Method For Removal Research Articles

Z-scheme heterojunction of TiO2/NH2-MIL-125(Ti) growing on carbon fibers cloth: Photocatalytic degradation of tetracycline and toxicity analysis

Photocatalysis stands out as a promising and eco-friendly method for antibiotics removal, yet traditional photocatalysts, mainly in powder form, are often prone to detachment and loss, making them difficult to recycle and reuse. In this work, we address this challenge by using carbon fiber (CF) cloth with a large area as a carrier for catalysts. To improve the photocatalytic efficiency, we synthesized TiO2 nanorods on the surfaces of CF cloth and incorporate NH2-MIL-125 (Ti) on them, thus the Z-scheme heterojunctions CF/TiO2/NH2-MIL-125(Ti) was obtained. In order to fully understand the structural properties and performance advantages of CF/TiO2/NH₂-MIL-125 (Ti) composites, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), X-ray photoelectron spectroscopy (XPS), UV–visible diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy (PL), Brunauer-Emmett-Teller (BET), Mott-Schottky (M-S) and valence band X-ray photoelectron spectroscopy (VB-XPS). Due to the special electronic transmission path of the Z-scheme heterojunctions, the CF/TiO2/NH2-MIL-125(Ti) composite achieve 95.30 % degradation of tetracycline (TC) within 210 min. The composite also shows exceptional reusability, with a degradation rate of 93.55 % maintained even after four cycles. Finally, we proposed a pathway and catalytic process for the decomposition of TC by CF/TiO2/NH2-MIL-125(Ti) and performed toxicity assessments of TC and its precursors using T.E.S.T. software. This novel photocatalyst composite offers a green and efficient approach for treating antibiotic wastewater, presenting a significant advancement in environmental remediation strategies.

Averaging fractional Fourier domains for background noise removal applied to digital lensless holographic microscopy

A background noise removal method based on averaging fractional Fourier domains is presented. The method is applied to Digital Lensless Holographic Microscopy (DLHM) intensity reconstructions, where the background is perturbed by the weak yet detrimental presence of information of the twin image. A set of fractional Fourier domains of a DLHM intensity reconstruction is computed and thereafter averaged leading to a sensible reduction of the background noise and, therefore, an increase in the overall contrast of the resulting image. The maximum reach of the fractional rotations used in the method is determined by measuring the spatial resolution in a regular star test target such that the spatial resolution is kept within the span of interest for a given application. The set of images to be averaged is composed of fractional rotations of the original intensity reconstruction that are smaller than the previously determined maximum reach. The number of fractional rotations that are finally averaged is determined by the sought increase in the contrast of the resulting image. Experimental samples of micrometer-sized objects and an intricate biological specimen have been used to validate the proposal.

Preparation of NH2-MIL-101(Fe) Metal Organic Framework and Its Performance in Adsorbing and Removing Tetracycline.

Tetracycline's accumulation in the environment poses threats to human health and the ecological balance, necessitating efficient and rapid removal methods. Novel porous metal-organic framework (MOF) materials have garnered significant attention in academia due to their distinctive characteristics. This paper focuses on studying the adsorption and removal performance of amino-modified MIL-101(Fe) materials towards tetracycline, along with their adsorption mechanisms. The main research objectives and conclusions are as follows: (1) NH2-MIL-101(Fe) MOF materials were successfully synthesized via the solvothermal method, confirmed through various characterization techniques including XRD, FT-IR, SEM, EDS, XPS, BET, and TGA. (2) NH2-MIL-101(Fe) exhibited a 40% enhancement in tetracycline adsorption performance compared to MIL-101(Fe), primarily through chemical adsorption following pseudo-second-order kinetics. The adsorption process conformed well to Freundlich isotherm models, indicating multilayer and heterogeneous adsorption characteristics. Thermodynamic analysis revealed the adsorption process as a spontaneous endothermic reaction. (3) An increased adsorbent dosage and temperature correspondingly improved NH2-MIL-101(Fe)'s adsorption efficiency, with optimal performance observed under neutral pH conditions. These findings provide new strategies for the effective removal of tetracycline from the environment, thus holding significant implications for environmental protection.

Innovative Adsorbents for Pollutant Removal: Exploring the Latest Research and Applications.

The growing presence of diverse pollutants, including heavy metals, organic compounds, pharmaceuticals, and emerging contaminants, poses significant environmental and health risks. Traditional methods for pollutant removal often face limitations in efficiency, selectivity, and sustainability. This review provides a comprehensive analysis of recent advancements in innovative adsorbents designed to address these challenges. It explores a wide array of non-conventional adsorbent materials, such as nanocellulose, metal-organic frameworks (MOFs), graphene-based composites, and biochar, emphasizing their sources, structural characteristics, and unique adsorption mechanisms. The review discusses adsorption processes, including the basic principles, kinetics, isotherms, and the factors influencing adsorption efficiency. It highlights the superior performance of these materials in removing specific pollutants across various environmental settings. The practical applications of these adsorbents are further explored through case studies in industrial settings, pilot studies, and field trials, showcasing their real-world effectiveness. Additionally, the review critically examines the economic considerations, technical challenges, and environmental impacts associated with these adsorbents, offering a balanced perspective on their viability and sustainability. The conclusion emphasizes future research directions, focusing on the development of scalable production methods, enhanced material stability, and sustainable regeneration techniques. This comprehensive assessment underscores the transformative potential of innovative adsorbents in pollutant remediation and their critical role in advancing environmental protection.

Efficient and fast arsenate removal from water by in-situ formed magnesium hydroxide

MgO nanoparticles have good As-adsorption capacity in treating As-contaminated wastewater but suffer from high production cost. In this study, instead of using pre-formed MgO nanoparticles, we found that in-situ formed Mg(OH)2 from MgCl2 and NaOH reaction exhibited super high arsenate (As(V)) removal efficiency. Only 1.5 mmol/L of in-situ formed Mg(OH)2 could remove more than 95% As(V) within 10 min to make the As contaminated water (10 mg-As(V)/L) meet the municipal wastewater treatment standard, whereas MgO nanoparticles failed. The Mg-As sludge has an amorphous crystal structure while no Mg(OH)2 phase could be observed. As(V) existed uniformly within the sludge which was confirmed by elemental mapping. A precipitation-adsorption-coagulation mechanism might exist, which could relieve the restriction of limited surface area of solid MgO adsorbents. This study not only reveals an applicable method for efficient removal of trace level As(V) from water but also implies the huge potential of in-situ formed adsorbents in water treatment.

The Use of Some Species of Bacteria and Algae in the Bioremediation of Pollution Caused by Hydrocarbons and Some Heavy Metals in Al Asfar Lake Water

Pollution is the biggest environmental and health threat in the world. Conventional treatments of polluted habitats require the removal of pollutants contaminating the environment, but removal methods are costly and involve high power consumption. This research aims to investigate the potential for bioremediation and proposes an alternative source for implementing it that is cheaper and more environmentally friendly. The phycobioremediation experiment used hydrocarbon- and heavy-metal-polluted water from Al Asfar Lake, AlAhsa, KSA. The isolation and characterization of the lake’s predominant microalgae and associated bacteria were carried out. Monoalgal cultures of the dominant genera of algae were employed for the treatment of contaminated water and soil samples. The concentrations of the heavy metals and hydrocarbons in these samples were determined before and after the treatments by using atomic absorption spectroscopy (for heavy metals) and gas chromatography (for hydrocarbons). From the initial assessments, the levels of manganese, copper, and chromium were high, with chromium being the highest. Three microalgal isolates were identified: two coccoid, with one being blue-green and the other green, and one filamentous cyanobacterium. These species were the most efficient in removing heavy metals and dangerous hydrocarbons. Molecular characterization revealed Chlorella sp. and Geitlarianema sp. to be the most promising for bioremediation. The present work sheds light on the prospect of using algal and bacterial consortia for optimized, safe, and eco-friendly pollution amelioration.

Sequential use of coagulation and adsorption methods for COD removal from soft drink industry wastewater

Sequential use of coagulation and adsorption methods for COD removal from soft drink industry wastewater

Magnetic porous functional material from coal mine waste for simultaneous removal of cadmium and arsenic in water and soil: Synergistic effect of iron-containing minerals and porous structure

Heavy metals such as cadmium and arsenic (Cd/As) can cause harmful effects on human health. Coal mine waste (coal gangue) is a solid waste residue without commercial values produced abundantly in the coalfield. Hence, treating Cd and As concurrently with reutilizing coal gangue (CG) is critical to ecologically sustainable growth. This work successfully synthesized the magnetic porous functional materials (MPCG) based on CG using a two-step method for the simultaneous removal of Cd and As in water and soil. First, MPCG exhibited an irregular network porous structure. Then, it consisted of iron (Fe), mainly in magnetite, hematite, and pyrite forms. Such properties also exhibited excellent pH adaptability and coadsorption capacity by removing up to 103.79 mg g−1 and 579.43 mg g−1 for Cd(II) and As(V), respectively. There is a synergistic effect between the iron-containing minerals and porous structure to enhance the adsorption capacity of MPCG for Cd(Ⅱ) and As(Ⅴ). Several primary potential adsorption mechanisms by MPCG for Cd(Ⅱ) and As(Ⅴ) were identified. The potential mechanisms of Cd(II) adsorption mainly include ion exchange, electrostatic attraction, surface complexation and precipitation/co-precipitation, and the potential mechanisms of As(V) adsorption mainly include electrostatic attraction, surface complexation and precipitation. In addition, the removal rates of MPCG for Cd and As in soil were as high as 44.78 and 38.44 %, respectively. In conclusion, MPCG has excellent potential as an efficient and environmentally compatible functional material, which provides a potential way to realize efficient heavy metal removal from our ecosystems.

Production of hydrochar from the hydrothermal carbonisation of food waste feedstock for use as an adsorbent in removal of heavy metals from water

AbstractIn this research, discarded butternut peels were converted into hydrochar products through hydrothermal carbonisation (HTC), with adjustments made to the temperature (ranging from 180 to 260℃) and residence time (spanning 45–180 min). The findings indicated that both the temperature and time of carbonisation significantly influenced the yield of hydrochar (HC), as well as its physiochemical and structural properties. Higher temperatures and prolonged residence time led to decreased yield, elevated fixed carbon content and an increased fuel ratio. Furthermore, raising the process conditions increased HHV and reduced the oxygen-containing functional groups. The HC yield dropped from 28.75 to 17.58% with increased carbonisation temperature and time. The findings of this study also suggest that modified hydrochar is a promising material for removing heavy metals from wastewater. It is a relatively low-cost and abundant material that can be produced from various biomass feedstocks, including food waste. In addition, it is a sustainable and environmentally friendly option for wastewater treatment. Hydrochar-based systems offer several advantages over traditional methods of heavy metal removal, such as chemical precipitation and ion exchange. The unique physicochemical characteristics of hydrochar, including its porous structure and oxygen-rich functional groups, offer a high surface area and more binding sites for heavy metal ions. By changing the physicochemical properties of hydrochar with chemicals like phosphoric acid, it is possible to increase its adsorption capacity. The Freundlich isotherm was the best fit for the adsorption data for all three metal ions (Pb2+, Cu2+ and Cd2+), indicating that the adsorption process is multilayer and heterogeneous.

Dry reforming of toluene over Ni/pyrochlore catalysts with A-site Sr doping

Dry reforming with CO2 is one potential method for tar removal and further production of syngas in biomass gasification, but the crucial catalysts with good reaction characteristics are still being developed. In the work, Ni/pyrochlore was proposed to be utilized as catalysts in the dry reforming of tar, and thermodynamic calculation, reaction progress test, and materials characterization were conducted to reveal dry reforming characteristics over Ni/pyrochlore catalysts and the reaction mechanism behind. Results show that YS0.2C catalyst exhibits the best activity (toluene and CO2 conversion of 70.1% and 79.5%) and stability among all catalysts under the optimized conditions of 700 °C with a CO2/toluene molar ratio of 7. Analysis on physicochemical properties of the catalysts indicate Sr doping can effectively promote catalytic reforming by enhanced interaction between Ni and support, CO2 adsorption and oxygen mobility. The work offers a promising catalyst type in improving tar removal by dry reforming.

Experimental study of high-pressure ultrasound-assisted oxidative desulfurization (UAOD) and sulfone adsorption/desorption using zeolite-13X

The sulfurous compounds in natural gas liquids should be reduced to the extent of satisfying the standard recipes due to corrosion, poisoning of catalysts in downstream processes, reduction in the quality of hydrocarbon products and environmental issues. Ultrasound-assisted oxidative desulfurization is an emerging method for sulfur removal from natural gas liquids. Since natural gas liquids exist in the liquid form of hydrocarbons at high pressures and ambient temperature (25 °C), this work aims to investigate the optimal conditions governing ultrasound-assisted oxidative desulfurization for various sulfurous compounds including mercaptan, sulfide and thiophene at high pressure and finally to appraise the adsorption of oxidized sulfurs and the regeneration of the adsorbent using elution with hot water. So, the effects of sulfur content and ultrasonication time were evaluated at 30 bar. Results showed that as the initial sulfur concentration in normal heptane was increased from 0.00 to 3000 ppmS, the sulfur removal efficiency was enhanced by less than 2 % of 95.9 % and of course, the increased ultrasonication time improved the sulfur removal efficiency. Next, results of the sulfone adsorption using zeolite-13X at 30 bar in continuous mode confirmed that the breakthrough time was reduced from 63 to 12 min as the weight hourly space velocity was increased from 5 to 20 h−1 and pursuantly, the mass transfer zone diminished. Besides, the breakthrough time decreased by 45 - 10 min for increasing the initial sulfur content from 200 to 1000 ppmS. Changing the pressure of the adsorption process from 1 to 30 bar caused the improvement of sulfone adsorption capacity by approximately 3.75 times. In continued, the regeneration of zeolite-13X contaminated with sulfone by flowing hot water was evaluated and the zeolite-13X bed was completely regenerated.

Effect of calcium hydroxide and calcium hydroxide nanoparticles used as intracanal drugs after manual and ultrasonic removal on the bond strength of a new sealer with a pozzolan base (Endoseal mineral trioxide aggregate)

ABSTRACT Aim: The adhesion ability of filling materials to the root canal wall can be affected by the intracanal medicaments. The present study investigated the effect of pretreatment with nano-calcium hydroxide and calcium hydroxide on the bond strength of Endoseal mineral trioxide aggregate (MTA) to root canal dentin. Materials and Methods: Fifty maxillary incisor teeth were randomly divided into two experimental groups (n = 20) and a control group (n = 10) after decoronation near the cementoenamel junction and root canal instrumentation according to the type of intracanal medicament (calcium hydroxide and nano-calcium hydroxide). Each experimental group was divided into two subgroups based on manual and ultrasonic drug removal methods. After removing intracanal medicaments and irrigating them, all the groups were obturated with gutta-percha and Endoseal MTA sealer. Then, the samples were sectioned into cross-sections with a thickness of 2 mm using a diamond disc, and the push-out bond strength test was performed on them. Results: The results showed no significant difference in the mean Endoseal MTA bond strength in terms of the type of intracanal medicament and the method used to remove it from the canal (P > 0.05). Conclusion: Using the ultrasonic method compared to the manual method in removing intracanal medicament resulted in no significant difference in the strength of the Endoseal MTA bond. Furthermore, the effect of nanoparticle calcium hydroxide on Endoseal MTA bond strength was not different compared to the conventional type of this medication.

Comparing efficacies of various papain-based enzyme agents and 2.4% sodium hypochlorite gel in chemomechanical caries removal: a randomized controlled trial

ObjectiveThis study aimed to evaluate and compare the efficacies of Papacarie Duo gel, Brix 3000, Selecti-Solve gel, 2.4% sodium hypochlorite gel, and conventional rotary-mechanical method in caries removal and to evaluate the patient comfort.MethodsIt was a single-blinded, randomized, parallel-group, active-controlled trial with five arms. It was conducted at the Department of Restorative Dentistry and Endodontics, Damascus University. Seventy-five specimens were randomly allocated into five groups: chemomechanical caries removal (CMCR) using Selecti-Solve gel (G1), BRIX3000 (G2), Papacarie DUO gel (G3), or 2.4% sodium hypochlorite gel (G4), and caries excavation using conventional rotary-mechanical method (G5) (control group). The trial considered healthy patients aged 18–40. Permanent molars with class I carious lesions extending to the middle third of dentin with no pulpal and/or periodontal pathology were included. The efficacy of caries removal was considered the primary outcome measure, and the secondary outcome measures were treatment time, volumetric measurement of the cavity, and pain assessment.ResultsThe majority (73.30%) of cases from BRIX3000 and conventional rotary-mechanical method groups showed complete caries removal (p = 0.982). The mean time of caries removal was the highest (17.45 ± 4.42) in the 2.4% sodium hypochlorite gel group (p < 0.05), and the lowest (6.33 ± 1.69) was in the conventional rotary-mechanical method group (p < 0.05). The mean cavity volume was the highest (18.97 ± 9.76) in the Papacarie DUO gel group, and the lowest (14.87 ± 4.76) was in the 2.4% sodium hypochlorite gel group (p = 0.506). The conventional rotary-mechanical group exhibited the highest mean score (5.40 ± 1.72) of pain (p < 0.05). However, the mean score (2.67 ± 1.11) of pain reported reduced in the BRIX3000 group.ConclusionsCMCR agents could be a potential substitute for conventional rotary instrumentation methods, taking into account the long working time.

Measuring enhanced weathering: inorganic carbon-based approaches may be required to complement cation-based approaches

The removal of atmospheric carbon dioxide (CO2) is now essential to meet net zero goals and limit the impacts of climate change. Enhanced weathering is a method of sequestering CO2 that involves the distribution of finely ground silicate rocks over agricultural land. The weathering of these silicate rocks releases cations into solution which can balance dissolved inorganic carbon, effectively removing CO2 from the atmosphere. Despite being a promising method of carbon dioxide removal (CDR), enhanced weathering has been limited by uncertainty surrounding the measurement of CO2 sequestration. This study compares current measurement approaches that focus on quantifying inorganic carbon and cations within the soil and leachate. Cation-based calculations of CDR were compared to inorganic carbon-based calculations of CDR and soil results were compared to leachate results. The recovery rate of cations in the soil fraction was also tested. Three different ground silicate minerals/rocks – basalt, olivine and wollastonite, were mixed with two different soils and were allowed to weather over 16 weeks in 320 pots with and without plants under different watering regimes and the application of an acidifying fertiliser. Soil and leachate samples were analysed for cations by ICP-OES and inorganic carbon by direct CO2 analysis after acidification and total alkalinity titration (in leachate only). The results indicate that the soil retains most enhanced weathering products through the cation exchange reactions. CDR estimated by cations is often greater than CDR estimated by inorganic carbon. Measurement approaches to estimate cations are susceptible to incomplete or improper accounting through the under-extraction of cations stored within the soil-exchangeable pool, the activity of non-carbonic acids and CO2 outgassing. Inorganic carbon-based measurements, including direct inorganic carbon and total alkalinity analysis, are also complicated by the potential for CO2 loss through carbonate precipitation and re-equilibration. Therefore, inorganic carbon-based approaches and cation-based approaches should be reconciled to validate the estimation of CDR. The inorganic carbon-based estimation of CDR in leachate should equal the cation-based estimation of CDR in leachate—which will be achieved after quantification or estimation of the natural mechanisms that affect each approach. These findings will support the development of accurate measurement processes for enhanced weathering.

Evaluation of chemical mechanical polishing characteristics using mixed abrasive slurry: A study on polishing behavior and material removal mechanism

Chemical mechanical polishing (CMP) is currently the most widely used method for material removal and surface planarization of glass. An environmentally friendly method of improving polishing performance by using a mixed abrasive slurry of ceria and diamond was proposed in this study. The results of polishing experiments showed that compared with single ceria abrasive, the materials removal rate (MRR) of the mixed abrasive slurry increased from 82.7 nm/min to 109.6 nm/min, while the surface roughness (Ra) decreased from 26.4 nm to 0.6 nm after polishing. An amorphous reaction layer formed during the CMP process was observed directly using transmission electron microscopy. Thermodynamic analysis was conducted to investigate the interfacial chemical reactions during the polishing process. A model was proposed to describe the mechanism of the materials removal.

Dentine surface morphology according to caries removal method and subsequent acid etching.

Dentine surface morphology according to caries removal method and subsequent acid etching.

Comparison of pain and efficacy of caries removal using tungsten carbide bur versus chemomechanical agent (Brix Gel): A randomized controlled trial.

Objective: To compare the pain response and efficacy of caries removal using tungsten carbide burs with that of using Brix Gel as a chemomechanical caries removal agent. Study Design: Randomized Controlled Trial. Setting: Department of Operative Dentistry, PIMS, Islamabad. Period: November 2023 to April 2024. Methods: Conducted on 40 participants were selected using a non-probability technique. Participants aged 12 to 65 years with open occlusal carious lesions involving dentin were included. Patients with symptoms of pulpitis, caries affecting maxillary or mandibular anterior teeth, severe systemic illnesses, allergies, sensitivities, or pregnancy/lactation were excluded. Caries removal methods were randomly assigned. Pain levels were assessed using a Visual Analog Scale (VAS), and caries removal efficacy was evaluated. Statistical analysis was done using chi-square and independent samples t test. Results: Among the 40 participants, 47.50% were female, and the mean age was 36.30±15.57 years. Mandibular molars were the most commonly affected teeth (n=24, 60%). No significant difference in age or gender distribution was observed between the two groups. The chemomechanical method resulted in significantly lower pain scores compared to carbide bur (2.59 ± 1.34 vs. 4.44 ± 1.61, p &lt; 0.001). Pain severity also differed significantly between groups, with more mild pain reported in the chemomechanical group (80.00% vs. 5.00%, p &lt; 0.001). However, caries removal efficacy did not significantly differ between the two methods (p = 0.48). Conclusion: Chemomechanical caries removal using Brix Gel demonstrated superior pain management compared to carbide bur. While both methods showed similar efficacy in caries removal, the chemomechanical approach may offer better patient comfort during the procedure.

Pubic hair removal methods and associated factors on female sexuality in Fayoum Governorate, Egypt

Background Pubic hair removal (PHR) is a popular practice among women. They remove pubic hair by different methods, usually for visual, esthetic, or psycho-sexual aspects, as being more attractive and feminine to affect their sexual life. Objectives To assess the impact of different methods of PHR on sexual function among sexually active females in Fayoum Governorate, Egypt. And to understand factors affecting the choice of methods used in this grooming practice. Patients and methods This cross-sectional study included 500 sexually active women who completed the study structured questionnaire, which included demographics, reproductive and medical history data, assessment of sexual function in the past 4 weeks using Female Sexual Function Index (FSFI), PHR items, and the Patient Health Questionnaire depression scale-9 in the last 2 weeks. Results Almost all the participants (99.2%) preferred to remove pubic hair, and the most frequently mentioned method is shaving and creams (43.8%). The prevalence of female sexual dysfunction was 50.5% of our participants. There was a significant difference in the mean FSFI scores between different methods of PHR; with laser, users, had higher FSFI scores of arousal, lubrication, and satisfaction domains (P&lt;0.05). Wax or sweet users and laser users were more satisfied with their body image than shaving users. Conclusions Female sexual dysfunction is a widespread problem; it may result in depression and may be affected by the type of method used for PHR. Laser users had better sexual functions than users of other methods.

Biosorptive removal of toxic nitrate ion from wastewater using Albizia lebbeck seed pods: Isotherm and equilibrium studies

A major environmental issue that contaminates drinking water and endangers human health is nitrate pollution. In this study, goethite, citric acid, tartaric acid was employed to modify Albizia lebbeck seed pod for the biosorption of nitrate ion. The developed unmodified Albizia lebbeck (UALB), citric acid modified Albizia lebbeck (CALB), tartaric acid modified Albizia lebbeck (TALB), and goethite acid modified Albizia lebbeck (GALB) were characterized using scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR), and point of zero charge (pHpzc) to determine the structural morphology, functional group, and adsorbent surface charge. The adsorption nitrate ion onto the biosorbents was found to be dependent on the operating parameters. The findings revealed that the maximum percentage removal of nitrate ion was 80.8 % at pH 7 for UALB, 80.3 % at pH = 4.0 for CALB, 70.30 % at pH = 3.0 for TALB and 76 % at pH 7 for GALB. The adsorption experimental data for nitrate ion adsorption onto ULAB, CALB, TALB, and GALB were best described by the Langmuir isotherm model. The UALB exhibited the highest Langmuir monolayer adsorption capacities with a value of 344.827 mg/g. Therefore, the unmodified form of Albizia lebbeck (UALB) which is economical, and sustainable provides an efficient alternative method for nitrate removal in aqueous environment.

Effects of surfactants, ion valency and solution temperature on PFAS rejection in commercial reverse osmosis (RO) and nanofiltration (NF) processes

Per- and polyfluoroalkyl substances (PFAS) have garnered attention as a pressing environmental issue due to their enduring presence and suspected adverse health effects. This study assessed the rejection or removal efficacy of PFAS by commercial reverse osmosis (RO) and nanofiltration (NF) membranes and examined the impacts of surfactants, ion valency and solution temperature that are inadequately explored. The results reveal that the presence of cationic surfactants such as cetyltrimethylammonium bromide (CTAB) increased the rejection of two selected PFAS compounds, perfluorooctanoic acid (PFOA) and perfluorobutanoic acid (PFBA), by binding with negatively charged PFAS and preventing them from passing through membrane pores via size exclusion, whereas the presence of anionic surfactants such as sodium dodecyl sulfate (SDS) increased the PFAS rejection because the increased electrostatic repulsion prevented PFAS from approaching and adsorbing onto the membrane surface. Moreover, aqueous ions (e.g., Al3+ and PO43−) with higher ion valency enabled higher rejection of PFOA and PFBA through increased effective molecular size and increased electronegativity. Finally, only high solution temperature at 45 °C significantly reduced PFAS rejection efficiency because of the thermally expanded membrane pores and thus the increased leakage of PFAS. Overall, this research provides valuable insights into the various factors impacting PFAS rejection in commercial RO and NF processes. These findings are crucial for developing efficient PFAS removal methods and optimizing existing treatment systems, thereby contributing significantly to the ongoing efforts to combat PFAS contamination.