Search

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.

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.

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.

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.

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.

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.;

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.

A pilot-scale six-compartment hybrid anaerobic baffled reactor (HABR) with effective volume of 18 m3 was used to treat dyeing wastewater. The HABR system was able to treat the wastewater efficiently after FeSO4 pretreatment, as indicated by removal efficiencies of 33.7% for chemical oxygen demand (COD), 39.9% for suspended solid (SS), and 22.5% for sulfate (SO42−) during steadily operational period. Gas chromatography–mass spectrometry (GC-MS) showed that the concentrations of alkanes, amides, organic acids, ketones, phenols, and esters were much lower in the effluent than those in the influent; many high-molecular-weight compounds such as cyclanes, quinolines, and phenols were successfully transformed to low-molecular-weight ones. As illustrated from the results of generalized grey relational analysis (GGRA), COD removal efficiency was more closely associated with flow rate, organic loading rate (OLR), water temperature, and influent SS among the whole selected possible factors. Based on the overall treating effectiveness and the GGRA study, the optimized operation strategy of the dyeing wastewater treatment by HABR was obtained as the hydraulic retention time (HRT) of 12 h for steady-state operation with an up-flow velocity of 1.7 m/h as well as OLR of 1.5–2.0 kg COD/(m3·d).

A homogeneous ferrous salt catalyst was used in the traditional Fenton oxidation technology for dyeing wastewater. However, it was difficult to avoid the secondary pollution and loss of ferrous ions. Zeolite catalysts, which are more efficient and environmentally friendly than conventional catalysts, have good prospects in the field of catalytic oxidation of dyeing wastewater. In this article, Fe-ZSM-5 zeolite catalyst was prepared by the liquid ion exchange method to replace the traditional ferrous salt catalyst and its catalytic effect was studied for wastewater treatment with the Fenton reagent. X-ray Diffraction was applied to study the characteristics of the Fe-ZSM-5 zeolite catalyst. The result indicated that the Fe-ZSM-5 well reserved the structures of a molecular sieve, which improved the catalytic effect. The effect of the number of ion exchanges and supported Fe on the structure of ZSM-5 zeolite is discussed in this paper. The treatment of dyeing wastewater by catalyzer of Fe-ZSM-5 and oxidant of H2O2 has been investigated under the optimal conditions of temperature, pH value, dosage of Fe-ZSM-5 and reaction time. Results show that Fe-ZSM-5 zeolite catalyst has excellent catalytic effect and the decolorization rate of the dye was to 98.5% under optimal conditions. The catalytic effect of the heterogeneous Fe-ZSM-5 was 3% higher than that of the traditional Fenton oxidation technology. Moreover, the residuals of Fe were significantly different between the two methods, which demonstrate that the heterogeneous Fe-ZSM-5 catalyzer efficiently overcame the problems of the catalyzer loss and secondary pollution.

Wastewater from the Batik textile industry contains large amounts of dyestuff together with significant amounts of suspended solids (SS), dispersing agents, salts and trace amounts of metals. Since this can lead to severe environmental problems, proper wastewater treatment processes are essential. The synthesis of Fe3+ by sol-gel method doped on a ceramic foam for reactive red and disperse dyes removal from synthetic dye wastewater. In this research, the effect of color concentration, amount of catalyst and volumetric flow rates for industrial scale were studied. The Fe3+ catalyst was prepared by sol-gel method in which 3M of FeCl3 was used as a precursor. The synthesized catalyst was characterized by the EDX spectrum from an X-ray spectrometer. The surface morphology of the catalyst was investigated using a scanning electron microscope (SEM). To determine optimum operating conditions for catalytic testing, variations of disperse and reactive red concentrations (10 to 200 mg L-1) were used. The results indicated that the highest color removal efficiency (up to 96%) was observed when using Fe3+ catalyst; 4 pieces per liter of solution, and initial pH of 6.0. These conditions were then scaled up for a continuous packed bed column study. It was found that the optimal operating conditions obtained from the mathematical model for reactive red wastewater were: concentration of reactive red in the synthetic wastewater 20 to 80 mg L-1; amounts of catalyst 432.5 to 1,730 mg and volumetric flow rates of wastewater 20 to 200 mL min-1. Up to 84.85% of color removal efficiency was achieved.

Wastewater from the Batik textile industry contains large amounts of dyestuff together with significant amounts of suspended solids (SS), dispersing agents, salts and trace amounts of metals. Since this can lead to severe environmental problems, proper wastewater treatment processes are essential. The synthesis of Fe3+ by sol-gel method doped on a ceramic foam for reactive red and disperse dyes removal from synthetic dye wastewater. In this research, the effect of color concentration, amount of catalyst and volumetric flow rates for industrial scale were studied. The Fe3+ catalyst was prepared by sol-gel method in which 3M of FeCl3 was used as a precursor. The synthesized catalyst was characterized by the EDX spectrum from an X-ray spectrometer. The surface morphology of the catalyst was investigated using a scanning electron microscope (SEM). To determine optimum operating conditions for catalytic testing, variations of disperse and reactive red concentrations (10 to 200 mg L-1) were used. The results indicated that the highest color removal efficiency (up to 96%) was observed when using Fe3+ catalyst; 4 pieces per liter of solution, and initial pH of 6.0. These conditions were then scaled up for a continuous packed bed column study. It was found that the optimal operating conditions obtained from the mathematical model for reactive red wastewater were: concentration of reactive red in the synthetic wastewater 20 to 80 mg L-1; amounts of catalyst 432.5 to 1,730 mg and volumetric flow rates of wastewater 20 to 200 mL min-1. Up to 84.85% of color removal efficiency was achieved.

Wastewater from the Batik textile industry contains large amounts of dyestuff together with significant amounts of suspended solids (SS), dispersing agents, salts and trace amounts of metals. Since this can lead to severe environmental problems, proper wastewater treatment processes are essential. The synthesis of Fe3+ by sol-gel method doped on a ceramic foam for reactive red and disperse dyes removal from synthetic dye wastewater. In this research, the effect of color concentration, amount of catalyst and volumetric flow rates for industrial scale were studied. The Fe3+ catalyst was prepared by sol-gel method in which 3M of FeCl3 was used as a precursor. The synthesized catalyst was characterized by the EDX spectrum from an X-ray spectrometer. The surface morphology of the catalyst was investigated using a scanning electron microscope (SEM). To determine optimum operating conditions for catalytic testing, variations of disperse and reactive red concentrations (10 to 200 mg L-1) were used. The results indicated that the highest color removal efficiency (up to 96%) was observed when using Fe3+ catalyst; 4 pieces per liter of solution, and initial pH of 6.0. These conditions were then scaled up for a continuous packed bed column study. It was found that the optimal operating conditions obtained from the mathematical model for reactive red wastewater were: concentration of reactive red in the synthetic wastewater 20 to 80 mg L-1; amounts of catalyst 432.5 to 1,730 mg and volumetric flow rates of wastewater 20 to 200 mL min-1. Up to 84.85% of color removal efficiency was achieved.

Wastewater from the Batik textile industry contains large amounts of dyestuff together with significant amounts of suspended solids (SS), dispersing agents, salts and trace amounts of metals. Since this can lead to severe environmental problems, proper wastewater treatment processes are essential. The synthesis of Fe3+ by sol-gel method doped on a ceramic foam for reactive red and disperse dyes removal from synthetic dye wastewater. In this research, the effect of color concentration, amount of catalyst and volumetric flow rates for industrial scale were studied. The Fe3+ catalyst was prepared by sol-gel method in which 3M of FeCl3 was used as a precursor. The synthesized catalyst was characterized by the EDX spectrum from an X-ray spectrometer. The surface morphology of the catalyst was investigated using a scanning electron microscope (SEM). To determine optimum operating conditions for catalytic testing, variations of disperse and reactive red concentrations (10 to 200 mg L-1) were used. The results indicated that the highest color removal efficiency (up to 96%) was observed when using Fe3+ catalyst; 4 pieces per liter of solution, and initial pH of 6.0. These conditions were then scaled up for a continuous packed bed column study. It was found that the optimal operating conditions obtained from the mathematical model for reactive red wastewater were: concentration of reactive red in the synthetic wastewater 20 to 80 mg L-1; amounts of catalyst 432.5 to 1,730 mg and volumetric flow rates of wastewater 20 to 200 mL min-1. Up to 84.85% of color removal efficiency was achieved.