High Removal Efficiency Research Articles

The Study of Nitrogen and Phosphorus Removal Efficiency in Urbanized River Systems Using Artificial Wetland Systems with Different Substrates

This study evaluated the effectiveness of five commercial substrates (zeolite, volcanic rock, gravel, magic rack, and ceramic pellets) in removing nitrogen (N) and phosphorus (P) from urban river systems using constructed wetlands. By employing X-ray CT and NGS technologies, we analyzed the physical structure of the substrates and the microbial communities they harbor. The results indicated that volcanic rock and ceramic pellets, due to their high porosity and specific surface area, performed exceptionally well in nitrogen and phosphorus removal. Specifically, the microbial systems with these two substrates achieved ammonia nitrogen removal rates of 89.86% and 88.45%, total nitrogen removal rates of 78.78% and 74.97%, and total phosphorus removal rates of 92.67% and 80.82%, respectively, within a 7-day period. Furthermore, the microbial communities on volcanic rock and ceramic pellets were more diverse, which correlated with their high pollutant removal efficiency. The study further elucidated the synergistic role of substrate characteristics and microbial community structure and function in nitrogen and phosphorus removal, enhancing the understanding of the purification mechanisms in constructed wetlands. These findings provide a scientific basis for the ecological restoration of urban rivers and are significant for improving the quality of urban water environments.

Fabrication of CaCO3 Microcubes and Mechanistic Study for Efficient Removal of Pb from Aqueous Solution

Pb(II) contamination in aquatic environments has adverse effects on humans even at a low concentration, so the efficient removal of Pb at a low cost is vital for achieving an environmentally friendly, sustainable, and healthy society. A variety of CaCO3-based functional adsorbents have been synthesized to remove Pb, but the adsorption capacity is still unsatisfactory. Herein, calcite CaCO3 microcubes/parallelepipeds are synthesized via simple precipitation and a hydrothermal approach and found to outperform previously reported nano-adsorbents considerably. The CaCO3 achieves a high removal efficiency for Pb(II) (>99%) at a very low dosage (0.04–0.1 g/L) and an initial Pb(II) concentration of 100 mg/L. The CaCO3 presents an excellent adsorption capacity of 4018 mg/g for Pb(II) removal and depicts good stability over a wide range of pH 6–11. The maximum adsorption kinetics are fitted well by the pseudo-second-order kinetic model, whereas the Freundlich isotherm delineates the adsorption data at equilibrium well, indicating a multilayer adsorption process. The ex situ study confirms that the Pb(II) adsorption mechanism by CaCO3 can be attributed to the rapid metal-ion-exchange reaction between Pb(II) and Ca2+. Furthermore, a red shift in the Fourier Transform Infrared (FTIR) spectroscopy peak from 1386 cm−1 to 1374 cm−1 of CaCO3 after Pb removal indicates the adsorption of Pb onto the surface. This adsorbent provides an opportunity to treat wastewater and can be extended to remove other toxic heavy metals.

Innovative Strategies for Tannery Wastewater Remediation with Sequential batch reactor and phycoremediation

<p style="line-height:150%;text-align:justify;"><span style="font-family:"Times New Roman",serif;font-size:12.0pt;" lang="EN-IN">This research assessed the performance of combining Sequential Batch Reactor (SBR) and phycoremediation method used for tanning effluent. The SBR system obtained high removal efficiencies with Chemical Oxygen Demand (COD)  is reduced by  85%, Biological Oxygen Demand (BOD) is reduced  by 80% as well as ammonia by more than 75%. Chromium and lead were dropped by 65% and 60% correspondingly after treatment. Following SBR process, inclusion of Chlorella vulgaris in the phycoremediation stage further improves the removal of pollutants achieving 95% COD and 92% BOD reductions. Heavy metal removal was enhanced with chromium and lead by reducing 85% each. Kinetic analysis indicated that ammonia and COD removal followed first-order kinetics with high model fit (R2=0.93 for COD; R2=0.91 for ammonia). Heavy metal removal using Chlorella vulgaris also conformed to first-order kinetics. A temporary increase in ammonia levels was observed due to nitrification inhibition during periods of high organic loads in the wastewater discharged from tanneries into rivers or lakes without treatment facilities such as oxidation ditches or stabilization ponds used in some cases. Finally, it can be concluded that an integrated SBR phycoremediation process shows very good potentialities with respect to good performances in treating wastewater efficiently.</span></p>

The Degradation of Furfural from Petroleum Refinery Wastewater Employing a Packed Bubble Column Reactor Using O3 and a CuO Nanocatalyst

Furfural is one of the main pollutant materials in petroleum refinery wastewater. This work used an ozonized bubble column reactor to remove furfural from wastewater. The reactor applied two shapes of packing materials and two dosages of CuO nanocatalyst (0.05 and 0.1 ppm) to enhance the degradation process. The results indicated that adding 0.1 ppm of nanocatalyst provided an efficient rate of furfural degradation compared to that of 0.05 ppm. Also, the packing materials enhanced the furfural degradation significantly. As a result, the contact area between the gas and liquid phases increased, and a high furfural removal efficiency was achieved. It was found that the CuO nanocatalyst generated more (OH•) radicals. At a treatment time of 120 min and an ozone flow of 40 L/h, the furfural degradation recorded values of 80.66 and 78.6% at 10 and 20 ppm of initial concentration, respectively. At 60 ppm, the degradation efficiency did not exceed 74.16%. Furthermore, the kinetic study indicated that the first-order mechanism is more favorable than the second-order mechanism, representing the furfural degradation with a correlation factor of 0.9837. Finally, the furfural reaction can be achieved successfully in a shorter time and at low cost.

Facile Synthesis of Polypyrrole-Decorated RGO-CuS Nanocomposite for Efficient Nickel Removal from Wastewater

Efficient wastewater treatment, particularly the removal of heavy metal ions, remains a challenging priority in environmental remediation. This study introduces a novel sandwich-structured nanocomposite, RGO-CuS-PPy, composed of reduced graphene oxide (RGO), copper sulfide (CuS), and polypyrrole (PPy), synthesized via a straightforward hydrothermal method. The unique combination of RGO, CuS, and PPy offers enhanced adsorption capacity for Ni(II) ions due to RGO’s high surface area and CuS’s active binding sites, supported by PPy’s structural stability contributions. This study is among the first to explore this specific nanocomposite architecture for Ni(II) removal, achieving an adsorption capacity of 166.67 mg/g and a high removal efficiency of 94.9% within 210 min for 55 mg/L of Ni(II) concentration at pH 6 and adsorbent dose of 3 mg/15 mL. The kinetic analysis shows the best fitted time-dependent experimental data with the pseudo-second-order model, indicating chemisorption. Isotherm studies confirmed the Langmuir model as the best fit, yielding a high monolayer adsorption capacity of 166.67 mg/g. Thermodynamic analysis shows the adsorption process was endothermic (ΔH° = 80.23 kJ/mol) and spontaneous (ΔG° ranging from −6.985 to −14.399 kJ/mol). Additionally, reusability tests using 0.1 M HCl for desorption demonstrated good reusability, emphasizing the RGO-CuS-PPy nanocomposite’s potential as a sustainable adsorbent for Ni(II) removal in wastewater treatment applications.

A Review on Various Techniques for Boron Recovery: Focusing on Efficiency, Sustainability, Scalability, and Cost-Effectiveness

Boron is a critical element extensively used across various industries—such as glass manufacturing, ceramics, agriculture, detergents, nuclear energy, and aerospace—due to its unique chemical and physical properties. However, its widespread industrial use has raised significant environmental concerns, particularly its accumulation in aquatic systems, posing risks to biodiversity, plant life, and human health. This review examines the impacts of boron pollution on aquatic organisms, plants, and humans, highlighting the necessity for effective recovery strategies. We provide a comprehensive analysis of boron recovery techniques—such as reverse osmosis, electrodialysis, nanofiltration, adsorption, membrane distillation, and leaching—focusing on their efficiency, sustainability, scalability, and cost-effectiveness. The evaluation compares each method’s operational parameters, environmental impact, and economic feasibility. While methods like reverse osmosis and electrodialysis offer high removal efficiencies, they are often limited by operational costs and environmental drawbacks. Alternative methods like adsorption and nanofiltration present more sustainable and cost-effective options but may require optimization for large-scale applications. This review underscores the need for advanced, economically viable, and sustainable boron recovery technologies to mitigate environmental risks and comply with regulatory standards.

Preparation of Bi2CrO6/CuO heterostructure nanocomposite to increase methylene blue decomposition under visible light irradiation

In this study, the Bi2CrO6/CuO nanocomposite was used for the photocatalytic degradation of methylene blue (MB) under visible light. Nanocomposites with different ratios (1:1, 1:2, 2:1) were synthesized under hydrothermal conditions and investigated for MB removal. Various characterization techniques, including XRD, FT-IR, FE-SEM, BET, DRS, PL, and EDS, were employed to elucidate the physicochemical aspects of the catalysts. The 2:1 nanocomposite ratio was selected as the photocatalyst with the highest removal efficiency (85 %). Four main factors, including initial concentration, solution pH, catalyst dose, and light intensity, were studied using the response surface methodology (RSM) and the Box-Behnken model. Under optimal conditions, the MB removal efficiency reached 90.06 %. Additionally, the effect of oxidizing agents (H2O2) on the enhanced removal of MB was investigated. The improved photocatalytic performance of the Bi2CrO6/CuO (2:1) nanocomposite is attributed to visible light absorption, the formation of a p-n heterostructure, efficient charge separation via the S-scheme mechanism, and increased charge carrier lifetime. Moreover, economic calculations showed that the estimated costs for the photocatalytic removal of MB from wastewater are cost-effective.

Innovative Antifungal Photocatalytic Paint for Improving Indoor Environment

Indoor air quality (IAQ) has emerged as a global concern due to the increasing presence of indoor pollutants, which have been shown to negatively impact public health. These pollutants stem from various household activities and the materials used in buildings. Previous studies have explored several methods to improve IAQ, including gas adsorption, ozonation, non-thermal plasma, and photocatalytic oxidation (PCO). However, these methods often have drawbacks, such as generating secondary pollutants or incurring high costs. This study examines the effectiveness of photocatalytic paint, which is activated by visible light, in controlling fungal growth to enhance IAQ. Experimental results showed that when applied to grown fungi, the photocatalytic paint led to a significant reduction in the size of fungal fibers, as observed through scanning electron microscopy (SEM). Furthermore, exposure to the photocatalytic paint reduced the size of fungal hyphae by 37% after 85 h. The paint produced by adding 1 mL photocatalytic paint to 10 mL commercial paint demonstrated high efficiency in fungi removal, i.e., reducing the weight of fungi by approximately 45% within 3 h. These results highlight the potential of photocatalytic paint to significantly inhibit fungal growth, offering a promising solution for improving indoor environments.

Biosorption of dyes in wastewater using chitosan/polyethylene nanoparticle as adsorbent

Chitosan/low-density polyethylene (CHNP/LDPE) nanoparticles, sized at approximately 200 nm, were developed as effective adsorbents for removing dyes from wastewater. This study involved a systematic experimental investigation to evaluate the effects of several parameters: adsorbent dosage, contact time, temperature, pH, and initial dye concentration, all conducted in batch experiments at ambient temperature. The optimal adsorption conditions were identified; specifically, a pH of 5 was most effective for Methylene Blue (MB) dye, while a pH of 6 yielded the best results for Bromocresol Green (BG) dye. The highest removal efficiency was observed with an initial dye concentration of 50 mg/L and an adsorbent dosage of 0.05 mg/L. Equilibrium studies indicated that the adsorption process conformed to the Langmuir isotherm model for single systems. Notably, MB exhibited a higher adsorption capacity of 147 mg/g compared to BG’s capacity of 142.8 mg/g. These findings underscore the potential of CHNP/LDPE biocomposites as a novel biosorbent for dye removal in wastewater treatment applications, suggesting an efficient and environmentally friendly approach to managing dye pollutants.Graphical abstract

Enhanced Organics Removal Using 3D/GAC/O3 for N-Containing Organic Pharmaceutical Wastewater: Accounting for Improved Biodegradability and Optimization of Operating Parameters by Response Surface Methodology

Pharmaceutical industry effluents often contain high concentrations of refractory organic solvents, chemical oxygen demand (COD), and total dissolved solids (TDSs). These wastewaters, including N-containing organic solvents known for their persistence and toxicity, pose significant environmental challenges. The study evaluated the efficacy of 3D/Granular Activated Carbon (GAC)/O3 treatment compared to linear process additions when treating real pharmaceutical wastewater, and revealed a 2.73-fold enhancement in COD mineralization. The process primarily involves the direct oxidation of monoprotic organic acids found in real pharmaceutical effluents, such as acetic and formic acid, crucially influencing mineralization rates. Optimal conditions determined via the response surface methodology were 125 g/L GAC, 30 mA/cm2, and 75 mg/L O3, achieving high total organic carbon (TOC) and COD removal efficiencies of 87.19 ± 0.19% and 89.67 ± 0.32%, respectively (R2 > 0.9), during verification runs. Current density emerged as the key parameter for organic abatement, aligning with the emphasis on direct oxidation at the anode surface. This integrated approach enhances biodegradability (BOD5/COD) and reduces acute toxicity associated with persistent N-containing solvents, demonstrating promising applications in pharmaceutical wastewater treatment.

A multi-dimensional comparative study on the performance of algae removal using various flotation

Flotation is considered the most cost-effective and efficient algae-water separation technology. However, there are various flotation techniques for algae removal, such as coagulation-flotation (CF), foam flotation (FF), and positively charged bubble flotation (PF). It remains unclear which method is most suitable for removing algae from water bodies and under what specific conditions each technique is most effective. This study systematically compares CF, FF, and PF in terms of algal cell removal efficiency, concentration ratio, flotation kinetics, impact on algal cells, removal efficiency of algal organic matter (AOM) and microcystins (MC-LR), as well as economic cost analysis. CF is better suited for algae removal in water bodies, including drinking water sources, using fixed installations on shore due to its high removal efficiency, high concentration ratio, low chemical dosage, and minimal residuals. FF is more appropriate for non-drinking water sources as it can remove algae and further control algal growth; however, its residual CTAB may pose a threat to drinking water safety. PF is most suitable for in situ algae removal within water bodies, primarily because it does not require stirring or coagulation. Instead, modified bubbles can be directly introduced into the algal distribution layer, where they adhere to algal cells, facilitating algae-water separation. All three flotation methods are economically feasible for algae removal. For FF, the costs of chemicals and electricity are nearly equal, while for CF and PF, the primary cost is electricity. This study provides data to support the selection of appropriate flotation technologies for emergency removal of algal blooms in water bodies.

Homogeneous Crystallization of Nickel as Ni₃S₄ in a Fluidized Bed Reactor with Supersaturation Control

This study investigates the recovery of nickel sulfide (NiS) using fluidized bed homogeneous crystallization (FBHC), emphasizing the process from nucleation to crystallization. Sludge production in conventional chemical precipitation becomes a drawback in treating wastewater economically and efficiently. FBHC offers a promising alternative by minimizing sludge generation. The study examines various operational parameters, including hydraulic retention times (HRT), reflux ratio (R), initial nickel concentration, and static bed height (SBH), to optimize NiS recovery. Results show that FBHC achieves high total removal efficiency (TR) and crystallization ratio (CR), under the optimum condition of HRT = 15min, R = 8.3, initial nickel concentration = 147mg/L, and SBH = 35cm. The agglomeration of Ni(OH)2 was found to be crucial for the crystal growth during the surface oxidation of Ni3S4. This technological approach to wastewater treatment offers highly efficient heavy metal removal from wastewater.

Construction of electron-deficient Co on the nanoarrays enhances absorption and direct electron transfer to accelerate electrochemical nitrate reduction

Electrochemical nitrate reduction is a promising remediation strategy for nitrate-contaminated wastewater treatment, in which nitrate adsorption is a prerequisite step in the overall process. Herein, the iron-induced cobalt phosphide was grown in situ on porous nickel foam (Fe-CoP/NF) for the electrochemical nitrate reduction. Structural characterization verified doping of Fe and the uniform nanotube arrays of Fe0.03CoP/NF. Remarkably, the Fe0.03CoP/NF exhibited a high efficiency nitrate removal efficiency (99.3%) and excellent ammonia selectivity (100% selectivity and 0.485mg·h-1cm-2 NH3 yield rate). Both experimental and theoretical results reveal that Fe doping alters the local charge distribution of the Co active centers to form electron-deficient Co. The Co electron-deficient regions were constructed due to the difference in electronegativity between Co and Fe. Furthermore, the formation of electron-deficient centers facilitates the reduction of charge transfer resistance. In particular, Fe0.03CoP/NF maintained an excellent conversion efficiency of nitrate to N2 (99.8%) with 60mM Cl−, and the selectivity of N2 is maintained above 99.1% during long-term operation. This system possesses a low electrical consumption of 1.79 kWh·molN-1. This study designed an enhanced electrocatalyst through enhanced nitrate absorption and direct electron transfer strategies, thus providing a promising and low-power consumption approach for addressing nitrate pollution.

Highly competent elimination of diverse toxic heavy metal oxo-anions by novel 2D guanidinium-based ionic covalent organic framework

Different types of heavy metal oxo-anions often occur together in the environment. It is a great challenge to remove them simultaneously as they behave differently at different pH values of the water source. In this work, 2D guanidinium-based ionic covalent organic framework (iCOF) exhibits excellent reducibility and stability for the removal of oxo-anions and showed very high removal efficiency of single and mixed heavy metal oxo-anions in the working pH range. The chemical nature of adsorption was confirmed by kinetic and isothermal mathematical modelling. The iCOF was tested in four types of wastewater, and the results show that 1 kg iCOF can decontaminate >2000 litres of ⁓10 mg L-1 Cr(VI), V(V) and Se(IV), at a cost of $579 to the EPA discharge limit. The comprehensive study of this work has broader applications that can be used for the treatment of toxic heavy metal contaminants from wastewater.

Fe3O4 nanoparticles decorated on N-doped graphene oxide nanosheets for elimination of heavy metals from industrial wastewater and desulfurization

Finding an effective and excellent pertinent single catalyst material for multipurpose application for the purification of hydrocarbons in fuels (desulfurization), and for efficient removal of heavy metals from industrial effluent is greatly endowed. In the present work, a hybrid nanocomposite of ultrafine magnetite (Fe3O4) nanoparticle embedded on the surface of in-situ nitrogen doped layered GO (NGO) sheets were fabricated by sol-gel method and treatment with microwave irradiation technique is reported for the first time. The results show a high removal efficiency of 97 % for multiple heavy metals (Pb2+, Cd2+, Cu2+, Cr+2, Mn+2etc.) in industrial effluent and as well as in synthetic water with a very good retention performance of 99 %. The composites were tested against the elimination of sulfur from thiophene is 1.495 mmol g−1 is reported high is due to coupling and coordination of nitrogen with FeO and C. Recycling studies showed that the developed composites had excellent recyclability, with <82 % removal at the 5th cycle; its feasibility was evaluated using industrial effluent water and in synthetic water. Surface phenomena studies presented here revealed that the adsorptive removal processes of heavy metals involved π electron donor-acceptor interactions, ion exchange, and electrostatic interactions, along with surface complexation that showed an excellent synergism. A high stability, and retention performance is better than the pure Fe3O4 and NGO sheets. We hope that this study will motivate and give further scope for scientists working on magnetite-based graphene nanocomposites.

Synthesis of MOF@COF composites and study on dye adsorption properties

MOF@COF hybrid materials not only have high stability and adjustable function, but also have the characteristics of MOFs and COFs materials, which make them have important application value in the field of adsorption. This article employs 1,3,5-benzene tricarbonyl chloride and p-Phenylenediamine as covalent organic framework monomers. Through the in-situ growth of covalent organic frameworks (COF) on the surface of NH2-MIL-88(Fe) material, a novel, stable, and porous COF-on-MOF hybrid material (NH2-MIL-88(Fe)/COF) was synthesized. The structure, morphology, and performance of the hybrid material were thoroughly examined using characterization techniques, including Fourier-transform infrared spectroscopy (FT-IR), powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), and thermal gravimetric analysis (TGA). Subsequently, We explored the MOF@COF hybrid material as an effective adsorbent for removing organic dyes, namely methylene blue (MB), methyl orange (MO), and crystal violet (CV). The influence of various adsorption parameters, such as adsorption time, initial dye concentration, and different pH values, on dye adsorption performance was systematically investigated. Experimental results revealed that at pH = 7, NH2-MIL-88(Fe)/COF demonstrates maximum adsorption capacities of 114 mg·g−1, 106 mg·g−1, and 102 mg·g−1 for methylene blue, methyl orange, and crystal violet, respectively. The adsorption process follows pseudo-second-order kinetics and Langmuir isotherm models. Lastly, NH2-MIL-88(Fe)/COF maintains high removal efficiency for the three dyes even after five repeated uses, establishing it as a stable and efficient adsorbent. The research findings suggest that MOF@COF hybrid materials hold promising applications in the treatment of dye-containing wastewater.

Efficient nitrogen removal and stable operation of a dynamic membrane bioreactor (DMBR) for landfill leachate treatment

This study proposed a novel anoxic/4-stage aerobic/self-forming dynamic membrane bioreactor (DMBR) process for treating landfill leachate with low carbon-to-nitrogen ratio (COD/N). When the influent COD and NH4+-N were 3689 ± 425 and 1042 ± 96 mg/L, high removal efficiencies of 87 % for COD and 79 % for TN can be achieved. The mature dynamic membrane (DM) was rapidly established within 1 h, allowing one operational cycle to last over 20 days with the permeate turbidity below 5 NTU. The primary cause of biofouling was identified as the accumulation of small particles, proteins, polysaccharides, and inorganic components such as Ca2+ and Mg2+ in the DM layer. In addition, significant up-regulation of genes associated with quorum sensing signaling molecules (such as pac, trpE, dgcB), extracellular polymeric substances secretion (exoP, exoQ, algA), and biofilm formation (lasA) were observed in the DM layer, while some genus, like Thauera, Anaerolinea and Caldilinea were highly enriched in DM layer. These findings indicate that DMBR offers cost-effective and technically advantageous operations, making it a promising candidate for the treatment of high-strength landfill leachate.

Modular hydrogel selectively adsorbs phosphates and hexavalent chromium while enabling phosphate recovery

Electroplating wastewater containing high concentrations of phosphates and hexavalent chromium Cr(VI) poses serious environmental pollution. Moreover, phosphorus, as a non-renewable resource, necessitates its recovery to meet sustainable development goals. To address this issue, this study used sodium alginate as the scaffold module, synthesized lanthanum carbonate in situ within a chitosan module to serve as the phosphate adsorption module, and employed polyethyleneimine (PEI) modules to enhance the adsorption capacity for Cr(VI), successfully fabricating a modular hydrogel (LC-CSP). LC-CSP exhibits a complex porous structure and surface morphology, forming an ultra-low-density fiber network with good strength and elasticity, ensuring uniform distribution and exposure of active sites. Under optimal conditions for single-component adsorption, LC-CSP achieved adsorption capacities of 232.02 mg/g for phosphates and 474.61 mg/g for Cr(VI). Additionally, LC-CSP demonstrated excellent reusability, retaining over 83 % of its performance after five cycles. In simulated electroplating wastewater experiments with various interfering substances, LC-CSP maintained high removal efficiencies (>90.72 %) for phosphates and Cr(VI). Post-experiment, enriched water after phosphate desorption was further treated to recover phosphorus resources in complex water environments. Multiple characterization techniques elucidated the adsorption mechanisms of LC-CSP: phosphate adsorption primarily involved ligand exchange, electrostatic interactions, and hydrogen bonding, while Cr(VI) adsorption included electrostatic interactions, hydrogen bonding, and reduction reactions. Finally, fixed-bed simulated wastewater adsorption experiments validated the technical potential of LC-CSP for practical electroplating wastewater management.

Experimental and numerical study of microbubble-enhanced separation of aged microplastics in a slurry flow

Microplastics (MPs) are widespread in aquatic environments, causing ecological issues worldwide. Microbubble (MB) technology has been extensively used in various industries due to its high efficiency, low cost, and sustainability, particularly in separation processes. However, its application in slurry flows containing solid particles, such as slurries with sands, remains underexplored. This study develops microbubble (MB)-enhanced separation of microplastics (MPs) in slurry flow containing 10 % sands in a pipeline. Key experimental parameters, including particle density, size and surface wettability of MPs, and bubble volume fraction, were systematically examined at the flow velocity of 2 m/s to compare the removal efficiency of MPs. As the volume fraction of bubbles in the flow varied from 0 to 0.5 %, the removal efficiency of aged polystyrene (PS) MPs was increased by 95 %. Computational fluid dynamics (CFD) simulations were performed to reveal the influence of MBs on the distribution of MPs in the slurry flow. The validated models predict that microbubbles promote accumulation of MPs near the pipe top by 7 times. Such localized accumulation of MPs in the slurry may be attributed to high removal efficiency by MBs. This work presents an innovative and efficient method for MB generated in-situ for markedly improved separation efficiency of MPs from slurry flows.

Catalytic chitosan/MXene/GO nanocomposite membrane for removing dye and heavy metals

This work reported the preparation of a catalytic nanocomposite nanofiltration (NF) membrane and its performance in removing dye and heavy metals without requiring UV irradiation. Two-dimensional (2D) materials MXene and graphene oxide (GO) were employed in developing chitosan-based catalytic nanocomposite membranes for the removal of dye molecules and heavy metals from textile industry wastewater. The incorporated MXene catalytically decomposed the hydrogen peroxide (H2O2) and generating reactive oxygen species (ROS), which oxidize methylene blue (MB) and reduce cobalt (Co2+) and copper (Cu2+) ions. The electron paramagnetic resonance spectroscopy and fluorescence emission spectroscopy confirmed the generation of superoxide radicals (•O2−). The fabricated chitosan/MXene/GO (CMG) membrane in this research exhibited high removal efficiencies of 96 %, 78 % and 76 % for dye, cobalt ions and copper ions, which were 4, 3.9 and 4 times higher than that of neat membrane, respectively. Similar results of 95 % were also observed in total organic matter (TOC) removal for both concentrations of dye. The CMG membrane also showed superior organic fouling resistance. The findings provided a new insight for non-UV dependent catalytic nanocomposite NF to efficiently remove hazardous contaminants such as dye and heavy metals from industrial effluent.