Dye Wastewater Treatment Research Articles

Preparation and characterization of Ag3PO4@g-C3N4 photocatalysts for dye wastewater treatment under visible-light irradiation

Ag3PO4@g-C3N4 photocatalyst was successfully prepared via a workable liquid phase deposition strategy. The Ag3PO4 particles were anchored intimately on the surface of g-C3N4 by the chemical bonding interactions. The obtained Ag3PO4@g-C3N4 heterojunction catalysts exhibit outstanding enhanced photodegradation performance and good stability for the removal of organic pollutants rhodamine B (RhB) and methyl orange (MO). And the as-synthesized Ag3PO4@g-C3N4 also displayed excellent stability for the photodegradation activity of RhB and MO in wastewater, and the performance remained above 90% after six cycles. The significant improvement of photocatalytic performance is attributed to the hereojunction structures derived from the interaction between Ag3PO4 and g-C3N4. The mechanism of the photocatalytic removal of RhB and MO dye was also investigated by the capture experiments and ESR spectra. Based on the research results, a new simple and feasible way for the preparation of Ag3PO4@g-C3N4 photocatalyst is provided for the degradation of organic pollutants in wastewater.

In situ bridges of nano-titanium dioxide constructed in MXene self-cleaning loose nanofiltration membranes for dye wastewater treatment

It has been a longstanding problem to combat the oxidation process of MXene membranes. Here, we propose a strategy to construct nano bridge defect repair loose nanofiltration membrane with the help of MXene oxidation. The oxidation kinetics of Ti3C2Tx was investigated in both model and experimental aspects. The acid solution leads to aggregation and smaller d-spacing. However, the oxidation of MXene was accelerated in alkaline solution via reaction with hydroxyl anions resulting in a hydrophilic MXene membrane surface. The water permeability of the pH = 12-Ti3C2Tx membrane increased to a maximum value of 26.5 L·m−2·h−1·bar−1 together with a high rejection (98 %) of Janus green B (JGB). Titanium dioxide, which was in situ formed by oxidation of MXene, gives the membrane self-cleaning properties under UV light. The water recovery ratio was as high as 96.6 %. To further study the mechanism of in situ oxidation of MXene to form nano-titanium dioxide, the oxidation stages were analyzed which revealed that the in-situ oxidation process involved three different oxidations stages. This research offers a new perspective on MXene membrane design, paving the way for a new method of in situ nano bridge defect repair loose MXene nanofiltration membrane.

Room-temperature aqueous synthesis of MOF-808(Zr) for selective adsorption of dye mixtures

ZrIV-based metal–organic frameworks (MOFs) featuring distinguished water stability, large surface area, and intriguing functionalities have immense potential for practical usage. However, conventional MOF synthesis approaches generally require high reaction temperatures and organic solvents to initiate and template the nucleation and growth, hindering sustainable and cost-effective manufacturing and application of Zr-based MOFs. In this study, a scalable, room-temperature and aqueous synthesis of MOF-808—a Zr-MOF extensively explored as an adsorbent in both academic and industrial sectors—was reported. A rational use of water/formic acid (FA) as a green co-solvent enabled the formation of Zr6-cluster in an aqueous phase, thereby facilitating subsequent coordination with H3BTC to yield well-crystallized MOF-808. The effects of the water/FA volume ratio, the total solvent volume, and reaction time on the physicochemical properties of MOF-808 were studied. The optimized synthesis conditions (FA/water = 2.7:8.1, and reaction time = 24 h) resulted in the synthesis of MOF-808 with good hydrophilicity, excellent stability, high surface area, and weak positive charges. Moreover, this synthesis approach was successfully upscaled, yielding 11.5 g of MOF-808 at a magnification factor of 48. Notably, MOF-808-V10.8 exhibited an impressive adsorption capacity for Congo Red (ca. 1500 mg/g) and demonstrated selective fractionation of dye mixtures, suggesting their potential application in dye wastewater treatment. This methodology is expected to provide guidance for aqueous and scalable fabrication of Zr-MOFs towards water-related environmental applications.

Electrocatalytic Degradation of Rhodamine B on the Sb-Doped SnO2/Ti Electrode in Alkaline Medium.

To realize efficient electrocatalytic degradation of organic compounds in alkaline wastewater, an Sb-doped SnO2/Ti electrode was fabricated and employed for the removal of Rhodamine B (RhB), and the electrocatalytic oxidation performance of this electrode was assessed in an alkaline medium. In an alkaline solution (pH 11), the complete fading of 50 mg·L-1 RhB could be achieved after 150 min of degradation, the removal efficiency of the chemical oxygen demand reached 56.1% at 300 min, and the degradation process of RhB followed the pseudo-first-order kinetic model very well. Under the attack of hydroxyl radicals, partial RhB was degraded to low-molecular-weight organic acids through N-demethylation and the destruction of the conjugated chromophore. Various techniques including scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and cycle voltammetry were used to examine the changes in the morphology and structure, as well as the activity of the Sb-doped SnO2/Ti electrode before and after use. The Sb-doped SnO2/Ti electrode could be reproduced in batches, and each electrode was reused up to eight times without a significant decrease in degradation ability; the leaching amount of antimony was significantly lower than the national emission standard. The electrocatalytic oxidation of the dye wastewater sample was also performed with the desired results, indicating that electrochemical oxidation is a very promising technology for the treatment of alkaline dye wastewater using a Sb-doped SnO2/Ti electrode.

Properties and Mechanism of Fe–Cu–AC Microelectrolysis for Treatment of Typical Dye Wastewater

Properties and Mechanism of Fe–Cu–AC Microelectrolysis for Treatment of Typical Dye Wastewater

Prospects of green adsorbent produced from avocado seed via hydrothermal carbonization for treatment of dye wastewater

The adsorption process is a highly effective operational technique for dye removal from industrial wastewater. At present, the commercial adsorbents employed for removing dyes are manufactured via a slow pyrolysis process, which is time-consuming and requires more energy. Hydrothermal carbonization, on the other hand, is a highly efficient alternative method of synthesizing adsorbents that consumes less time and energy while producing effective adsorbents. This study synthesized adsorbents from avocado seeds via hydrothermal carbonization, followed by chemical activation. The adsorption study revealed that the avocado seed adsorbent has the highest color removal of 80 % using 3.5 g/L of adsorbent at acidic pH under optimized conditions. In conclusion, hydrochar from the avocado seed is a potential green adsorbent for the treatment of dye wastewater.

Photocatalytic treatment of landfill leachate using CaTiO3 nanoparticles

Perovskite Calcium titanate (CaTiO3)is a versatile material that can be used in several applications, such as biomedicine, electronic devices, photocatalysis, and wastewater treatment.In this study, CaTiO3nanoparticles were synthesized using the sol–gel method at 600 °C with the help of tetra butyl titanate, calcium nitrate, and citric acid as chelating agents. FESEM and TEM analysis shows the synthesized nanoparticle has particle sizes of less than 26.23 and 23.71 nm respectively with a bandgap of 3.57 eV. By using DTA, TGA, XRD, FESEM, TEM, EDX, and UV–Vis, the thermal, structural, and optical properties were examined. Several studies examined the photocatalytic capabilities of CaTiO3for the photocatalytic treatment of simulated dye solution and wastewater produced by the textile industry. In this study, the CaTiO3 nanoparticles are used in the photocatalytic treatment of landfill leachate. The results are promising, showing a 72 % reduction in chemical oxygen demand (COD),a 43.62 % decrease in colour,a 41.75 % improvement in turbidity, 59.01 % removal of total dissolved solids, and35.71 % removal of NH3-N from the landfill leachate under the optimum condition of 33 W UV irradiation for 8 h at a catalyst dose of 3.33 g/L and a pH of 6. After nano-photocatalytic treatment, the percentages of Cr, Ni, and Zn removed are 52.30 %, 63.46 %, and 87.50 %, respectively.

The effectiveness of using coconut husk powder as an adsorbent to enhance the wastewater quality of the cepuk textile industry in Nusa Penida, Bali, Indonesia

Introduction: Tenun Cepuk (traditional woven) from Nusa Penida holds great potential as a traditional textile art form, cherished for its intricate patterns and cultural significance. However, the textile industry's wastewater, with its dye-related pollution, presents a significant environmental challenge that needs sustainable solutions. Coconut husk powder exhibits promising potential as an adsorbent for treating dye wastewater from the textile industry. Investigating the interplay between varying thicknesses and contact durations is crucial to maximizing coconut husk powder's adsorption capacity and efficiency for dye wastewater treatment. Method: This study, following an Experimental research design with a Posttest Only Control Group Design, aims to assess the impact of an intervention on the experimental group compared to the control group. Coconut fibers, sourced from Nusa Penida agriculture, serve as the adsorbent. Coconut powder is added to these tanks at thicknesses of 5 cm, 10 cm, and 15 cm. Subsequently, wastewater samples from the Cepuk weaving process are introduced into each experimental tank, along with a control group. The process is left for 24 and 72 hours as varying contact times. The adsorption results are subjected to analysis for parameters, including total suspended solids (TSS), total dissolved solids (TDS), five-day biochemical oxygen demand (BOD5), and chemical oxygen demand (COD) at the Panureksa Denpasar Laboratory. Results: The use of coconut husk powder as an adsorbent effectively lowers TDS, TSS, BOD5, and COD in Cepuk textile dye wastewater. The reduction depends on adsorbent thickness and contact time. Thicker adsorbents notably reduce TDS, TSS, BOD5, and COD, enhancing wastewater quality and environmental safety. A 15 cm-thick adsorbent effectively reduces TDS to permissible levels. Prolonged contact times also significantly lower levels. Conclusion: Coconut husk powder can be utilized to decrease TDS, TSS, BOD5, and COD levels in textile dye wastewater. Thickness and contact time significantly impact the enhancement of wastewater quality.

Azo dye wastewater treatment in a novel process of biofilm coupled with electrolysis

Azo dye wastewater treatment in a novel process of biofilm coupled with electrolysis

Constructing mesoporous biochar derived from waste carton: Improving multi-site adsorption of dye wastewater and investigating mechanism

The development of cost-efficient biochar adsorbent with a simple preparation method is essential to constructing efficient wastewater treatment system. Here, a low-cost waste carton biochar (WCB) prepared by a simple two-step carbonization was applied in efficiently removing Rhodamine B (RhB) in aqueous environment. The maximum ability of WCB for RhB adsorption was 222 mg/g, 6 and 10 times higher than both of rice straw biochar (RSB) and broadbean shell biochar (BSB), respectively. It was mainly ascribed to the mesopore structure (3.0–20.4 nm) of WCB possessing more spatial sites compared to RSB (2.2 nm) and BSB (2.4 nm) for RhB (1.4 nm✕1.1 nm✕0.6 nm) adsorption. Furthermore, external mass transfer (EMT) controlled mass transfer resistance (MTR) of the RhB sorption process by WCB which was fitted with the Langmuir model well. Meanwhile, the adsorption process was dominated by physisorption through van der Waals forces and π-π interactions. A mixture of three dyes in river water was well removed by using WCB. This work provides a straightforward method of preparing mesoporous biochar derived from waste carton with high-adsorption capacity for dye wastewater treatment.

Polyethylene terephthalate cap‐based bioreactors for combined domestic and dye wastewater treatment

AbstractIn the current study, a sequencing batch reactor (SBR), a sequencing batch biofilm reactor (SBBR) and a moving bed biofilm reactor (MBBR) were designed and used to treat actual samples of combined domestic and dye (Congo red) wastewaters over a 10‐hour cycle. A new application of reusing plastic bottle caps in the SBBR and MBBR was examined. In the SBR, maximum chemical oxygen demand (COD) removal of up to 66% ± 3% was achieved after nine cycles of operation. In the SBBR, a rapid increase in COD removal efficiency was observed during the first cycle, with a noticeable improvement in performance in subsequent cycles, eventually reaching a maximum COD removal efficiency of 77% ± 3%. In the MBBR, maximum COD removal of up to 88% ± 3% was achieved after nine cycles of operation. The biodegradation occurred during two phases in the SBR and SBBR, as an anaerobic phase in the first 2 hours and then as an aerobic phase in the last 8 hours of operation; the MBBR operated in the fully saturated aerobic phase for 10 hours. Of the three reactors used, results for the MBBR in the fully aerobic condition by using polyethylene terephthalate caps as a biocarrier, demonstrated the optimum conditions under which to treat and biodegrade Congo red at all concentration in each cycle. The maximum removal efficiency, which equalled 99% ± 1%, was recorded at an optimal concentration of 50 mg/L. Additionally, five kinetic models were proposed to assess microbial growth activity, and the results demonstrated the elimination of toxic effects when using polyethylene terephthalate caps as biocarriers in the MBBR. The laboratory experiments were consistent with the Monod model.

Preparation of solvent-resistant polyimide membranes for efficient separation of dyes and salts via an “internal drive” strategy

It is extremely difficult to separate salts and dyes from high-salinity printing and dyeing wastewater. In this study, modified montmorillonite (EPTAC-CD-MMT) was obtained by intercalation of 2,3-epoxypropyltrimethylammonium chloride (EPTAC) modified cyclodextrin (CD). PI/EPTAC-CD-MMT membrane was prepared by blending EPTAC-CD-MMT with polyimide (PI). The addition of EPTAC-CD-MMT could inhibit the motion of PI molecular chains and increase the solvent resistance of the membrane. Additionally, EPTAC-CD-MMT exhibited spontaneous “internal drive” during the phase transition and segregated to the membrane surface. The pore structure of the membrane was adjusted to a well-developed “side pore” structure. Thus, solvent-resistant membranes for dye/salt separation with high flux were finally obtained. The successful modification of MMT was demonstrated by FTIR, XRD, TGA and XPS. EDX and SEM were used to characterize the surface segregation phenomena and well-developed pore structures of the membranes. When EPTAC-CD-MMT was added at 3 wt%, the membranes showed a significant increase in pure water flux (138.0 L·m−2·h−1·bar−1), high dye rejection (>98.5 %), low salt rejection (<10.0 %), and good solvent resistance in six organic solvents. This demonstrated the potential of PI/EPTAC-CD-MMT separation membranes for the treatment of dye wastewater containing sophisticated organic solvents.

Ultrasound assisted electrochemical oxidation of synthetic dye wastewater

ABSTRACT This study reports the treatment of synthetic dye wastewater in a sono-electrochemical reactor. The influence of three different supporting electrolytes (Na2SO4, NaCl, and Na2NO3) on % decolorisation was studied and higher decolorisation was observed with NaCl. The increase in applied current density (0.25, 0.5, 0.75, 1, 1.25 A/dm2) enhanced the color removal and the optimum current density arrived was 1.25 A/dm2. The % decolorisation was studied at three different pH (3, 7 & 11), and about 95.7% decolorisation was observed at pH 3. The inter electrode distance of 1 cm gave highest decolorisation. The addition of Na2SO4 and Na2NO3 in the sonolyzer bath did not influence the % decolorisation significantly. The sono-electrochemical process gave 99.16% decolorisation and 91.15% COD reduction while the electrochemical process gave 94.79% decolorisation and 76.82% COD reduction. The optimum electrolyte concentration, current density, pH and electrode distance of 0.5 g/L, 1.25 A/dm2, 3, and 1 cm, respectively gave highest decolorisation. The reaction kinetics of the sono-electrochemical oxidation treatment was also investigated. The higher mineralisation rate at a lower residence time indicates that the combined treatment is promising for degrading recalcitrant compounds present in wastewater.

UV‐initiated preparation and absorption properties of pseudo‐polyrotaxane cyclodextrin‐based PVA/poly (acrylamide‐co‐acrylic acid) hydrogel

AbstractThe recycling of dyes from dye wastewater is one of the most challenging problems in wastewater treatment. In this study, a pseudo‐polyrotaxane cyclodextrin based PVA/poly (acrylamide‐co‐acrylic acid) hydrogel was prepared by UV‐initiated polymerization. The network structure of the hydrogel and the performance on the dye absorption were adjusted by controlling the content of cyclodextrin. The study was mainly focused on the absorption of methylene blue (MB) in different environments, selectivity of absorption in mixed solutions and the cyclic absorption behavior. At room temperature, the absorption efficiency of this hydrogel for MB and methylene green reached 91.37% and 94.23%, respectively. In addition, the hydrogel exhibited highly selective absorption towards MB in mixed dye solutions. In the absorption‐desorption cyclic experiments, a more cost‐effective and environmental friendly solvent, a mixture of ethanol and water, was used, and after ten cycles, the highest absorption efficiency was basically maintained. Hence, the hydrogel is expected to be a candidate for more efficient and economical absorbent material in dye wastewater treatment.

Facile synthesis of Ag2CO3/Ag2O@NiFe LDH nanohetrostructure with enhanced photocatalytic performance for MB dye degradation under visible light irradiation

The photocatalyst Ag2CO3/Ag2O@NiFe LDH nanocomposite was synthesized successfully by a facile co-precipitation method followed by hydrothermal treatment. The as-prepared photocatalyst demonstrated excellent physicochemical and optical properties using various characterization techniques. It was found that the photodegradation performance of NiFe LDH for MB dye removal can be significantly improved by appropriate Ag incorporation. The optimal composite which had a 0.75 Ag molar ratio demonstrated superior degradation performance for MB dye reaching 99.5%. The degradation efficiency was three times higher compared to pure NiFe LDH. Additionally, the apparent rate constant (0.028 min−1) was approximately 28 times greater than that of the pure LDH (0.001 min−1). After 5 successive cycles, the composite exhibited 73% degradation efficiency reflecting its high photostability throughout the regeneration process. The synthesized photocatalyst exhibited exceptional properties, indicating its promising potential for industrial applications in the treatment of dye wastewater.

Preparation of 1,8-dichloroanthraquinone/graphene oxide/poly (vinylidene fluoride) (1,8-AQ/GO/PVDF) mediator membrane and its application to catalyzing biodegradation of azo dyes

Anthraquinone is a redox mediator that can effectively catalyze the degradation of azo dyes by promoting the electron transfer. In this study, a mediator membrane with poly (vinylidene fluoride) (PVDF) as the membrane support and 1,8-dichloroanthraquinone (1,8-AQ) and graphene oxide (GO) as the additives was prepared and characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), mercury intrusion porosimetry (MIP), atomic force microscopy (AFM) and water contact angle. The introduction of GO increases the pure water flux of the membrane to 258.56±12.93 L/(m2·h). Its catalytic performances for the biodegradation of azo dyes were evaluated. Under the optimized conditions, the 1,8-AQ/GO/PVDF composite membrane is able to improve the dye degradation efficiency 2.2 times for reactive red X-3B and 1.1 times for acid red B, as compared with PVDF membrane. In addition, the mediator membrane maintains stable and high catalytic efficiency in the cyclic test and over 90 % dye degradation efficiency is still obtained after 5 cycles of decolorization. These results suggest the great application potentials of the 1,8-AQ/GO/PVDF membrane in the dye wastewater treatment.

Toward Climate Neutrality: A Comprehensive Overview of Sustainable Operations Management, Optimization, and Wastewater Treatment Methods

Various studies have been conducted in the fields of sustainable operations management (SOM), optimization, and wastewater treatment, yielding unsubstantiated recovery. In the context of Europe’s climate neutrality vision, this paper reviews effective decarbonization strategies and proposes sustainable approaches to mitigate carbonization in various sectors such as buildings, energy, industry, and transportation and how these interlink with wastewater management. The study also explores the role of digitalization in decarbonization and reviews policies that can direct governments’ actions towards a climate-neutral society. This paper presents a review of optimization approaches applied in the fields of science and technology, incorporating modern optimization techniques based on various peer-reviewed published research papers. It emphasizes non-conventional energy and distributed power-generating systems along with the deregulated and regulated environment. Additionally, this paper critically reviews the performance and capability of the micellar-enhanced ultrafiltration (MEUF) process in the treatment of dye wastewater. The review presents evidence of the simultaneous removal of co-existing pollutants and explores the feasibility and efficiency of biosurfactants instead of chemical surfactants. Lastly, the paper proposes a novel Firm–Regulator–Consumer-Technology Enablers/Facilitators interaction framework to study operations, decisions and interactive cooperation considering the relationships between the four agents through a comprehensive literature review of SOM. The proposed framework provides support for exploring future research opportunities and holistic sustainability initiatives.

Facile preparation of graphene oxide-based composite aerogel to efficiently adsorb methylene blue

With acrylamide (AM), diethylenetriaminepentaacetic acid (DTPA), chitosan (CS), and graphene oxide (GO) as the raw materials, a GO-based composite aerogel named as APAM/DTPA-CS/GO (APAM = Anionic polyacrylamide) was constructed by a facile method. The composite aerogel was systematically characterized by scanning electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction to confirm the successful preparation. Methylene blue (MB) was used as the model dye molecule to evaluate the adsorption behaviors of APAM/DTPA-CS/GO. The results showed that equilibrium adsorption capacity of the aerogel toward MB could attain 652.99 mg/g at 303 K, which was more efficient than many previously reported adsorbents. The main driving forces of adsorption process were electrostatic interaction, hydrogen bond, and π-π conjugate interaction. The adsorption process of MB by the composite aerogel could be well described by pseudo-second-order kinetic model and Langmuir isothermal model. APAM/DTPA-CS/GO still maintained high equilibrium adsorption capacity of more than 600 mg/g toward MB even after six adsorption-desorption cycles, indicating that the aerogel had excellent regenerability. The efficient and recyclable adsorption performances might endow GO-based composite aerogel with considerable application prospect in the treatment of dye wastewater.

Synergistic effect between montmorillonite and imidazolium-functionalized carboxylate-based polyelectrolyte for enhancing the removal of methylene blue

The composite of montmorillonite (Mt) and novel imidazolium-functionalized carboxylate-based polyelectrolyte (P(NaAA/VIC)) was formed through the bridging interaction of zwitterionic groups, enabling efficient and rapid removal of industrial cationic dye methylene blue (MB) from aqueous solution. The removal rate of pure P(NaAA/VIC) was difficult to reach 90%, while P(NaAA/VIC)/Mt composites achieved the removal rate of more than 95%. The substantial improvements of removal rate were attributed to the formation of larger adsorbed aggregates, facilitating easy separation. Importantly, Mt laminae, as a rigid structure, could effectively prevent molecular chain of polyelectrolyte curling due to electrostatic shielding after adsorption, which made the adsorption sites play a full role, thus enhancing the adsorption efficiency. The maximum adsorption capacity of composite (80 wt% P(NaAA/VIC) and 20 wt% Mt) was increased by about 20% compared with pure P(NaAA/VIC). And the excessive zwitterionic groups in polyelectrolyte would lead to a decrease in adsorption capacity. The systematic investigation revealed that the adsorption was a spontaneous exothermic process driven by electrostatic interactions, conforming to the pseudo-second-order kinetic model, in which the adsorption was monolayer coverage. The composite can achieve an high adsorption capacity of 1381.7 mg/g at 20 °C, demonstrating enormous potential in the treatment of cationic dye wastewater.

Low-temperature plasma-induced porous Sb2WO6 microspheres with rich oxygen vacancies to promote high-performance photocatalytic activity

The escalating issue of water pollution has sparked significant attention among researchers in the field of photocatalysis. Consequently, it holds immense significance to develop photocatalysts that exhibit high charge separation efficiency and stability for effectively degrading pollutants in water. In this study, OV-Sb2WO6-X photocatalyst was synthesized by incorporating oxygen vacancies into pristine Sb2WO6. The introduction of oxygen vacancies significantly enhanced the charge separation efficiency, resulting in a substantial improvement in the photocatalytic activity. The content of oxygen vacancies was controlled by plasma treatment time, processed for 10, 20 and 30 min, and electron paramagnetic resonance (EPR) test demonstrated the introduction of oxygen vacancies successfully. Furthermore, X-ray photoelectron spectroscopy (XPS) characterized the internal electron flow direction of the photocatalyst. OV-Sb2WO6-20 showed the degradation rate of Rhodamine B (RhB) that nine times of the Sb2WO6, while the Tetracyclines (TC) degradation rate showed 3.5 times that of Sb2WO6. Moreover, OV-Sb2WO6-20 exhibited superior stability in terms of recycling activity and material structural integrity. Additionally, free radical trapping experiments and electron spin-resonance spectroscopy characterization demonstrated that h+ played a crucial role as the reactive species during the degradation process. This research presents a viable approach for the modification of Sb2WO6-based materials, enabling effective treatment of dye wastewater and achieving successful purification.