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The treatment of textile dyeing wastewater represents a remarkable environmental challenge, particularly with the use of natural dyes. Despite their more eco-friendly profile compared to synthetic counterparts, natural dyes contribute to pollution when not fully removed from effluents. Among various remediation techniques, adsorption stands out for its effectiveness, with metal-organic frameworks (MOFs) emerging as promising adsorbents due to their high adsorption capacities and structural stability. This study focuses on the application of a synthesized and characterized MIL-53 (Al) MOF for the adsorption of cochineal extract, a widely used natural red dye in the textile industry, especially handmade carpets. Employing Response Surface Methodology (RSM), we optimized dye removal under varying conditions such as adsorbent amount, temperature, contact time, and pH. Our findings revealed that adsorbent quantity notably influenced the adsorption efficiency, whereas temperature had the least impact, with the highest adsorption capacity observed at 60 °C being 178.57 mg/g. Kinetic analyses indicated that the adsorption process conformed to the pseudo-second-order model, suggesting a physical adsorption mechanism, as further evidenced by an activation energy of 4.914 KJ/mol. Thermodynamic parameters, including changes in enthalpy (ΔH°), entropy (ΔS°), and Gibbs free energy (ΔG°), were determined, revealing an endothermic reaction consistent with physical adsorption. The positive enthalpy change and the spontaneous nature of the process, inferred from a negative Gibbs free energy, underscore the potential of MIL-53 (Al) in efficiently removing cochineal dye from wastewater, contributing to the development of sustainable wastewater treatment strategies in the textile industry. [ABSTRACT FROM AUTHOR]

Due to the severe harmful impacts of industrial dyeing wastewater on ecosystems and human health, proper treatment is crucial. Herein, the use of modified graphite as an adsorbent for dyeing wastewater treatment was investigated in this study. The graphite was oxidized and intercalated using a phosphoric acid–nitric acid–potassium permanganate system and then thermally treated at high temperatures to optimize its structure. By adjusting the thermal treatment temperature, the graphite adsorbent with varying porosity was obtained. The optimized graphite demonstrated significant improvement in adsorption performance for dyes and organic compounds, achieving a removal rate of over 85% for methylene blue (MB) dye. The optimal adsorption performance is achieved with a 1.6 mg modified graphite adsorbent at 60 °C under alkaline conditions for adsorbing 10 ppm MB. Adsorption kinetics and isotherm models were applied to elucidate the adsorption mechanisms. The results fit the Langmuir model, suggesting that monolayer homogeneous adsorption is favorable. Importantly, the results demonstrate that high-temperature treatment can significantly enhance the adsorption properties of coal-based graphite, supporting its application in dyeing wastewater treatment. [ABSTRACT FROM AUTHOR]

This study explores the synthesis and application of Pd-doped CuO-ZnO composites for the simultaneous photodegradation of anionic and neutral dyes. The nanocomposite was synthesized using a hydrothermal technique and characterized using XRD, FTIR, and UV-Vis absorption spectra. Photocatalytic degradation experiments were conducted with varying catalyst loadings, revealing optimal conditions for enhanced degradation performance. The nanocomposite exhibited a synergistic effect on the degradation of the dye mixture, following pseudo-first-order kinetics with significant efficiency under sunlight exposure. Moreover, the study evaluated the influence of pH on the degradation process, showing improved efficiency in neutral and basic conditions. Overall, the findings highlight the efficacy of the Pd-doped CuO-ZnO catalyst in degrading complex dye mixtures, offering potential applications for wastewater treatment in various industrial settings. [ABSTRACT FROM AUTHOR]

This study explores the synthesis and application of Pd-doped CuO-ZnO composites for the simultaneous photodegradation of anionic and neutral dyes. The nanocomposite was synthesized using a hydrothermal technique and characterized using XRD, FTIR, and UV-Vis absorption spectra. Photocatalytic degradation experiments were conducted with varying catalyst loadings, revealing optimal conditions for enhanced degradation performance. The nanocomposite exhibited a synergistic effect on the degradation of the dye mixture, following pseudo-first-order kinetics with significant efficiency under sunlight exposure. Moreover, the study evaluated the influence of pH on the degradation process, showing improved efficiency in neutral and basic conditions. Overall, the findings highlight the efficacy of the Pd-doped CuO-ZnO catalyst in degrading complex dye mixtures, offering potential applications for wastewater treatment in various industrial settings.

In recent years, electrochemical synergistic activation of persulfate (PDS) degradation technology has demonstrated significant potential in wastewater treatment applications. Given the challenges posed by the complex water quality, high COD content, and recalcitrant degradation of dyeing wastewater, this study aimed to evaluate the efficacy of iron/aluminum dual-electrode electrochemical activation of PDS for degrading simulated dyeing wastewater. The results showed that under optimal conditions, utilizing both periodic reversal and direct current electrochemical activation of PDS achieved removal rates of 99.2% and 98.3% for Reactive Black 5 (RB5) and Reactive Red X-3B (RRX-3B), respectively, demonstrating promising removal efficiency. Notably, the removal efficiency of RB5 surpassed that of RRX-3B, suggesting a dependence on initial concentration influencing reaction kinetics. Furthermore, full-spectrum scanning and quenching experiments revealed that RB5 and RRX-3B were primarily degraded through the potent oxidation action of SO4−· and ·OH, with a small number of intermediates present in the solution. Periodic reversal proved effective in mitigating electrode passivation and enhancing electrode longevity. This study provides a highly effective removal method of binary dyes from dyeing wastewater by periodic reversal Fe-Al dual-electrode electrochemical activation of PDS technology, offering valuable insights for sustainable treatment of dyeing wastewater with binary components. [ABSTRACT FROM AUTHOR]

Objectives Since 2016, TOC (Total Organic Carbon) has replaced COD (Chemical Oxygen Demand) as an organic indicator for effluent wastewater quality standards. However, the distribution of organic substances by process in wastewater treatment facilities is not properly identified, making it difficult to secure stable treated wastewater quality. Therefore, in this study, we identified the correlation between TOC and existing organic matter indicators in raw wastewater, primary treated, secondary treated, and effluent wastewater for dyeing wastewater. Methods Samples for each process were collected twice a week, a total of 24 times, from a dyeing wastewater treatment plant located in Y-city, Gyeonggi-do, and organic pollutant indicators (TOC, CODCr, CODMn, BOD5) were analyzed. TOC was analyzed by the NPOC (non-purgeable organic carbon) method using TOC-VCHP (Shimadzu, Japan). Using the analysis results, the characteristics of organic pollutants in dyeing wastewater were analyzed. In addition, multivariate statistical analysis was performed using SPSS to analyze correlations between organic pollutant indicators and principal component analysis. Results and Discussion As a result of multivariate statistical analysis, TOC was inflowed at an average of 574.9 mg/L and treated at 58.2mg/L. In the case of CODCr, CODMn, and BOD5, the inflow was 1,644, 448.9, and 440.7 mg/L and was treated at 98.2, 39.7, and 10.8mg/L. When evaluated based on effluent water quality standards, all of them satisfied the Region III standards, but were discharged at a relatively high level compared to the TOC concentration of sewage treatment plants effluent. As a result of comparing correlations between organic matter indicators through Pearson correlation analysis, the inflow raw water shows a high positive correlation with TOC:TCODCr (r=0.720), TOC:TCODMn (r=0.636), and TOC:TBOD5 (r=0.302) showed low correlation. This is reason to be due to the fact that most organic substances in dyeing wastewater are non-degradable substances and have low biodegradability. As a result of principal component analysis of influent, primary treated, and final treated, three main components each (two for final treated) were extracted, with cumulative contribution rates of 80.1%, 83.2%, and 95.6%. Conclusion Because the properties of wastewater differ greatly depending on the type of leather and chemicals handled at the dyeing factory, the correlation between influent water was low, but the correlation between treated water and treated water was relatively high. The correlation between processes in wastewater treatment facilities also tended to increase toward later processes. It is believed that the above statistical analysis can be used as basic data for effective organic matter management.

This study investigates the influence of photoperiod and wastewater concentration on the growth of microalgae and cyanobacteria for the removal of environmentally significant parameters (COD, BOD, Cr, Fe, color, chlorides, nitrogen compounds, and phosphates) from dyeing wastewater. A two-factor central composite design with surface response was employed, involving two algae species (Chlorella and Scenedesmus sp.) and two cyanobacteria species (Hapalosiphon and Oscillatoria sp.). The findings indicated that extended photoperiods (>13 h) and higher wastewater concentrations (70–80% v/v) enhanced biomass production across all strains. However, Hapalosiphon and Chlorella sp. (1.6 and 0.45 g/L) exhibited better tolerance to the wastewater's high toxicity, resulting in higher biomass concentrations and improved COD and BOD removal by Hapalosiphon sp. (75% and 80%, respectively). Further analysis of the obtained biomass revealed their potential applications. Among the cyanobacteria, Hapalosiphon sp. synthesized the highest concentrations of total proteins and lipids (38% and 28% w/w, respectively), while Oscillatoria sp. displayed a high protein content (42% w/w). In contrast, the algae demonstrated a strong propensity for storing substantial quantities of total carbohydrates (65% and 57% w/w for Scenedesmus and Chlorella sp., respectively). These results signify the feasibility of cultivating photosynthetic microorganisms in industrial dyeing wastewater as a sustainable source of nutrients for targeted metabolite production. [ABSTRACT FROM AUTHOR]

Copyright of Industrial Water Treatment is the property of CNOOC Tianjin Chemical Research & Design Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chemistry & Industry of Forest Products is the property of Chemistry & Industry of Forest Products Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To study the effect of salt on decolorization in reactive dyeing wastewater, a chitosan-gelatin composite copper polymer (CG) was prepared as a catalyst, and its structure was characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Fourier-transform infrared spectroscopy. With the help of CG and H2O2, a heterogeneous Fenton catalytic system was created, and it was then used to decolorize simulated reactive dyeing effluent. The decolorization effect of C.I. Reactive Blue 19 (RB19) in the CG/H2O2 catalytic system was studied with and without NaCl. The effects of the initial pH of the decolorization solution, NaCl, and temperature on the decolorization rate and decolorization kinetic properties of RB19 were investigated. The results show that the catalytic decolorization system containing NaCl has a good decolorization effect in a wide range of neutral and alkaline pH values, and the decolorization rate of the CG/H2O2 catalytic system on the simulated RB19 dyeing wastewater increases with increasing pH value in the pH range of 5~10 and with increasing NaCl concentration. At 50°C for 30 min under neutral and alkaline conditions, the decolorization rate of simulated RB19 dyeing wastewater by CG/H2O2 catalytic system reaches more than 90%. In the CG/H2O2 catalytic system, the kinetic models of the catalytic decolorization system with and without NaCl accord with the pseudo-second-order kinetic model. The decolorization rate constant and the initial decolorization rate with NaCl in the dyeing wastewater are more than 3.9 times higher than those recorded without NaCl. The half decolorization time of dyeing wastewater containing NaCl is at least 74% shorter than that of dyeing wastewater without NaCl at the same decolorization temperature. [ABSTRACT FROM AUTHOR]

Zeolitic imidazolate framework/carbon nanotube (ZIF-67/CNTs) was prepared by precipitation method. ZIF-67/CNTs maintained the characteristics of large specific surface area and high porosity of ZIFs, showing stable cubic structure. The adsorption capacities of ZIF-67/CNTs for Cong red (CR), Rhodamine B (RhB) and Cr(VI) were 36.82 mg/g, 1421.29 mg/g and 716.67 mg/g under the conditions of 2:1, 3:1 and 1:3 masses of ZIF-67 and CNTs, respectively. The optimum adsorption temperature of CR, RhB and Cr(VI) were 30 °C, and the removal rates at the adsorption equilibrium were 81.22%, 72.87% and 48.35%. The adsorption kinetic model of the three adsorbents on ZIF-67/CNTs was consistent with the quasi-second order reaction model, and the adsorption isotherms were more consistent with adsorption law of Langmuir. The adsorption mechanism for Cr(VI) was mainly electrostatic interaction, and the adsorption mechanism for azo dyes was the combination of physical and chemical adsorption. This study would provide theoretical basis for further developing metal organic framework (MOF) materials for environmental applications. [ABSTRACT FROM AUTHOR]

The treatment of dyeing and printing wastewater is a formidable challenge due to its high chemical oxygen demand (COD) and chromaticity, which pose severe threats to both the environment and human health. In this study, a composite modified adsorption material was prepared based on the applicability and feasibility in practical engineering applications. A novel mixed modified adsorbent was developed by incorporating activated carbon and activated clay as the foundation materials, followed by the addition of cetyltrimethylammonium bromide (CTAB) for modification. The performance of the composite adsorbent was evaluated via adsorption experiments of bromophenol blue (BPB) solution and dyeing and printing wastewater. The results demonstrated that the mixed modified adsorbent achieved a remarkable removal rate of 99% for BPB and 99.3% for chromaticity, under the optimal adsorption conditions. Furthermore, the regeneration performance of the mixed modified adsorbent was found to be exceptional. The adsorption process of BPB by the composite adsorbent was governed by the quasi-second-order kinetic model and Freundlich isotherm model, as evidenced by adsorption kinetics and isotherm analyses. The straightforward preparation method, coupled with the superior adsorption performance, underlines the promising potential of the proposed composite adsorbent for practical applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Copyright of Inorganic Chemicals Industry is the property of Editorial Office of Inorganic Chemicals Industry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Advanced Textile Technology is the property of Zhejiang Sci-Tech University Magazines and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Mentha crispa L. is one of Vietnam’s most precious folk medicines and is also a spice used in many delicious dishes in Vietnam and around the world. The use of Mentha crispa L. leaf extract as a reducing agent for Ag+ ions to synthesize silver nanoparticles is discussed in this paper. Single silver nanospheres were dispersed in biological media and their sizes were controlled in the range of 20-80 nm. Factors affecting particle size and shape such as extract concentration, AgNO3 concentration, reaction time, and temperature were investigated to determine the optimal parameters for particle synthesis. The optical properties, dispersion, crystal structure, morphology, and sizes of silver nanoparticles were investigated through UV-Vis absorption spectroscopy, dynamic light scattering (DLS) measurements, X-ray diffraction, and transmission electron microscopy (TEM). The functional groups on the L.AgNPs were determined by Fourier-transform infrared (FTIR) transmittance spectra. The synthesised silver nanoparticles were used to treat methylene blue (MB) dye, the main component of dye wastewater, based on their photocatalytic properties. The results show that in the presence of L.AgNPs, the photodegradation efficiency of NaBH4 or H2O2 reducing agents is much higher, up to 95% of illumination.

The frequent use of an industrial dye such as malachite green (MG) has caused major water body deterioration and is one of the most pressing global challenges, demanding effective treatment techniques. To solve these issues, a simplistic method was developed to synthesize zinc-tungstate (ZnWO4) nanoparticles and also dope the surface matrix of the ZnWO4 nanoparticles using nonmetals of boron (B), carbon (C), and nitrogen (N) at different ratios for enhanced MG removal from wastewater. The prepared nanomaterials were characterized by different methods for crystal structure composition, surface properties, surface morphology, microstructures, functional groups, and elemental oxidation states. The BET analysis revealed a mesoporous structure with surface areas of 30.740 m2/g for ZnWO4, 38.513 m2/g for ZnWO4@BCN, 37.368 m2/g for ZnWO4@BCN/B, 39.325 m2/g for ZnWO4@BCN/C, and 45.436 m2/g for ZnWO4@BCN/N nanocomposites. The best removal of MG was accomplished at pH (8), contact period (50 min), nanoadsorbent dose (0.8 g/L), initial MG concentration (20 mg/L), and temperature (303 K). The maximum adsorption capacities of ZnWO4 and ZnWO4@BCN/N towards MG were 218.645 and 251.758 mg/g, respectively. At equilibrium, the Freundlich isotherm and pseudo-second-order kinetic models were the best fits for the experimental data of MG adsorption on both nanoadsorbents. After eight cycles of adsorption and desorption, both ZnWO4 and ZnWO4@BCN/N were found to be good at removing MG, with efficiencies of 71.00 and 74.20%, respectively. Thermodynamic investigations further validated the spontaneity and endothermic nature of the adsorption process. All study findings confirm the nanoadsorbents exceptional capability and economic feasibility for removing MG dye.

Strict standards have been put forward for the treatment and discharge of dyeing wastewater worldwide. However, there are still traces amount of pollutants, especially emerging pollutants in dyeing wastewater treatment plant (DWTP) effluent. Few studies have focused on the chronic biological toxicity effect and mechanism of DWTP effluent. In this study, 3-month chronic compound toxic effects were investigated by the exposure of DWTP effluent using adult zebrafish. Significantly higher mortality and fatness and significantly lower body weight and body length were found in the treatment group. In addition, long-term exposure to DWTP effluent also obviously reduced liver-body weight ratio of zebrafish, causing abnormal liver development of zebrafish. Moreover, DWTP effluent led to obvious changes in the gut microbiota and microbial diversity of zebrafish. At phylum level, significantly higher of Verrucomicrobia but lower Tenericutes, Actinobacteria, and Chloroflexi were found in the control group. At genus level, the treatment group had significantly higher abundance of Lactobacillus, but significantly lower abundance of Akkermansia, Prevotella, Bacteroides, and Sutterella. These results suggested that long-term exposure to DWTP effluent led to imbalance of gut microbiota in zebrafish. In general, this research indicated that DWTP effluent pollutants could result in negative health outcomes to aquatic organisms. [ABSTRACT FROM AUTHOR]

[Display omitted] In this study, zeolitic imidazolate framework (ZIF-8)/polyvinylidene fluoride (PVDF) loose nanofiltration (NF) hollow fiber membranes were fabricated by constructing ZIF-8 functional layer on the PVDF supporting membranes based on the vacuum-assisted assembly process. The ZIF-8 synthesis was completed in a water system, and the synthesized ZIF-8 suspension was directly added to polyvinyl alcohol (PVA) and halloysite nanotubes (HNTs) aqueous solution system without drying to prepare the casting solution, which could solve the agglomeration and poor dispersion problem of ZIF-8 particles. In addition, the embedded HNTs and the loaded PVA among the ZIF-8 layer could improve the bonding strength between the ZIF-8 layer and the supporting membranes. After constructing ZIF-8 functional layer, the pore size of supporting membranes decreased from more than 300 nm to several nanometers. Furthermore, the water contact angle reduced from 91.1° to 54.2°. Applied to treat dye wastewater, the prepared ZIF-8/PVDF membranes maintained high dye rejection (˃99.0 %) for Congo red (CR), but low salt rejection for NaCl (about 2 %). In addition, the flux could reach 21.6 L m-2h−1 after continuous filtration 360 min, exhibiting a potential for treating the dye/salt wastewater. In particular, there were no organic solvents used in the work, which provided a promising idea for solvent-free fabrication of loose NF membranes. [ABSTRACT FROM AUTHOR]

The fractionation of dye and salt effectively is crucial in the nanofiltration of dyeing wastewater. However, the present commercial nanofiltration membrane often rejected dye and salt simultaneously due to the dense selective layer of the membrane. To obtain nanofiltration membranes with a loose selective layer, β-cyclodextrin (β-CD) was added to the co-deposition of dopamine/polyethyleneimine in the PA/PDA-β-CD/PVDF composite loose nanofiltration membrane by the method of combination of co-deposition and interfacial polymerization. The effect of β-CD content on the structure and morphologies of PA/PDA-β-CD/PVDF composite loose nanofiltration membrane was investigated. The chemical structure, microstructure, surface roughness, and hydrophilicity of the membrane surface were characterized by an infrared spectrometer (attenuated total reflection-Fourier- transform infrared spectroscopy), scanning electron microscope, atomic force microscope, and dynamic water contact angle meter. The filtration performance of the PA/PDA-β-CD/PVDF composite loose nanofiltration membrane was tested by filtration experiments. The results showed that with the increase of β-CD concentration, the hydrophilicity, water flux, and salt permeability of the selective layer were significantly increased, indicating that β-CD had improved the porosity and hydrophilicity of the selective layer. When the β-CD concentration was 2 g/L, the flux of water and dyeing wastewater was the maximum, but the dye rejection was lower than 90%. The performance of the composite nanofiltration membrane with the β-CD concentration of 1 g/L was the best. [ABSTRACT FROM AUTHOR]

The in situ electrochemical oxidation process has received considerable attention for the removal of dye molecules and ammonium from textile dyeing and finishing wastewater. Nevertheless, the cost and durability of the catalytic anode have seriously limited industrial applications of this technique. In this work, the lab-based waste polyvinylidene fluoride membrane was employed to fabricate a novel lead dioxide/polyvinylidene fluoride/carbon cloth composite (PbO2/PVDF/CC) via integrated surface coating and electrodeposition processes. The influences of operating parameters (pH, Cl− concentration, current density, and initial concentration of pollutant) on the oxidation efficiency of PbO2/PVDF/CC were evaluated. Under optimal conditions, this composite achieves a 100% decolorization of methyl orange (MO), 99.48% removal of ammonium, and 94.46% conversion for ammonium-based nitrogen to N2, as well as an 82.55% removal of chemical oxygen demand (COD). At the coexistent condition of ammonium and MO, MO decolorization, ammonium, and COD removals still remain around 100%, 99.43%, and 77.33%, respectively. It can be assigned to the synergistic oxidation effect of hydroxyl radical and chloride species for MO and the chlorine oxidation action for ammonium. Based on the determination of various intermediates, MO is finally mineralized to CO2 and H2O, and ammonium is mainly converted to N2. The PbO2/PVDF/CC composite exhibits excellent stability and safety. [ABSTRACT FROM AUTHOR]

Rapid activation degradation of C.I. Reactive Black 5 (RB5) wastewater with sodium persulfate (SPS) was accomplished using iron-doped MXene (Fe@MXene). The study systematically explored the influence of SPS concentration, Fe@MXene concentration, Fe-to-MXene molar ratio, initial pH, and ion species on the RB5 degradation percentage. The RB5 simulated dye solution, using 3 g/L SPS and 200 mg/L Fe@MXene mixture at 25 °C, stirred for 30 min, resulting in a degradation percentage of up to 99.6 %. Fe@MXene synthesis led to Ti-O bond formation and a 19.04 % reduction in crystallinity due to titanium reduction and iron incorporation. The Fe@MXene catalyst significantly accelerated SPS activation through enhanced electron transfer processes, facilitated by the distinctive structural and functional attributes of MXene, which enable the continuous reduction of Fe3+ to Fe2+. This process promotes the generation of sulfate radicals (SO 4 •–), hydroxyl radicals (‧OH), and singlet oxygen (1O 2), which were identified as the key reactive species driving dye degradation. When using this system to degrade dyeing wastewater, the types of dyes and inorganic salts only affect the degradation rate, not the final degradation percentage. During the five cycles, Fe leaching consistently reached 2.27 mg/L, leading to a 6.75 % decrease in degradation percentage by the fifth cycle compared to the first. The treated dyeing bath was reused in a new dyeing, and excellent coloration property was observed. This study not only enhances the understanding of the catalytic reaction of Fe@Mxene but also provides a highly efficient process for dyeing wastewater treatment, showing promising application prospects. [Display omitted] • Fe@MXene activated sodium persulfate can treat dyeing wastewater effectively. • MXene accelerates the Fe2+/Fe3+ cycle in the sodium persulfate activation reaction. • OH and 1O 2 is the main component that destroy dye. [ABSTRACT FROM AUTHOR]

Keratin-based goat hair could be used bioadsorbent due to its large availability, biodegradability and low cost. Unfortunately, most available keratin adsorbents are either low in adsorption capacity or high in preparation cost. In this study, goat hair was steam exploded, frozen and disintegrated to prepare the exploded goat hair powder (EGHP), and was further used for the adsorption of reactive blue 19 (RB 19) in dyeing wastewater. Steam explosion significantly increased the adsorption capacity of keratin-based goat hair toward RB 19. Adsorption capacity of RB 19 in EGHP increased from 55 to 427 mg/g after a steam explosion under 1.8 MPa for 150 s. The increased adsorption capacity was mainly due to decreased crystallinity, increased specific surface area from 0.678 to 8.583 m2/g and the increased free NH2 groups for EGHP. These structure changes resulted in that more dye molecules could easily and fast entered into the amorphous region of EGHP, thereby improving the adsorption rate and amount of RB 19 dyes. Desorption and regeneration study indicated that the adsorption capacity still maintained 79% after 6 cycles. These results demonstrated that EGHP could be considered as promising bioadsorbent to treat the dyeing wastewater.

In this study, novel chitosan/silica composites with different mass ratios were prepared by in-situ hydrolysis using chitosan (from shrimp shell) as a carrier, triblock copolymer (P123) as the structure-directing agent, and ethyl orthosilicate as a silicon source. These nanocomposites were characterized by different techniques, including the FT-IR, XRD, TGA, SEM, TEM and N2 adsorption–desorption. The results indicated that the morphology and properties of composites changed with the introduction of silica. When the CS/TEOS mass ratio was 0.0775, the CS−2/SiO2 composite displayed a coral-like three-dimensional porous structure with specific surface area of 640.37 m2/g and average pore size of 1.869 nm. The adsorption properties for methylene blue (MB) were investigated as well and the CS−2/SiO2 showed better adsorption performance. The removal rate for MB reached 94.01% with absorbents dosage of 6 g/L, initial concentration of 40 mg/L, initial pH value of 7, temperature of 35 °C, and adsorption time of 40 min. The adsorption process well fitted the Langmuir isothermal model and quasi-second-order adsorption kinetics model. The maximum adsorption capacity for MB was 13.966 mg/g based on Langmuir fitting. The surface functional groups of the composites can play an important role in the adsorption. The adsorption mechanism of CS−2/SiO2 on MB involved electrostatic interaction, hydrogen bonding and functional group complexation. In addition, the prepared chitosan/silica composites showed good reusability at six cycles, making them a promising material in the application of removing dyeing wastewater. [ABSTRACT FROM AUTHOR]

This study investigates the influence of photoperiod and wastewater concentration on the growth of microalgae and cyanobacteria for the removal of environmentally significant parameters (COD, BOD, Cr, Fe, color, chlorides, nitrogen compounds, and phosphates) from dyeing wastewater. A two-factor central composite design with surface response was employed, involving two algae species (Chlorella and Scenedesmus sp.) and two cyanobacteria species (Hapalosiphon and Oscillatoria sp.). The findings indicated that extended photoperiods (>13 h) and higher wastewater concentrations (70–80% v/v) enhanced biomass production across all strains. However, Hapalosiphon and Chlorella sp. (1.6 and 0.45 g/L) exhibited better tolerance to the wastewater’s high toxicity, resulting in higher biomass concentrations and improved COD and BOD removal by Hapalosiphon sp. (75% and 80%, respectively). Further analysis of the obtained biomass revealed their potential applications. Among the cyanobacteria, Hapalosiphon sp. synthesized the highest concentrations of total proteins and lipids (38% and 28% w/w, respectively), while Oscillatoria sp. displayed a high protein content (42% w/w). In contrast, the algae demonstrated a strong propensity for storing substantial quantities of total carbohydrates (65% and 57% w/w for Scenedesmus and Chlorella sp., respectively). These results signify the feasibility of cultivating photosynthetic microorganisms in industrial dyeing wastewater as a sustainable source of nutrients for targeted metabolite production.

The dilemma of diminishing freshwater resources caused by water pollution has always impacted human life. Solar-driven interfacial evaporation technology has the potential for freshwater production via solar-driven distillation. However, in solar-driven interfacial evaporation technology, it is difficult to overcome the problem of wastewater containing various contaminants. In this work, we propose a bifunctional fabric created by depositing titanium dioxide@carbon black nanoparticles onto cotton fabric (TiO2@CB/CF). The TiO2@CB/CF has a coupling effect that includes the photothermal effect of CB and photocatalysis of TiO2, and it can not only generate clean water but can also purify contaminated water. The resulting bifunctional fabric can achieve an outstanding water evaporation rate of 1.42 kg m−2 h−1 and a conversion efficiency of 90.4% in methylene blue (MB) solution under one-sun irradiation. Simultaneously, the TiO2@CB/CF demonstrates a high photocatalytic degradation of 57% for MB solution after 2 h with light irradiation. It still shows a good photocatalysis effect, even when reused in an MB solution for eight cycles. Furthermore, the TiO2@CB/CF delivers excellent performance for actual industrial textile dyeing wastewater. This bifunctional fabric has a good application prospect and will provide a novel way to resolve the issue of freshwater scarcity. [ABSTRACT FROM AUTHOR]

In this paper, the inorganic–organic composite flocculant (PAC/PMAPTAC) was prepared with polyaluminum chloride (PAC) and the self-made PMAPTAC. Then, the flocculation sedimentation experiment was used to evaluate the flocculation performance of single flocculant PAC, PMAPTAC and the composite flocculant PAC/PMAPTAC in dyeing wastewater. At the same time, the flocculation effect of PAC/PDMDAAC was compared with that of PAC/PMAPTAC under the same condition. Finally, the flocculation mechanism was analyzed by zeta potential and floc morphology. The results showed that compared with PAC, the flocculation performance of composite flocculant PAC/PMAPTAC could be markedly improved, resulting in the higher decolorization rate and CODMn removal rate. Besides, the increase of (η) or content of PMAPTAC in PAC/PMAPTAC could enhance the decolorization rate and CODMn removal rate simultaneously. Furthermore, the lower dosage was required to achieve the best removal effect, which meant that the cost of the flocculant was reduced. Moreover, the comparison of flocculation performance turned out that the decolorization rate and CODMn removal rate of PAC/PMAPTAC were higher than those of PAC/PDMDAAC under the same condition. Finally, the zeta potential and floc morphology analysis showed that the flocculation mechanism of the reactive dye simulated wastewater was mainly charge neutralization and adsorption bridging. The above results not only fill the gaps in the research of PAC/PMAPTAC during the treatment of dyeing wastewater, but also provide an experimental basis for its application in dyeing wastewater and expand the application fields of PMAPT AC. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel dual-layer membrane combining a PSF bottom layer and a PH surface layer incorporated with ZIF-71 nanoparticles was developed. • The dual-layer ZIF-71/PH-PSF membrane possessed high permeate flux. • The dual-layer ZIF-71/PH-PSF membrane exhibited high efficiency for dyeingwastewater treatment. • The mechanism underlying the enhanced MD performance of the ZIF-71/PH-PSF membrane was elucidated. Membrane distillation (MD) is a promising technology for the treatment of hypersaline dyeing wastewater. However, commercial membranes still have limitations such as low permeate flux, membrane fouling, and membrane wetting issue in MD process. Herein, a dual-layer MD membrane was fabricated with a polysulfone (PSF) bottom layer and a poly(vinylidene fluoride-co-hexafluoropropylene) (PH) hydrophobic surface layer incorporated with ZIF-71 nanoparticles. The addition of ZIF-71 was optimized based on the results of surface morphology, contact angle, and MD performance. The incorporation of ZIF-71 nanoparticles into PH nanofiber membranes, along with their dual-layer structure, has led to notable improvements in both permeate flux and rejection performance. The fouling resistance of membrane was further evaluated with model dyeing wastewater as feed solution, which contained four types of dyes and heavy metal antimony. The MD performance of the optimized membranes was also measured with real dyeing wastewater as feed solution. The dual-layer membrane decorated with ZIF-71 nanoparticles significantly outperformed the pristine membrane in treating real dyeing wastewater, exhibiting potential for practical applications. Finally, the underlying mechanism on the improved permeate flux and rejection was elucidated systematically. [ABSTRACT FROM AUTHOR]

[Display omitted] • The amphoteric C/A composite sponges were prepared and characterized. • C/A composite sponges possess self-cleaning and multi-active sites. • Sponges' adsorption capacity for MB and AB dyes is 656.33 mg/g and 502.49 mg/g. • The selective adsorption ability of sponges could be modulated by various pH. • C/A composite sponges can be loaded with photocatalysts for dye degradation. To address the complex dyeing wastewater containing oil pollution and bacterial microorganisms in practical environments, in this work, amphoteric (CHI/ALG) C/A composite sponges with self-cleaning and multi-active sites were prepared by composite chitosan (CHI) and alginate (ALG) using urea/alkali composite solutions. The C/A composite sponges have good water wettability and demonstrated underwater anti-oil and anti-bacterial microbial adhesion. The adsorption process was spontaneous entropy-increasing and could be accurately described using the Pseudo-First-Order and Langmuir models. Notably, the adsorption capacity of C/A composite sponges for methylene blue and acid blue dye reached 656.33 mg/g and 502.49 mg/g, respectively. The amphoteric C/A composite sponges can selectively adsorb both anionic and cationic dyes. Additionally, epichlorohydrin (ECH) cross-linking and intermolecular self-assembly molding enabled the C/A composite sponges to form a three-dimensional network structure with nanofiber weaving and a specific surface area of 67.63 m2/g. Interestingly, this endowed the C/A composite sponges with the potential to serve as dyes photocatalyst substrates, and the photocatalytic degradation of dyes was successfully achieved by loading TiO 2 on the C/A composite sponges. More importantly, the C/A composite sponge remained self-cleaning after loading TiO 2. The amphoteric C/A composite sponges have great potential in complex dyeing wastewater treatment containing oil and bacterial microbes. [ABSTRACT FROM AUTHOR]

A new type of polyvinylidene fluoride (PVDF)/polymethyl methacrylate (PMMA) hollow fiber membrane (HFM) with five bores was prepared. The effects of polyvinylpyrrolidone (PVP), β-cyclodextrine (β-CD), polyethylene glycol (PEG) and polysorbate 80 (Tween 80) and their combinations on the PVDF/PMMA five-bore HFMs were investigated. The performance and fouling characteristics of five-bore HFMs for dyeing wastewater treatment were evaluated. Results indicated that adding 5 wt.% PVP increased the porosity and water flux of the membrane but decreased the bovine serum albumin (BSA) rejection rate. Adding 5 wt.% β-CD significantly improved the tensile strength and rejection of the HFMs with no effect on the increase of water flux. The characteristic of the HFMs with different additive combinations proved that the mixture of 5 wt.% PVP and 1 wt.% β-CD gave the best membrane performance, with a pure water flux of 427.9 L/ m2·h, a contact angle of 25°, and a rejection of BSA of 89.7%. The CODcr and UV254 removal rates of dyeing wastewater treatment were 61.10% and 50.41%, respectively. No breakage or leakage points were found after 120 days of operation, showing their reliable mechanical properties. We set the operating flux to 55 L/m2·h and cross-flow rate to 10%, which can effectively control membrane fouling. HIGHLIGHTS PVDF/PMMA five-bore HFMs were prepared by dry-wet spinning.; The addition of PVP and β-CD had significant effects on HFM hydrophilicity and rejection respectively.; The best film properties were obtained by mixing 5 wt% PVP and 1 wt% β-CD.; The laboratory-made membrane module could effectively remove chemical oxygen demand and the turbidity of the dyeing wastewater.; No breakage or leakage points were found after 120 days of operation, showing their reliable mechanical properties.;

A highly-efficient graphitic carbon nitride (g-C3N4) photocatalyst for visible light photodegradation of rhodamine B (RhB) and methyl orange (MO) simulating dyeing wastewater was synthesized by the thermal polycondensation of melamine. The photocatalysts were characterized by TG-DTG-DSC, XRD, EA, XPS, FT-IR, SEM, TEM, BET, PL and UV-vis DRS. The results showed that the photocatalytic performance of g-C3N4 at a higher calcination temperature was significantly enhanced, and its photocatalytic activities for the photodegradation of RhB and MO were remarkably improved by 64.91% and 41.83%, respectively, which was mainly attributed to the satisfactory crystallinity, stable graphene-like structure, large surface area, and excellent optical properties. It was found that •O2− radicals and •OH radicals were the main active species for the photodegradation process by the free radicals trapping experiments and ESR analysis. The photodegradation mechanism of g-C3N4 was proposed predicated using the characterization results. [ABSTRACT FROM AUTHOR]

Electrochemical oxidation is a promising alternative for the degradation of reactive dyestuffs in residual dyeing liquid, which contains organic dyes, as well as salts such as sodium chloride and sodium sulfate. In this work, three kinds of salts, Na2SO4, NaCl and FeSO4, were selected to study the influence of electrolytes on the electrochemical oxidation of recalcitrant reactive red X-3B, using graphite cathode and dimensionally stable anode or graphite anode. The removals of color and chemical oxygen demand have been evaluated. Color removals were 99.97% and 99.84% with graphite anode and dimensionally stable anode in Na2SO4 and NaCl electrolyte. The corresponding chemical oxygen demand removals were 93.60% and 100%. In contrast, the maximum color and chemical oxygen demand removals were 97.32% and 68.76% in FeSO4 electrolyte. It was found that a combination of NaCl and FeSO4 achieved complete oxygen demand removal for both graphite anode and dimensionally stable anode. During the electrochemical oxidation process, anode and electrolyte exhibited a great effect on pH variations. Based on the cyclic voltammetry and active oxidative species investigations, the oxidation of reactive red X-3B was attributed to indirect oxidation of active chlorine and reactive oxygen species. [ABSTRACT FROM AUTHOR]

While printing and dyeing bring us huge economic benefits, it also brings us huge challenges. Printing and dyeing will produce a large amount of wastewater, and the treatment of printing and dyeing wastewater has always been a concern. This work uses 2-methacryloxyethyl dimethyl-3-sulfonic acid propyl ammonium hydroxide, 3-(methacryloxy) propyl trimethoxysilane, and N, N'-methylene bispropylene as raw materials, and a photoinitiator is used to initiate polymerization under an ultraviolet lamp to prepare a copolymer gel. Taking the aqueous solution containing soap yellow as simulated dye wastewater, the adsorption performance of the prepared polymer for dyes was investigated. An ultraviolet spectrophotometer was used to investigate the effects of adsorption time, initial dye concentration, and polymer dosage on the adsorption performance. The performance test results show that the prepared polymer has high adsorption and removal efficiency for dyes containing soap yellow simulation, and has a potential application value. [ABSTRACT FROM AUTHOR]

The anode active material graphite in the waste lithium-ion battery was prepared into graphene oxide, which was used for preparation of graphene aerogel through hydrothermal reduction. Taking Congo red as the model dye contaminant, the effects of graphene aerogel input, initial concentration of pollutants, initial pH, temperature and adsorption time on the adsorption of Congo red were studied. The kinetics thermodynamics of adsorption process was analyzed. The experimental results showed that the adsorption rate was up to 99% under optimal condition. The adsorption process of Congo red by graphene aerogel was in accordance with the Freundlich isotherm adsorption model. The adsorption process was multi-molecular layer adsorption, and the quasi-second-order kinetic equation indicated that the adsorption could be chemical adsorption. The maximum adsorption capacity was 53.91 mg g−1, and the adsorption activation energy was 72.49 kJ mol−1. Our results show that the strategy of using the recycled anode material for dye removal may have high environmental and economic benefits. [ABSTRACT FROM AUTHOR]

Industrial dyeing produces highly polluting wastewater and threatens the environment. Effective treatment of dyeing wastewater is a crucial step to prevent toxic chemicals from entering receiving waters. This study aimed to assess a modified attapulgite (ATP)-based adsorbent for dyeing wastewater purification by introducing chitosan (CTS) and titanium dioxide (TiO2) into the adsorbent material named TiO2/CTS/ATP. It was found that after modification, the adsorbent showed a lower hydrophilicity, as demonstrated by an increase in the water contact angle from 9.1° to 42°, which could reduce the water adsorption tendency and potentially facilitate contaminants adherence. The modification also led to a significantly increased specific surface area of 79.111 m2/g from 3.791 m2/g and exhibited more uniform and smaller particle size (reduced from 3.99 to 2.52 μm). When the TiO2/CTS/ATP adsorbent was applied to the adsorption of Congo red solution, the adsorption efficiency was observed to reach to 97.6% at the dosage of 0.5 g/L. Furthermore, the combination of adsorption and ultrafiltration was able to achieve 99% Congo red removal. Adsorption pretreatment prior to the ultrafiltration also enabled to reduce membrane fouling, increased the reversible membrane fouling, and resulted in a considerably lower transmembrane pressure as compared with the direct ultrafiltration filtration system. [ABSTRACT FROM AUTHOR]

Limited by the service life, a large amount of spent lithium-ion batteries (LIBs) have been produced in recent years. Without proper disposal, spent LIBs can cause environmental pollution and waste of resources. In this paper, we focus on the recycling of the graphite anode (GA) in spent LIBs. GAs from spent LIBs were converted to graphene oxide (GO) through a modified Hummers method. Then the prepared GO was applied to absorb methylene blue in dyeing wastewater under different reaction conditions. The experimental results indicate that GO can quickly and effectively adsorb methylene blue, which also exhibits thermal stability. The maximum adsorption capacity and removal rate are about 833.11 mg/g and 99.95%, respectively. The adsorption kinetics and isotherms were investigated; the adsorption process of GO is more consistent with the pseudo-second-order adsorption kinetic model while the isotherm is close to the Langmuir isotherm. This study is of great significance for the economy and environment. The reaction can turn waste into wealth and is a win-win approach for both spent LIBs recycling and dyeing wastewater cleaning.

With the development of resource recycling awareness, the number of research on the synthesis and utilization of carbon dots (CDs) from natural wastes continues to grow. Meanwhile, the little-studied synthesis of CDs originating from industrial waste has also become more relevant. In this work, reactive yellow 95 (Y95) molecules in exhausted dyeing wastewater were used as carbon source. By a simple one-step hydrothermal method, the CDs with stimuli-responsive fluorescent chromotropic properties were obtained. With the addition of hydrochloric acid to the CDs solution, the emission of the CDs was red-shifted from 470 nm to 514 nm, and the fluorescence changed from blue to green. The phenomenon was attributed to the synergistic effect of more C O defects on the surface of CDs and the protonation of the carbonyl groups after adding acid. Based on acid-induced fluorescent chromotropic performance, we designed anti-counterfeiting labels for textiles and a double-switching information encryption anti-counterfeiting ink. This work synthesized responsive fluorescent CDs using waste dyes and showed great potential in the field of resource recycling. [Display omitted] [ABSTRACT FROM AUTHOR]

• PSSNa resins were prepared by the sulfonation reaction and acid-base reaction. • PSSNa resins showed a good adsorption capacity on MB. • PSSNa resins had good adsorption performance on alkaline dyes. The treatment of dye residue water pollution is a hot research topic, so it is necessary to prepare a resin which can adsorb dye efficiently. The sodium polystyrene sulfonate (PSSNa) were prepared by the sulfonation reaction of styrene resins with concentrated sulfuric acid and applied for Methylene Blue adsorption in wastewater. The structure of PSSNa was characterized by FT-IR, SEM, XPS and XRD. The results show that the maximum adsorption capacity is 16.89 mg∙ g −1. The adsorption processes of Methylene Blue with PSSNa conforms to the pseudo-second-order kinetic model and the Langmuir isotherm adsorption model, which means that the adsorption process follows single-molecular layer adsorption mechanism. The characteristic group (–SO 3 −) of the exchange resin interacts electrostatic with MB. Good desorption was achieved with 1 mol· L −1 HCl solution, and the resin retained good adsorption capacity after 5 adsorption-desorption cycles. In practical applications, PSSNa exhibits a good removal efficiency for dyes containing MB in lake water. These results provide a reference for the treatment of printing and dyeing wastewater by resin adsorption materials. [Display omitted] [ABSTRACT FROM AUTHOR]

A ZrO2 material was synthesized and optimized by the hydrothermal synthesis method with cetyltrimethylammonium bromide and ZrOCl2∙8H2O, and loaded Co and Mn bimetallic oxides to prepare the Co-Mn/ZrO2 catalyst via an incipient wetness impregnation process. In comparison with the analogous catalyst which supported by a commercial ZrO2, the catalyst displayed an excellent performance in the degradation of azo dye methyl orange (MO) solution via the catalytic ozonation process (COP), and the degradation efficiency of MO with 100 mg/L initial concentration would achieve 95.0% at room temperature, 1.0 mg/mL catalyst dosage, 0.65 mg/min O3 flow, and 60 min. A series of characterizations like scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, inductively coupled plasma optical emission spectroscopy (ICP-OES) and N2 adsorption–desorption was implemented, and showed that a larger Brunauer–Emmett–Teller reached 42.6 m²/g and elevated the outstanding dispersion of Co and Mn oxides on ZrO2, which accelerated the catalytic formation of hydroxyl radical from O3 during the COP. Moreover, the Co-Mn/ZrO2 catalyst was also investigated in the durability of catalytic MO degradation, which showed a slight diminishing trend by 6.9% for the degradation efficiency after four repetitive runs, and the loss of Co and Mn oxides from catalyst illustrated by the ICP-OES detection led to the catalyst deactivation. [ABSTRACT FROM AUTHOR]

Refractory organic pollutants in tail water of dyeing wastewater treatment have aroused wide concern. Their efficient and cost-effective removal reduced their threat to public health and ecosystem. Herein, a novel short-cut photocatalysis/algal degradation-based hybrid technology was implemented in efficient removal of methylene blue (MB) in simulated tail water using reliable titanium dioxide and common Chlorella pyrenoidosa, and the mechanisms in processes were emphasized. The treatment efficiency was significantly improved via pretreatment before chemical and biological degradation. MB of 79.71% was concentrated as the adsorption of the modified titanium dioxide and the collection of titanium dioxide by inorganic coagulant. The supernatant with low concentration of MB after coagulation was able to be directly treated by Chlorella pyrenoidosa. MB of 93.7% was degraded and transformed to intermediates in short-cut photocatalysis under visible light in 1 h. The intermediates owning the low biological inhibition were easily further degraded by Chlorella pyrenoidosa in 6 days. Mechanism analysis implied that the modified titanium dioxide was not simple monolayer adsorption, and physical adsorption was dominant. The coagulant played an essential role of charge neutralization in collection of the modified titanium dioxide. The removal of photocatalytic intermediates was divided to fast adsorption of Chlorella pyrenoidosa, low desorption in lag period of algae, and gradual biodegradation that accompanied with the increase of algal cell quantity. [ABSTRACT FROM AUTHOR]

Natural ferrous minerals are readily available and recyclable catalysts in photo-Fenton-like oxidation for wastewater treatment. In this work, typical ferrous oxide and sulfide minerals including magnetite, chalcopyrite, and pyrrhotite were exploited as catalysts in heterogeneous photo-Fenton oxidation for purification of biological effluent of dyeing wastewater. In a wide initial pH range (3.0~7.5), ferrous mineral-based heterogeneous photo-Fenton-like reactions were proven to be effective on the oxidation of recalcitrant pollutants. COD removals achieved 60.57%, 58.83%, and 57.41% using pyrrhotite, chalcopyrite, and magnetite, respectively, as catalyst under ultraviolet irradiation of 220~275 nm at H2O2 concentration of 9.8 mM. The corresponding COD removals were 51.75% and 34.09% with or without ferrous sulfate additions in UV/H2O2 systems. Minerals exhibited excellent stability and reusability with photo-catalytic activity reduction of less than 10% in the reuse of 5 cycles. Dissolved iron concentrations were determined to be 1.86 mg L−1, 4.62 mg L−1, and 7.53 mg L−1 for magnetite, chalcopyrite, and pyrrhotite, respectively, at pH 3 and decreased to zero in neutral pH environment, which were much lower than those required for homogenous Fenton reaction. It was deduced that oxidation of recalcitrant pollutants was mainly catalyzed by Fe(II) on the mineral surface. The more reactive oxygen species such as hydroxyl radicals were resulted from the reaction of surface Fe (II) with H2O2, H2O2 photolysis, and charge separation of minerals under UV irradiation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ca, an inexpensive alkaline earth metal, was doped into tetragonal β-In 2 S 3. • Ca doping narrowed the band gap and reduced charge transfer resistance of β-In 2 S 3. • The optimal Ca doped β-In 2 S 3 degraded 94.97% of Methyl Orange in 20 mins. • Abundant flaky structure endowed Ca doped β-In 2 S 3 with large surface area. • The photocatalytic mechanism for MO degradation over Ca doped β-In 2 S 3 was proposed. Photocatalytic technology can provide a clean, low-cost and highly efficient path to approach the degradation of azo dyes. Tetragonal β-In 2 S 3 possesses plenty of vacancies, furnishing dopants with abundant interspace, and can be used as a potential photocatalyst for dyes degradation. In this work, Ca was doped into β-In 2 S 3 via a facile one-pot hydrothermal method, which was mainly doped into the crystalline lattices of β-In 2 S 3. Ca doped β-In 2 S 3 revealed better photo-degradation of Methyl Orange (MO) than undoped β-In 2 S 3. The doped Ca ions narrowed band gap and acted as a charge transfer medium, leading to the wider light absorption range and smaller photogenerated charge transfer resistance, respectively. The optimum preparation condition of Ca doped β-In 2 S 3 was determined as holding temperature at 120 °C for 8 h, by which 94.97% of MO was degraded in 20 mins under visible light. The outstanding performance could be owed to the full-grown flaky structure with maximal specific surface area. Based on the experimental results, a possible photocatalytic mechanism for MO degradation over Ca doped β-In 2 S 3 was proposed. [ABSTRACT FROM AUTHOR]