Filtration Cycle Research Articles

Effect of Operational Parameters and Iron Ore Tailings Properties on Filter Cake Porosity

Objective: By evaluating operational filtration conditions, chemical, mineralogical, and particle size properties of the tailings, the study aimed to identify critical variables affecting porosity and provide predictive models for optimizing dewatering operations. Theoretical Framework: This research builds upon existing theories of solid-liquid separation and dewatering processes in mineral processing. Key references include classical works on filtration dynamics, particle size distribution, and cake porosity characterization. The study addresses gaps in literature regarding the relationship between tailings composition and filtration results. Method: The Leaf Test method was employed on 33 fresh slurry samples from the Brucutu plant to simulate industrial filtration conditions. Filtration cycle parameters such as cake formation and drying times were standardized. Porosity was calculated using Grace's equation and correlated with characterization data, including mineralogical composition, true density, and particle size. Statistical methods such as clustering, regression, and Random Forest modeling identified key predictors of porosity. Results and Discussion: The results indicated that porosity correlates strongly with silica content and certain mineralogical attributes, such as the presence of martitic hematite and quartz. Cluster analysis revealed two sample groups with distinct filtration characteristics. While operational parameters showed limited impact on porosity, the statistical models highlighted the significance of ore composition. Research Implications: This research provides a foundation for optimizing iron ore tailings filtration by identifying the key variables influencing porosity. The findings support more efficient dewatering techniques, contributing to sustainable tailings management. Further, the development of predictive models aids industrial operations in minimizing risks associated with tailings disposal. Originality/Value: This study is among the first to integrate statistical modeling and mineralogical characterization in exploring filter cake porosity. The results offer novel insights into the optimization of solid-liquid separation processes in the mining industry.

Mechanical and antimicrobial properties of green and photoactive AgTiO2/poly(3hydroxybutyrate) (PHB) electrospun membranes

AbstractThe rise of antibiotic‐resistant microbes and concerns over non‐biodegradable waste highlight the need for innovative materials with integrated functionalities that address these critical issues. In this study, we synthesized poly(3hydroxybutyrate) (PHB) electrospun nanofibers blended with gelatin (Ge) and loaded with photoactive AgTiO2 nanoparticles with improved mechanical and biological properties. Biological tests revealed excellent antibacterial activity of the prepared membrane, with efficiency exceeding 99% against Escherichia coli and 95% against Staphylococcus epidermidis after 90 and 60 min of exposure to low‐power commercial LED lights, respectively. Filtration studies using a dead‐end stainless‐steel cell reveal that both bacteria are eliminated (>99% after one filtration cycle). Results of the viability test showed that blending PHB with Ge improves the membrane's anti‐biofouling properties. The membranes were also characterized using SEM and EDX mapping techniques for morphological and elemental analysis, DSC and TGA to evaluate thermal properties and crystallinity, and FTIR to confirm chemical structure. Moreover, the electrospun membranes exhibited enhanced mechanical properties with the addition of Ge. PHB/Ge/3 wt% AgTiO2 sample showed 2.2 times better tensile strength and 1.89 times improved Young's modulus compared to PHB membranes. Finally, the breakdown of PHB/Ge/AgTiO2 membranes occurred progressively over only 8 weeks, showing the membranes' green and sustainable nature.Highlights Antibacterial efficacy of 99% against E. coli and 95% against S. epidermidis. Microfiltration efficiency >99% achieved in one filtration cycle. Mechanical strength is enhanced by 2.2 times with the addition of gelatin. Effective anti‐biofouling is confirmed by CLSM and SEM tests. Membranes degraded within 8 weeks in natural soil.

Glycopolymer-Mediated Selective Separation of Middle Rare Earth Elements.

The selective separation of rare earth elements (REEs), particularly middle REEs (MREEs) with intermediate ionic radii, poses significant challenges for current methods. In this study, we introduce a novel approach that leverages negatively charged glycopolymers for size-specific separation of MREEs. By varying glycopolymer properties such as degree of polymerization (DP) and charge density, we achieved a distinct U-shaped selectivity profile, with a pronounced preference for Samarium (Sm) and Europium (Eu) over other REEs like Cerium (Ce), Gadolinium (Gd), and Holmium (Ho). Enrichment experiments demonstrated the practical potential of this methodology, achieving over 10% selectivity for Sm in Ce/Sm and Ho/Sm mixtures (10:1 ratios). Further, a separation experiment with a 1:1 Ce/Sm mixture yielded 15% enrichment after five filtration cycles with minimal glycopolymer, underscoring the approach's effectiveness. This work highlights the promise of glycopolymer-based strategies for targeted MREE separation, offering an efficient and tunable pathway for refining separation processes in REE applications.

Glycopolymer‐Mediated Selective Separation of Middle Rare Earth Elements

The selective separation of rare earth elements (REEs), particularly middle REEs (MREEs) with intermediate ionic radii, poses significant challenges for current methods. In this study, we introduce a novel approach that leverages negatively charged glycopolymers for size‐specific separation of MREEs. By varying glycopolymer properties such as degree of polymerization (DP) and charge density, we achieved a distinct U‐shaped selectivity profile, with a pronounced preference for Samarium (Sm) and Europium (Eu) over other REEs like Cerium (Ce), Gadolinium (Gd), and Holmium (Ho). Enrichment experiments demonstrated the practical potential of this methodology, achieving over 10% selectivity for Sm in Ce/Sm and Ho/Sm mixtures (10:1 ratios). Further, a separation experiment with a 1:1 Ce/Sm mixture yielded 15% enrichment after five filtration cycles with minimal glycopolymer, underscoring the approach's effectiveness. This work highlights the promise of glycopolymer‐based strategies for targeted MREE separation, offering an efficient and tunable pathway for refining separation processes in REE applications.

Weakly-negatively-charged loose nanofiltration membranes tailored by polyethyleneimine for dye/salt separation

Loose nanofiltration membranes with a weakly negatively charged surface were made from interfacial polymerization between natural hydrophilic polymer carboxylated chitosan (C-CS) and trimesoyl chloride (TMC) firstly and further depositing branched polyethyleneimine (PEI) on top of the surface to tailor the membrane structures and surface charge properties. This kind of membrane was exploited for dye/salt separation in textile wastewater treatment. The effects of contents and molecular weights of PEI on the morphologies, surface charge, hydrophilicity, pore size, and dye/salt separation performance of the membrane were comprehensively investigated. We found that the top layer of PEI with a moderate molecular weight is suitable to form a loose structure for dye/salt separation. The optimized membrane has a comparable high water permeability (44.4 L/m2.h.bar), a low salt rejections (2.6 % for Na2SO4, 7.7 % for NaCl, and 6.8 % for MgCl2), a relatively high dye rejection (96.9 % for Congo Red, 85.4 % for Methyl Blue, 51.1 % for Bromophenol Blue, and 48.3 % for Reactive Black 5), and an extremely high CR/Na2SO4 fractionation ratio (37.27). Moreover, the resultant membrane shows excellent anti-fouling performance after 5 cycles (50 h) of filtration. It maintains a high Congo Red rejection during a 10-day long-term run. This study shows an easy way to fabricate and adjust the properties of loose nanofiltration membranes that work well for dye/salt separation using common and low-cost polymers. It shows promising potential in the application of textile wastewater treatment and resource recovery.

TiO2-embedded dual-layer mullite hollow fiber membranes for efficient removal of Persistent organic pollutants from wastewater

Persistent organic pollutants (POPs) are toxic pollutants that harm the environment and ecosystems. This study presents a novel approach to develop a dual-layer hollow fiber ceramic membrane for phenolic compound removal. A co-extrusion-based phase inversion process and co-sintering techniques were employed to fabricate the membrane, and the effects of TiO2 loadings on the outer layer were investigated. Characterization techniques, including FTIR, SEM, EDX, and zeta potential analysis, were used to analyze the mullite and TiO2 powders and membranes. The membrane’s performance was evaluated through rejection tests of POPs at various concentrations (10, 500, and 1000 ppm) and fouling assessments were conducted. The results showed that the M−MT0.6 membrane, with a mean pore size of 0.0245 μm, effectively rejected benzoic acid (81.45 %), gallic acid (91.45 %), and hydroquinone (74.49 %) from wastewater, achieving the highest permeate flux (1320.50 L/m2·h) for gallic acid at 10 ppm. Additionally, M−MT0.6 exhibited minimal fouling over a 1-h filtration cycle, with the lowest fouling rate (35.1 %) recorded at 1000 ppm for BA, attributed to effective backwashing. However, higher fouling rates were observed at 10 ppm for BA (90.10 %) and HQ (83.50 %). Overall, this study demonstrates the potential of the novel membrane for effective removal of POPs from industrialwastewater.

Low-energy advanced wastewater treatment using submerged nanofiltration

The use of submerged nanofiltration (NF) membranes in wastewater treatment is an emerging process that produces high-quality recycled water with low energy consumption. This study aimed to identify the potential of coupling anaerobic digestion with this low-energy advanced wastewater treatment using submerged NF membranes. The direct NF of primary wastewater effluent using four types of commercial NF membranes resulted in progressive membrane fouling over 4 d. However, almost all the foulants contributing to hydraulic loss were removed by one-swipe sponge cleaning. This indicated that the major foulants were generally deposited on the membrane surface during direct NF. The membrane fouling speed varied during the long-term test depending on the feed wastewater quality. Although the transmembrane pressure increased by up to 50 kPa in every filtration cycle (4–7 d), sponge cleaning removed all the membrane foulants, resulting in >30 d of operation without chemical cleaning. The NF concentrates (four times concentrated wastewater) were then used for biogas production in an anaerobic digester. The volume of biogas formed from the NF concentrates sufficiently compensated for the energy consumption of direct NF. This study realized a low-energy advanced wastewater treatment utilizing NF concentrates that can also be used for biogas formation.

Mixed matrix membranes by post-modified UiO-66-NH2 for efficient treatment of dyeing wastewater

The preparation of modified membranes utilizing the UiO-66 framework for wastewater filtration is regarded as one of the most promising approaches to wastewater treatment, owing to its high efficiency and cost-effectiveness. In this study, a post-modified MOF, UiO-66-RSA, was synthesized via the condensation reaction of UiO-66-NH2 and 2,4-dihydroxybenzaldehyde. PVDF mixed matrix membranes (MMMs) were fabricated for the first time by mixing UiO-66-RSA into PVDF using the non-solvent induced phase separation (NIPS) method. Compared to pure PVDF membranes, the newly developed membrane, M4, demonstrated enhanced compatibility and superior mechanical strength. In dyeing wastewater treatment applications, M4 showed excellent separation efficiency for dye and heavy metal mixed wastewater, achieving rejection rates exceeding 90 %. Additionally, it maintained a high flux recovery rate (FRR > 90 %) and rejection rate (Rejection > 90 %) after six filtration cycles of dye-containing wastewater, indicating strong recyclability. These findings suggest that MMMs embedded with UiO-66-RSA hold significant promise for dyeing wastewater treatment.

Multienzyme Immobilization on PVDF Membrane via One-Step Mussel-Inspired Method: Enhancing Fouling Resistance and Self-Cleaning Efficiency.

Immobilizing different enzymes on membranes can result in biocatalytic active membranes with a self-cleaning capacity toward a complex mixture of foulants. The membrane modification can reduce fouling and enhance filtration performance. Protease, lipase, and amylase were immobilized on poly(vinylidene fluoride) (PVDF) microfiltration membranes using a polydopamine coating in a one-step method. The concentrations of polydopamine precursor and enzymes were optimized during the immobilization. The higher hydrolytic activities were obtained using 0.2 mg/mL of dopamine hydrochloride and 4 mg/mL of enzymes: 0.90 mgstarch/min·cm2 for amylase, 10.16 nmoltyrosine/min·cm2 for protease, and 20.48 µmolp-nitrophenol/min·cm2 for lipase. Filtration tests using a protein, lipid, and carbohydrate mixture showed that the modified membrane retained 41%, 29%, and 28% of its initial water permeance (1808 ± 39 L/m2·h·bar) after three consecutive filtration cycles, respectively. In contrast, the pristine membrane (initial water permeance of 2016 ± 40 L/m2·h·bar) retained only 23%, 12%, and 8%. Filtrations of milk powder solution were also performed to simulate dairy industry wastewater: the modified membrane maintained 28%, 26%, and 26% of its initial water permeance after three consecutive filtration cycles, respectively, and the pristine membrane retained 34%, 21%, and 7%. The modified membrane showed increased fouling resistance against a mixture of foulants and presented a similar water permeance after three cycles of simulated dairy wastewater filtration. Membrane fouling is reduced by the immobilized enzymes through two mechanisms: increased membrane hydrophilicity (evidenced by the reduced water contact angle after modification) and the enzymatic hydrolysis of foulants as they accumulate on the membrane surface.

Study of Graphene Oxide/Polymer Composite Membranes in Air Filtration of PM2.5

pollution, particularly the issue of fine particulate matter (PM2.5), which has emerged as a significant environmental and public health concern globally. It is particularly important to develop efficient, economical and sustainable air filtration materials to reduce the concentration of PM2.5. In this study, we investigated the potential application of some polymers such as polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN) and polyaniline (PANI) composites with graphene oxide (GO) for efficient PM2.5 filtration. These composites were found to have excellent filtration performance, thermal stability. PVDF/ GO/PI nanofiber membranes maintained stable performance under repetitive filtration cycles and high temperature conditions. PAN/GO/PI nanofiber membranes exhibited good mechanical properties and stable cycling performance.PANI/GO composites took advantage of the unique properties of the conductive polymers, and in TGA experiments, they showed minimal mass loss. Their durability and efficiency remain high even after multiple wash cycles, highlighting their potential for practical applications.

Performance and analysis of kappa-carrageenan hydrogel for PFOA-contaminated soil remediation wastewater treatment

Perfluorooctanoic acid is an emerging pollutant with exceptional resistance to degradation and detrimental environmental and health impacts. Conventional physical and chemical processes for Perfluorooctanoic acid are either expensive or inefficient. This study developed an environmentally sustainable and cost-effective gravity-driven kappa-carrageenan (kC)-based hydrogel for perfluorooctanoic acid (PFOA) removal from synthetic and actual wastewater. Two kC filters were prepared by mixing activated carbon (AC) or vanillin (V) with the kC hydrogel to optimize the hydrogel selectivity and water permeability. Experimental work revealed that the PFOA rejection and water permeability increased with the AC and V concentrations in the kC hydrogel. Experiments also evaluated the impact of feed pH, PFOA concentration, hydrogel composition, and hydrogel thickness on its performance. Due to pore size shrinkage, the AC-kC and V-kC hydrogels achieved the highest PFOA rejection at pH 4, whereas the water flux decreased. Increasing the PFOA concentration reduced water flux and increased PFOA rejection. For 2 cm hydrogel thickness, the water flux of 3%kC-0.3%AC and 3%kC-3%V hydrogels was 25.6 LMH and 21.5 LMH, and the corresponding PFOA rejection was 86.9% for 3%kC-0.3%AC and 85.7% for 3%kC-3%V. Finally, the kC-0.3%AC hydrogel removed 81.1% of PFOA from wastewater of 179 mg/L initial concentration compared to 79.3% for the kC-3%V hydrogel. After three filtration cycles, the water flux decline of 3%kC-0.3%AC was less than 10%. The gravity dead-end kC hydrogel provides sustainable PFOA wastewater treatment with biodegradable and natural materials.

Implementation of Cellulose-Based Filtration Aids in Industrial Sunflower Oil Dewaxing (Winterization): Process Monitoring, Prediction, and Optimization.

In the production of refined sunflower oil, waxes are removed during the winterization stage, and wax crystals are separated through filtration assisted by filtration aids. Commonly used filtration aids in oil refining include perlite and diatomaceous earth. After winterization, a significant amount of filter cake remains as a by-product and is treated as waste. Today, natural cellulose fibers are being promoted as filtration aids. Their advantages are numerous, both in the production process and from an environmental perspective. However, their only disadvantage is their higher cost. Therefore, in this study, 57 filtration cycles during the industrial sunflower oil winterization step using cellulose-based filtration aids were monitored. Different process parameters, including the pressure differential on the filter, the flow rate of filtered oil, constant pressure period, the quantity of filtered oil, filtration time, the quantity of pre-coating and dosing filtration aids, the volume of filtered oil, the concentration of dosing filtration aid, as well as the mass of separated waxes, were observed. Additionally, artificial neural networks were applied to predict process parameters, optimize the process, and, above all, determine the dosage of filtration aids, which will make the process more economical. The optimal filtration process is performed at a pressure differential of 3.3 bar, lasting a total of 39 h, with 32 h at constant pressure, resulting in 322,503 kg of filtered oil and 90.41 kg of waxes. The optimal quantity of cellulose-based filtration aids employed for pre-coat was 80 kg, and for dosing, 375 kg, with an optimal concentration of 0.12% w/w.

Fabrication and characterization of poly(methyl vinyl ether maleic anhydride) blended poly(lactic acid) ultrafiltration membrane with upgraded antifouling and separation performance

In this present study, a novel environment-friendly bio-polymeric hybrid ultrafiltration membrane was fabricated by incorporating poly(methyl vinyl ether maleic anhydride) (PMVEAMA) into the poly(lactic acid) (PLA) polymer matrix. The integration of PMVEAMA into PLA significantly altered the membrane's structural morphology, functional characteristics, and filtration performance. As a result, key functional parameters like membrane porosity and water content were increased, which exhibiting the improved hydrophilicity. Furthermore, the molecular weight cut-off of the PLA/PMVEAMA membrane reached up to a maximum of 66.5 KDa with an average pore size of 9.14 nm, subsequently improving the flux of the membrane up to 2.8 times than PLA membrane. The functional capacity of the synthesized membrane was further assessed by testing its ability to filter toxic chlorophenolic compounds. Rejection studies reveal that the PLA/PMVEAMA membrane achieved a rejection efficiency of 44.64 % pentachlorophenol (PCP) and 51.85 % 2,4-dichlorophenol (DCP). Moreover, fouling studies revealed enhanced PCP and DCP flux recovery ratios of 50.94 % and 51.40 %, respectively, with a significant reduction in the flux decline rate. Additionally, the synthesized PLA/PMVEAMA membranes improved stability and regenerative properties up to 12 filtration cycles and antifouling properties highlight its potential to filter chlorophenolic compounds from wastewater.

Enhancing demulsification efficiency and sustaining constant separation flux in oil/water emulsions via Janus membrane inspired by spider silk

Conventional special wettable membranes for the separation of the surfactant-stabilized oil/water emulsions primarily rely on the “size-sieving” mechanism, which enhances efficiency by reducing the pore size, leading to a trade-off between separation flux and efficiency. Inspired by spider silk, we developed a novel Janus membrane (JPSPP) capable of high demulsification capacity and constant separation flux. This membrane combines a superhydrophobic PS@PDMS membrane (PPM) with spindle-knotted structures on a negatively charged superhydrophilic PAN@SAS membrane (PSM) through electrospinning. The synergy of electrostatic force generated by charged surfaces, the Laplace pressure created by spindle-knotted geometry, and the wettability gradient resulting from asymmetric wettability enhance the demulsification capacity. The high and constant separation flux was achieved as Laplace pressure drives rapid coalescence of demulsified oil droplets towards the top of the spindle-knotted structures, facilitating oil detachment and efficient water permeation downward. As a result, the JPSPP membrane achieved a separation efficiency exceeding 99.9 %, with a constant separation flux of up to 1952.27 L m−2 h−1, representing a 3–4 folds improvement compared to the pure PAN membranes (PM). The separation performance of the JPSPP still maintains excellent separation performance with efficiency above 98.3 % and a slight attenuation in flux after twenty filtration cycles. The research proposes groundbreaking solutions that significantly enhance the demulsification efficiency and maintain a constant separation flux for oil/water emulsions, with the potential to profoundly impact multiple industries including food processing, energy production, and the petroleum industry, etc.

An “all-in-one” and confined self-enhancing Fenton-like membrane reactor for multiple antibiotic treatment in aquatic environment at natural pH

Conventional Fenton oxidation technique utilized for the treatment of antibiotics is plagued by issues such as extra H2O2 requirement and harsh reaction conditions. In this work, an “all-in-one” membrane reactor with H2O2 self-supply and self-catalysis at natural pH conditions for multiplex antibiotic residues degradation was developed by loading bifunctional composite Pt/CuO2 Janus nanoparticles (Pt/CuO2 JNPs) on the surface of the PVDF membrane. Specifically, the Fenton reagents H2O2, which was generated from the decomposition of the functional material CuO2 NPs in a near natural pH condition without extra addition, was synergistic activated by nano-enzyme Pt NPs and Cu2+. This, in turn, greatly improves the practicability of the reactor. Notably, the large number of nanopores present on the surface of the reactor endows it with a confined self-enhancing effect, which could greatly improve its catalytic degradation efficiency of antibiotics. The developed membrane reactor is capable of degradation 97.6 % of chloramphenicol (CAP) residues after several cycles of filtration. The apparent rate constant of the developed membrane reactor for CAP is approximately folded for the bulk reaction system. What’s more, the developed membrane reactor features favorable usability and preservability and superior universality for common antibiotics.

Rejuvenated end-of-life reverse osmosis membranes for landfill leachate treatment and reuse water reclamation

Landfills remain a prevalent method for municipal solid waste disposal, yet concerns persist regarding leachate generation and its environmental impact. This research paper investigates the reuse of end-of-life reverse osmosis membranes for treating landfill leachate (LL) after their rejuvenation. The rejuvenation process involved a specific chemical cleaning procedure that allows for permeability recovery without compromising the membrane rejection capacity when compared to o pristine reverse osmosis. It was also explored the hypothesis how previous membrane use affects the rejuvenation process by considering end-of-life membranes used for desalination of brackish water and treated water. While both could be effectively rejuvenated, those used for brackish desalination were more susceptible to irreversible fouling. In such cases, recycling the membrane and converting it to porous ultrafiltration or microfiltration membranes is recommended. For membranes previously used for treated water desalination, it was observed high efficiency in LL treatment across multiple filtration cycles. The average flux for these membranes corresponded to 6.9 ± 0.4 L/m2h (operating pressure: 10 bar), and the rejection were greater than 89.4 % for chemical oxygen demand and 98.6 % for color. In complement, it was investigated the contribution of pretreatment with ultrafiltration membranes. Ultrafiltration was effective in preventing membrane fouling and improving the physicochemical quality of reclaimed water from landfill leachate. Overall, this research provides valuable insights into the potential reuse of end-of-life reverse osmosis membranes from treated water desalination plant for LL treatment, contributing to sustainable waste management and wastewater treatment solutions.

Polyvinylidene fluoride-based loose nanofiltration membrane with graphene oxide intercalation for efficient small organic molecules desalination

Graphene oxide (GO) loose nanofiltration (LNF) membranes show immense potential for the desalination of small organic molecules. However, it remains a significant challenge to compare the performance of GO LNF membranes prepared via different doping methods and study the mechanisms that influence the separation abilities of the membranes. In this study, LNF membranes prepared via three GO doping methods were examined for flux, retention rate, and the separation performance of small organic molecules and inorganic salts. The membranes coated with dopamine (DA) and GO, and subsequently formed polydopamine (PDA)–GO intercalation, showed the best results. A novel LNF membrane material (PVDF/PDA–GO–TFN; PVDF: polyvinylidene fluoride, TFN: thin-film nanocomposite) was developed to enhance the separation performance of small organic molecules and inorganic salts while improving membrane surface stabilization and anti-fouling performance and reducing the “trade-off” effect. The optimal conditions for PDA–GO intercalation and the best combination for interfacial polymerization (IP) were also determined. The intercalation structure was identified via scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy, atomic force microscopy, and Fourier-transform infrared spectroscopy. Furthermore, the separation mechanism of the membrane was determined to be based on the Donnan and steric hindrance effects, according to the correlation analysis of the membrane surface electrical properties (zeta potential), hydrophilicity (contact angle), and pore properties. The PVDF/PDA–GO–TFN LNF membrane displayed a maximum water permeance of 10.45 L/(m2·h·bar), with an 88 % rejection of PEG2000 and a 6.83 % rejection of Na2SO4. Moreover, the membrane exhibited excellent anti-fouling performance and long-term stability, with a mean flux recovery rate of 99.06 % after four cycles of filtration and backwashing tests using small organic molecules and inorganic salt solutions. The inorganic salt retention rate was analyzed using SPSS software, and the results indicated excellent membrane stability. In summary, the preparation of PVDF/PDA–GO–TFN membrane materials provides a novel approach for fabricating LNF membranes that can effectively separate small organic molecules and inorganic salts.

Fabrication of Sustainable Sodium Alginate/Polyethyleneimine/Polyvinyl Alcohol Multilayer Composite Electrospun Nanofiber Membrane for Efficient Cu2+ Removal

In pursuit of sustainable solutions for water pollution mitigation, we have successfully employed electrospinning technology to fabricate a multilayered sodium alginate (SA)/polyethyleneimine (PEI)/polyvinyl alcohol (PVA) nanocomposite fiber membrane, with a focus on enhancing its adsorption capacity for Cu2+ ions in wastewater. Our research underscores the potential of this novel membrane, characterized by its small diameter, high uniformity, and expansive surface area, in effectively filtering heavy metal ions. By optimizing critical electrospinning parameters such as a voltage of 19.5 KV, a collector distance of 8 cm, a specific mass ratio of SA:PEI: PVA (1:2:6), and an injection rate of 8 μL/min, we achieved a nanofiber membrane with an average diameter of 112.5 nm, exhibiting exceptional morphological characteristics and high efficiency. Notably, the membrane exhibited an adsorption capacity of over 85% for Cu2+ during initial testing, maintaining over 80% efficiency throughout four consecutive filtration cycles. This work not only advances the field of nanocomposite membranes for water purification but also contributes significantly to the broader goal of achieving environmental sustainability by mitigating the impact of heavy metal contamination in water bodies.

A photocatalyst coupled amphiphobic membrane with enhanced antifouling and self-regenerating properties for oily aerosol filtration

Oily aerosols as the most adhesive particles in the air can cause irreversible fouling of filters. Amphiphobic surface of filters can to some extent reduce membrane fouling, but complex oil fouling will still adhere to the membrane surface, leading to a decrease in membrane separation performance over long-term use. Herein, a silicon carbide (SiC) membrane with amphiphobic properties and catalytic functions was developed to collaboratively combat pollution. Low surface free energy 1H,1H,2H,2H perfluorooctyltrichlorosilane (FOTS) monomer and TiO2 nanoparticles were individually applied to the SiC membrane. PDMS was utilized to protect the monomer from degradation by the catalyst. The membrane exhibits good anti-adhesion and photocatalysis performance for oily aerosols. The membrane exhibits excellent oily aerosol filtration efficiency (98.6 %) with a comparative low filtration resistance of 6.4 kPa, as well as a high capacity for regeneration. Under UV light, the membrane can degrade oily fouling to recover its amphiphobic property. After 5 cycles of filtration, it still maintains good repeatability for oily matter separation and degradation. This study offers a practical approach to designing a membrane that enables long-term and efficient cleaning of oily aerosols.

Exploring the mechanism of membrane fouling alleviation with furanone and its derivatives addition as quorum sensing inhibitors

Membrane fouling is still the primary bottleneck issue for the widespread application of anaerobic membrane bioreactor (AnMBR) and quorum quenching (QQ) strategy is one of the feasible approaches for its fouling alleviation. In this study, 2(5H)-furanone was applied as an efficient, cost-effective and non-toxic QSI in a laboratory-scale AnMBR, achieving not only a doubled membrane filtration cycle length but also ensuring relatively stable treatment performance and enhanced methane production. The retarded membrane fouling could result from reduced soluble microbial product (SMP) and extracellular polymer substance (EPS) concentration, decreased by 13.6 % and 26.8 % compared with that in conventional AnMBR. Meanwhile, the biocake morphology also suggest reduced biofilm thickness and less organic deposition on the QQ-AnMBR. The microbial diversity analyses indicated that 2(5H)-furanone addition can accumulate the fermentative and acetogenic bacteria (Propioniciclava, Longilinea and norank_f__Anaerolineaceae in both sludge mix suspensions and biocake) and methanogens (Methanosaeta in bulk sludge, Methanosaeta and Methanobacterium in the biocakes), improving the anaerobic process in AnMBR. Moreover, the relative abundance of norank_f__norank_o__SJA-15, a typical filamentous bacterium and fouling-related microbe, significantly reduced after 2(5H)-furanone addition in the bulk sludge of QQ-AnMBR. Additionally, this study elucidated the membrane fouling control mechanism by 2(5H)-furanone addition through metagenomic and molecular docking analyses. Results indicate that 2(5H)-furanone may control membrane fouling mainly through quorum sensing processes inhibition by (i) competition of 2(5H)-furanone and acyl-homoserine lactones (AHLs) for binding sites on QS receptor proteins, and (ii) quorum quenching with increased lactone enzymes abundance and decreased AHLs concentration. These findings offer valuable insights that can significantly contribute to the advancement of this technology with membrane fouling control.