrial wastes from dyes and heavy metals. By using the CR-39 detector as a passive technique for this examination. In the pretreated geopolymer cement samples, we used three types of reactive dye effluents - reactive black 5 (BD), reactive red 195 (RD), and reactive yellow 145 (YD) in the presence of heavy metals (Cu2+, Cd2+, and Pb2+). Based on our research, the concentration of radon ranged from 2.69 to 212.42 Bq m-3. The sample with the lowest value of radium concentration was labeled as (10) (GGBFS), while sample (9) (SF10-YD-Cu2+) had the highest value. Found that the annual effective doses were within the range of the world average for indoor and outdoor 1.55and0.58mSvy−1 respectively, except for sample 9 (SF10-YD-Cu2+) which had the highest radium concentration. The pretreated geopolymer cement mixes containing different dye effluents and heavy metals were found to be safe for use in construction areas, except for sample 9 (SF10-YD-Cu2+). Recommend using sample 9 (SF10-YD-Cu2+) only for public highways, bridges, and other well-ventilated buildings.

Assessment of de-toxicity of treated dye solution via seed germination test: Photocatalytic treatment by Morinda citrifolia leaf extract mediated ZnO:Mo/g-C3N4 nanocomposite

Molybdenum doped zinc oxide (ZnO:Mo) nanoparticles and ZnO:Mo/g-C3N4nanocomposites were prepared via green synthesis by using Morinda citrifolia (M. citrifolia) extract as the reducing agent. Another set of ZnO:Mo and ZnO:Mo/g-C3N4 nanomaterials were prepared using NaOH as the reducing agent and their photocatalytic efficiencies against methylene blue (MB) and methyl orange (MO) were evaluated and compared with those of their green synthesized counterparts. The degrading efficiency of green synthesized ZnO:Mo/g-C3N4 was 99 and 96 % against MB and MO of dyes, respectively, whereas the respective values in the case of chemical synthesis are only 95 and 90 %. The mechanism lies behind the photocatalytic activity of the nanocomposite was elaborated. The enhanced charge carrier concentration caused by Mo doping and the synergistic advantages of the composite partners, like band gap reduction and reduced recombination rate are discussed with relevant references. The water samples photocatalytically treated by the nanomaterials were applied to green gram seeds and the growth process is evaluated and compared. The powder XRD, field emission SEM, TEM, FTIR and EDAX results and the related analyses are presented as corroborative evidences for the composite formation and enhanced photocatalytic activity. The prepared green synthesized ZnO:Mo/g-C3N4 nanocomposite will be a promising material for de-toxification of dye effluents to make it conducive for seed germination and plant growth.

Innovative treatment of industrial effluents through combining ferric iron and attapulgite application

The escalation of industrial activities has escalated the production of pharmaceutical and dyeing effluents, raising significant environmental issues. In this investigation, a hybrid approach of Fenton-like reactions and adsorption was used for deep treatment of these effluents, focusing on effects of variables like hydrogen peroxide concentration, catalyst type, pH, reaction duration, temperature, and adsorbent quantity on treatment effectiveness, and the efficacy of acid-modified attapulgite (AMATP) and ferric iron (Fe(III))-loaded AMATP (Fe(III)-AMATP) was examined. Optimal operational conditions were determined, and the possibility of reusing the catalysts was explored. Employing Fe3O4 as a heterogeneous catalyst and AMATP for adsorption, CODCr was reduced by 78.38–79.14%, total nitrogen by 71.53–77.43%, and phosphorus by 97.74–98.10% in pharmaceutical effluents. Similarly, for dyeing effluents, Fe(III)-AMATP achieved 79.87–80.94% CODCr, 68.59–70.93% total nitrogen, and 79.31–83.33% phosphorus reduction. Regeneration experiments revealed that Fe3O4 maintained 59.48% efficiency over three cycles, and Fe(III)-AMATP maintained 62.47% efficiency over four cycles. This work offers an economical, hybrid approach for effective pharmaceutical and dyeing effluent treatment, with broad application potential.

Synergistic photocatalytic degradation of crystal violet dye using novel medical waste-derived carbon/ZnO composite: A study on toxicological assessment

The discharge of crystal violet (CV) dye effluents from textile sectors is a significant concern, as these pollutants not only diminish the aesthetic appeal of water bodies but also impede light penetration, thereby disrupting aquatic ecology. Additionally, the COVID-19 pandemic has led to increased usage of disposable face masks, further contributing to medical waste in the environment. In this state-of-the-art study, the aim was to develop a photocatalyst material using medical-waste-derived carbon (MWC) as a support matrix for zinc oxide (ZnO) nanoparticles, facilitating the photocatalytic degradation of CV dye via persulfate (PS) activation. X-ray diffraction and Raman spectroscopy were used to analyze the crystalline and chemical bonding properties of the synthesized photocatalysts, whilst field-emission scanning electron microscopy and transmission electron microscopy with energy-dispersive X-ray spectroscopy mapping were employed to examine the samples’ surface morphology and composition. The UV–vis spectroscopy and photoluminescence spectroscopy were used to confirm the optical properties of the photocatalysts. The degradation analyses showed that the MWC/ZnO nanocomposite achieved a higher degradation efficiency of 94.4%, with a reusability performance of 91.0% in the fifth cycle. Toxicology assessment was performed using seedling Vigna mungo plants and zebrafish, which revealed significant developmental deformities in the embryos and adults of zebrafish treated with the CV solution, but not when grown with the degraded CV solution or water, supporting the non-toxic nature of the degraded dye water. Therefore, the proposed MWC/ZnO nanocomposite could be suggested as a potential catalyst for CV dye degradation and an ideal solution for both aquatic and medical waste pollutants.

Optimization and modelling of magnesium oxide (MgO) photocatalytic degradation of binary dyes using response surface methodology

Textile industry dye effluent contains a mixture of different kinds of dyes. Many times, photocatalysis is targeted as a solution for the treatment of dye effluent from the textile industry. Many researches have been published related to the photocatalysis of single textile dyes but in the real-world scenario, effluent is a mixture of dyes. Magnesium oxide (MgO) is used as a photocatalyst to treat a mixture (binary solution) of Methylene blue (MB) and Methylene violet (MV) along with individual MB and MV dyes in this article. MgO shows remarkable photocatalytic activity at about 93 and 88% for MB and MV dye in binary solution within 135 min. Furthermore, to study the influence of process parameters, experiments are designed with the help of the central composite design (CCD), and Response surface methodology (RSM) is used to study the interactions between parameters. For this study, five parameters are selected i.e., Photocatalyst dosage, initial concentration of both dyes, time of exposure to the light source, and pH of the binary solution. The photocatalytic process is also optimized and finally optimization of process parameters is validated with an experiment. The result of the validation experiment is very close to the predicted photocatalytic activity.

Comprehensive study of Fenton reaction efficiency on textile wastewater treatment from dye solution to real effluent with emphasis on Fukui function analysis

This study investigated the continuous degradation monitoring of three reactive dyes, reactive yellow 176 (RY), reactive Blue 4 (RB) and reactive red 293 (RR), both in separate solutions and in a mixture, along with their corresponding dye bath and industrial dyeing effluent, using Fenton reaction. A kinetic study was conducted to compare the degradation efficiency of the studied solutions. This work provides important yield of dye degradation, where the results showed that RB, RY, and RR had 96.64 %, 92.47 %, and 73.27 % color removal, respectively, within a two-hour reaction time. The pseudo-second-order model fit well to describe the degradation of RR and RY, while the zero-pseudo-order model provided a better fit for RB. The dye mixture exhibited 57 % color removal, whereas the dyeing bath and real effluent showed 41 % and 36 % removal, respectively, over a two-hour reaction time. Moreover, significant reductions in chemical oxygen demand (COD) and biological oxygen demand over 5 days (BOD5) were observed, with the real effluent demonstrating a 73.91 % COD reduction and an 86.66 % reduction in BOD5. The COD and BOD5 reductions for the dye bath were 67.53 % and 95 %, respectively. Additionally, COD and BOD5 reductions of 72.96 % and 96.66 %, respectively, were observed for the dye bath. DFT calculations were employed to elucidate the regioselectivity of radical oxidation of the three reactive dyes by Fenton's reagent, providing insights into global and local reactivity descriptors. Toxicity studies further underscored the efficacy of the Fenton reaction in wastewater treatment. Additionally, UV–visible spectral analysis before and after 12 h of Fenton reaction revealed total discolouration and a reduction in UV and visible peaks across all reactions, indicating comprehensive dye degradation and reduction.

Preparation of polypyrrole-functionalized recycled cotton fiber as a renewable and eco-friendly cellulose-based adsorbent for water decolorization: Comprehensive batch and fixed-bed column study

Cotton fiber is a low-cost material made from renewable and eco-friendly cellulose and can be used for various applications. However, raw cellulose has a low capacity for capturing pollutants. In this study, recycled cotton fiber was modified with polypyrrole through a chemical oxidative polymerization approach to enhance its implementation and suitability for removing reactive orange 5 (RO5) and reactive yellow 15 (RY15) from aqueous solutions. The cotton/polypyrrole (cotton/ppy) was characterized using SEM, EDS FTIR, and XRD techniques. These analyses indicated that polypyrrole was successfully coated on the cotton fiber. The optimal conditions for maximizing adsorption efficiency, including contact time, concentration of dye, adsorbent dosage, pH levels, and temperature, were determined. RO5 and RY15 eliminations are enhanced in the acidic environment (pH=2, contact time (RO5: 120 min, RY15: 90 min, adsorbent dosage: 200 mg, dye concentration (RO5: 20 mg/L, RY15: 40 mg/L)). The best fit for the adsorption procedure of RO5 and RY15 is the Temkin isotherm model, which indicates a chemisorption process delivers viable mechanism for the adsorption of RO5 (R2 =0.992) and RY15 (R2 = 0.987). Moreover, pseudo-first-order is the leading kinetic model for both RO5 (R2 = 0.999) and RY15 (R2 = 0.995). Furthermore, the study of the fixed-bed column was carried out, showing that the service volume decreased as the flow rate increased. The removal efficiency for RO5 and RY15 exceeded 80% even after using cotton/ppy adsorbent eight times. Therefore, the sustainable polypyrrole-functionalized recycled cotton fiber adsorbent is an excellent choice to eliminate dye effluents.