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Short-chain per and polyfluoroalkyl substances (PFAS) have been found to be relatively high in water treatment systems compared to long-chain PFAS because of the unsatisfactory adsorption efficiency of short-chain PFAS. Knowledge about why short-chain PFAS are less removed by porous carbon is very limited. The study focused on providing causal mechanisms that link the low adsorption of short-chain PFAS and proposing an improved method for removing both short- and long-chain PFAS. The long-chain PFAS with higher hydrophobicity diffused more quickly than the short-chain PFAS due to stronger partitioning driving forces. In the initial adsorption stage, therefore, pores of activated carbon were blocked by long-chain PFAS, which makes it difficult for the short-chain PFAS to enter the internal pores. Although several short-chain PFAS diffuse into the pores, the relatively more hydrophilic short-chain congeners cannot be fully adsorbed on activated carbon due to limited positively charged sites. Moreover, compared to larger particle sizes, smaller activated carbon particles have shorter pore channels near the surface, reducing the risk of pore-blocking and ensuring the pores remain accessible for more efficient adsorption. Additionally, these smaller particles offer a greater external surface area and more functional groups, which enhance the adsorption capacity. It indicates that the smaller particle size of activated carbon would have a positive effect on the short-chain PFAS removal., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

In-situ remediation of total petroleum hydrocarbon (TPH) contaminated soils via Fenton oxidation is a promising approach. However, determining the proper injection amount of H 2 O 2 and Fe source over the Fenton reaction in the complex geological conditions for in-situ TPH soil remediation remains a daunting challenge. Herein, we introduced a practical and novel approach using soft computational models, a multilayer perception artificial neural network (MPLNN), for predicting the TPH removal performance. In this study, we conducted 48 sets of TPH removal experiments using Fenton oxidation to determine the TPH removal performance of a wide range of different ground conditions and generated 336 data points. As a result, a negative Pearson correlation coefficient was obtained in the Fe injection mass and the natural presence of Fe mineral in the soil, indicating that the excess of Fe could significantly retarded the TPH removal performance in the Fenton reaction. In addition, the MPLNN model with 6-6-1 training using Scaled conjugate gradient backpropagation (SCG) with tangent sigmoid as the transfer function demonstrated a high accuracy for TPH removal prediction with the correlation determination of 0.974 and mean square error value of 0.0259. The optimized MPLNN model achieved less than 20% error for predicting TPH removal performance in actual TPH-contaminated soil via Fenton oxidation. Hence, the proposed MPLNN can be useful in improving the Fenton oxidation of TPH removal performance in-situ soil remediation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Bisphenol A (BPA), a widely recognized endocrine disrupting compound, has been discovered in drinking water sources/finished water and domestic wastewater influent/effluent. Numerous studies have shown photocatalytic and electrocatalytic oxidation to be very effective for the removal of BPA, particularly in the addition of graphene/graphene oxide (GO)-based nanocatalysts. Nevertheless, the photocatalytic and electrocatalytic degradation of BPA in aqueous solutions has not been reviewed. Therefore, this review gives a comprehensive understanding of BPA degradation during photo-/electro-catalytic activity in the presence of graphene/GO-based nanocatalysts. Herein, this review evaluated the main photo-/electro-catalytic degradation mechanisms and pathways for BPA removal under various water quality/chemistry conditions (pH, background ions, natural organic matter, promotors, and scavengers), the physicochemical characteristics of various graphene/GO-based nanocatalysts, and various operating conditions (voltage and current). Additionally, the reusability/stability of graphene/GO-based nanocatalysts, hybrid systems combined with ozone/ultrasonic/Fenton oxidation, and prospective research areas are briefly described., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The existence of pollutants, such as toxic organic dye chemicals, in water and wastewater raises concerns as they are inadequately eliminated through conventional water and wastewater treatment methods, including physicochemical and biological processes. Ultrasonic treatment has emerged as an advanced treatment process that has been widely applied to the decomposition of recalcitrant organic contaminants. Ultrasonic treatment has several advantages, including easy operation, sustainability, non-secondary pollutant production, and saving energy. This review examines the elimination of dye chemicals and categorizes them into cationic and anionic dyes based on the existing literature. The objectives include (i) analyzing the primary factors (water quality and ultrasonic conditions) that influence the sonodegradation of dye chemicals and their byproducts during ultrasonication, (ii) assessing the impact of the different sonocatalysts and combined systems (with ozone and ultraviolet) on sonodegradation, and (iii) exploring the characteristics-based removal mechanisms of dyes. In addition, this review proposes areas for future research on ultrasonic treatment of dye chemicals in water and wastewater., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Influence of the cosolvent on the sorption of organic acids on biochar has not been well understood. For this purpose, the sorption (log K m , L kg -1 ) of three aromatic acids (benzoic acid (BA, pK a  = 4.20), 1-naphthoic acid (1-NAPA, pK a  = 3.70), and 9-anthroic acid (9-ANTA, pK a  = 3.65) was evaluated as a function of methanol volume fraction (f c  = 0.0, 0.25, and 0.5), liquid pH (2.5 and 7.0), ionic composition (CaCl 2 and KCl) and ionic strength (0.005 M, 0.5 M, and 1 M CaCl 2 ). A giant Miscanthus-derived biochar (ZPC of 2.86) was used as the sorbent. For all solutes, the sorption coefficients (log K m ) measured at pH 2.5 (i.e., pH < pK a ) tended to decrease with increasing f c , as expected from the cosolvency model, while the result obtained at pH 7.0 was not fully explained by the same model. The log K m of 1-NAPA in the CaCl 2 system was always greater than in the KCl system (p < 0.05) and the impact became pronounced at high pH (>pK a ) with increasing f c . Increasing the Ca 2+ concentration at f c  = 0.0 (from 0.005 M to 1 M) enhanced the value by 0.32 log unit of K m . These phenomena indicate a significant role of dissolved Ca 2+ in the liquid phase, most likely due to the formation of cation bridges between aromatic carboxylates and the biochar surface (i.e., [R-COO - -Ca 2+ ]-{Biochar - }). A decrease in the dielectric constant of the methanol mixture could fortify the formation of this bridge. Regardless of the degree of cosolvency power (σ), as the number of aromatic rings of solutes increases, K m decreases in the order BA > 1-NAPA > 9-ANTA, where f c  = 0.0. In conclusion, the sorption potential of biochar can be significantly weakened by increasing pH and f c , and in the absence of a divalent cation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Boron nitride (BN) coupled with various conventional and advanced photocatalysts has been demonstrated to exhibit extraordinary activity for photocatalytic degradation because of its unique properties, including a high surface area, constant wide-bandgap semiconducting property, high thermal-oxidation resistance, good hydrogen-adsorption performance, and high chemical/mechanical stability. However, only limited reviews have discussed the application of BN or BN-based nanomaterials as innovative photocatalysts, and it does not cover the recent results and the developments on the application of BN-based nanomaterials for water purification. Herein, we present a complete review of the present findings on the photocatalytic degradation of different contaminants by various BN-based nanomaterials. This review includes the following: (i) the degradation behavior of different BN-based photocatalysts for various contaminants, such as selected dye compounds, pharmaceuticals, personal care products, pesticides, and inorganics; (ii) the stability/reusability of BN-based photocatalysts; and (iii) brief discussion for research areas/future studies on BN-based photocatalysts., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

This is the first report to evaluate the potential effects of microplastics (MPs) on wild wharf roaches (Ligia exotica) in a shoreline habitant. L. exotica is an important plastic detritus consumer in coastal area. A survey was conducted from May to June in the years 2019 and 2020 in two South Korean nearshore sites: Nae-do (as MPs-uncontaminated) and Maemul-do (as MPs-contaminated). MPs (>20 μm in size) were detected highly in gastrointestinal tracts of the L. exotica from Maemul-do, at an average level of 50.56 particles/individual. They were detected in much lower levels in the L. exotica from Nae-do. at an average rate of 1.00 particles/individual. The polymer type and shape were dominated by expanded polystyrene (EPS, 93%) and fragment (99.9%) in L. exotica from Maemul-do. Especially, Hexabromocyclododecanes, brominated flame retardants added to EPS, have been detected highly in L. exotica from Maemul-do (630.86 ± 587.21 ng/g l. w.) than those of Nae-do (detection limit: 10.5 ng/g l. w). Genome-wide transcriptome profiling revealed altered expression of genes associated with fatty acid metabolic processes, the innate-immune response-activating system and vesicle cytoskeletal trafficking in L. exotica from Maemul-do. The activation of the p53 signaling pathway (which is related to proteasome, ER regulation and cell morphogenesis) is likely to be involved in the EPS-uptake of wild L. exotica. Four neurosteroids were also detected in head tissue, and cortisol and progesterone concentrations differed significantly in L. exotica from Maemul-do. Our findings also suggest that resident plastic detritus consumer might be a useful indicator organism for evaluating pollution and potential effects of environmental microplastics., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Along with bisphenol-A (BPA), conventional phthalate esters (PAEs) have been reported as environmental hormones, despite their functional usefulness as plasticizers. Nevertheless, they are frequently found in various products, including children's utensils and toys made of poly (vinyl chloride). This is tremendously important because PAEs are harmful to infants. In addition, gel/slime-type toys made of poly (vinyl alcohol) are currently popular for developing infant' tactile senses. In this study, we developed a method to qualitatively and quantitatively detect PAEs in gel/slime-type toys mimicking, infants playing with them in a bathtub. As a result, 1,2-cyclohexanedicarboxylic acid diisononyl ester (DINCH), one of the PAE alternatives, transferred into the water from the toys and was detected most commonly (108-719 μg g -1 ; 0.01-0.07 wt%) among PAEs. The detected DINCH levels were below the universally accepted levels for PAEs (0.1 wt%). However, the amount of DINCH detected could still be toxic, in accordance with toxicity tests using water fleas. Furthermore, unpleasant odors were emitted when the toys containing toxic volatile organic compounds were unpacked. This is the first study to develop a method to analyze PAE in gel/slime-type toys and determine that alternatives to conventional PAEs cannot be unconditionally regarded as safe chemicals. Therefore, the revised standards for regulating PAEs and their alternatives must be reconsidered., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Photocatalytic removal of toxic contaminants is one of the emerging techniques for water remediation, but it suffers from low redox ability, charge recombination and poor light harvesting efficiency. The present work reports a simultaneous S-scheme promoted by CeVO 4 /g-C 3 N 4 /Ag@AgVO 3 . The formation of the S-scheme mechanism enhanced the generation of photogenerated carriers and also improved the redox ability of the electrons and holes in the reduction and oxidation photocatalysts. The ternary demonstrated remarkable photo switching properties along with efficient charge separation which was achieved through dual interfacial interaction within the ternary (Ag@AgVO 3 /g-C 3 N 4 and CeVO 4 /g-C 3 N 4 ). The heterojunction formation was verified through the shift in binding energy spectra in the X-ray Photoelectron spectroscopy (XPS), and high-resolution transmission electron microscopy analysis (HR-TEM). The ternary demonstrated reduced PL intensity, width of space charge region and an upsurge in photogenerated current density in the order of 93 μA/cm2 (∼6X higher than all the pristine). This resulted in efficient removal of methyl orange, methylene blue and endocrine disruptive bisphenol-A with a removal rate of 0.02 min -1 , 0.03 min -1 and 0.0087 min -1 and an apparent quantum yield of 4.6 × 10 -9 (Methylene Orange), 6.89 × 10 -9 (Methylene Blue) and 2 × 10 -9 (Bisphenol A/H 2 O 2 )., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Atmospheric non-thermal dielectric barrier discharge (DBD) plasma has gained considerable attention due to its cost-efficiency, environmental friendliness, and simplicity. However, certain deficiencies restrict its broad application. Herein, the DBD plasma was used to disrupt three model pharmaceutically active compounds (PhACs), sulfamethoxazole (SMX), ibuprofen (IBP), and norfloxacin (NFX), by varying parameters, such as gas type (Ar, N 2 , O 2 , and air) and flow rate (1-4 L min -1 ). The air plasma discharge had the highest degradation efficiency, and the air flow rate was optimized at 2 L min -1 . However, only 10% of IBP was removed by the sole plasma, whereas NFX and SMX were entirely removed after 30 min. Since the air plasma discharge generates reactive oxygen and nitrogen species in a chained reaction, the remaining NO 2 - and NO 3 - in the aqueous phase were problematic. Therefore, by coupling plasma with electrolysis using Cu/reduced Cu nanowire (R-CuNw) as the anode/cathode, all three PhACs were removed within 30 min, and NO 2 - and NO 3 - were completely reduced to NH 3 with cathodic reduction. Moreover, the electrical energy per order (E EO, 0.04 kWh L -1 ) and treatment cost (0.003 USD L -1 ) were much lower than those of the single system. This system demonstrates great potential for water remediation, and the production of NH 3 as a value-added by-product remarkably improves its practicality and is of great importance in agriculture and energy-related industries., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

As plastic consumption has increased, environmental problems associated with the accumulation of plastic wastes have started to emerge. These include the non-degradability of plastic and its disintegration into sub-micron particles. Although some biodegradable plastic products have been developed to relieve the landfill and leakage burden, a significant portion of discarded plastics are inevitably still incinerated. The concern here is that incinerating plastics may result in the emission of toxic volatile organic compounds (VOCs). Moreover, lack of policy and the limited market share contributes to the indiscriminate discarding of biodegradable plastics, whereby it is mixed and subsequently incinerated with non-degradable plastics. The aim of this study was therefore to qualitatively and quantitatively analyze the VOCs emitted from both non-degradable and biodegradable plastics during combustion employing gas chromatography mass spectrometry. Here, non-degradable poly(vinyl chloride) and poly(ethylene terephthalate) emitted 10-115 and 6-22 ppmv of VOCs, respectively. These emission levels were more than 100 times higher than the VOC concentrations of 0.1-0.5 and 0.1-1.8 ppmv obtained for biodegradable polyhydroxyalkanoate and polylactic acid, respectively. Notably, due to the presence of a repeating butylene group in both non-degradable and biodegradable plastics, 1,3-butadiene accounted for the highest concentration among the VOCs identified, with concentrations of 6-116 ppmv and 0.5-558 ppmv obtained, respectively. During the evaluation of gas barrier films employed for food packaging purposes, non-degradable aluminum-coated multilayered films emitted 9-515 ppmv of VOCs, compared to the 2-41 ppmv VOCs emitted by biodegradable nanocellulose/nanochitin-coated films. Despite the significantly lower levels of VOCs emitted during the incineration of biodegradable plastics, this does not represent suitable waste treatment solution because VOCs are still emitted during incomplete combustion. This study aims to encourage further research into diverse combustion conditions for plastics and stimulate discussions on the fate of discarded plastics., (Copyright © 2022 The Authors. Published by Elsevier Ltd.. All rights reserved.)

This study reports for the first-time the possibility of deploying gas production by thiosulfate utilizing denitrifying bacteria (TUDB) as a proxy to evaluate water toxicity. The test relies on gas production by TUDB due to inhibited metabolic activity in the presence of toxicants. Gas production was measured using a bubble-type respirometer. Optimization studies indicated that 300 mg NO 3 - -N/L, 0.5 mL acclimated culture, and 2100 mg S 2 O 3 2- /L were the ideal conditions facilitating the necessary volume of gas production for sensitive data generation. Determined EC 50 values of the selected heavy metals were: Cr 6+ , 0.51 mg/L; Ag + , 2.90 mg/L; Cu 2+ , 2.90 mg/L; Ni 2+ , 3.60 mg/L; As 3+ , 4.10 mg/L; Cd 2+ , 5.56 mg/L; Hg 2+ , 8.06 mg/L; and Pb 2+ , 19.3 mg/L. The advantages of this method include operational simplicity through the elimination of cumbersome preprocessing procedures which are used to eliminate interferences caused by turbidity when the toxicity of turbid samples is determined via spectrophotometry., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

A novel alkali diffusion reactor using ceramic porous media (ceram-ADR) was designed for the long-term remediation of acid mine drainage (AMD) without external energy. The filling material was newly applied to improve the ceram-ADR for intensive long-term treatment of acidity and metals in AMD. Activated carbon (AC), polyurethane (PU), or MgO-incorporated polyurethane (PU-MgO) were inserted as filling materials into ceram-ADR. NaHCO 3 was used as the alkaline chemical. PU did not enhance the neutralizing capacity of ADR and metal removal efficiency. Although the ceram-ADR with PU-MgO showed long-term removal efficiency for all metals up to 545 bed volumes (BVs), the effluent pH complied with the mineral mining and processing effluent guidelines during 45 BVs. Ceram-ADR with AC enhanced the long-term treatment (up to a year) of metals and acidity in AMD. Mn concentration in the effluent discharged from ceram-ADR exceeded the mineral mining and processing effluent guidelines, followed by Zn, Al, and Fe. The main removal mechanism for metals was precipitation as a metal hydroxide or metal carbonate. The ion exchange of metal ions on the surface of ceramic porous media and AC can influence the adsorption behavior, which is responsible for 15.3% of the total removal of metals. The ceram-ADR with AC could be reused at least five times with no appreciable loss in activity. These results highlight the hybrid operation of ADR for the best performance in mining areas where the passive and active system are insufficient because of low efficiency, budget limitations, and geological sites., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Contaminants of emerging concerns such as endocrine-disrupting compounds (EDCs) and pharmaceuticals/personal-care products (PPCPs) constitute a problem since they are not completely eliminated by traditional water and wastewater treatment methods. Non-thermal plasma (NTP) is considered as one of the most favorable treatment methods for the removal of organic contaminants in water and wastewater. The degradation of selected EDCs and PPCPs of various classes was reviewed, based on the recent literature, to (i) address the effect of the main NTP treatment parameters (water quality and NTP conditions: pH, initial concentration, temperature, background common ion, NOM, scavenger, gas type/flow rate, discharge/reactor type, input power, and energy efficiency/yield) on the degradation of contaminants and their intermediates, (ii) assess the influences of different catalysts and hybrid systems on degradation, (iii) describe EDC and PPCP degradation along with their properties, and (iv) evaluate mineralization, pathway, and degradation mechanism of selected EDCs and PPCPs for different cases studied. Furthermore, areas of potential research in NTP treatment for the degradation of EDCs and PPCPs in aqueous solutions are recommended. It could be reasonably predicted that this review is valid for developing our understanding of the fundamental scientific principles concerning the catalytic NTP of EDCs and PPCPs, providing helpful and practical references for researchers and designers on the effective removal of EDCs/PPCPs and the optimized operation of catalytic NTP systems., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Thermal plasma blasting technology has been widely applied for rock cracking. Though, the application for environmental remediation has yet to be reported. Since the delivery of remediation agents into diesel contaminated clayey zones are exceptionally challenging, herein, this study explores the effect of pilot-scale thermal plasma blasting for soil fracturing and concurrently dispersing the Fenton reagent into the diesel contaminated silty soils. Six times plasma blasting with sole H 2 O 2 at 20 kV had the highest degradation of diesel (>97%) with an equilibrium time of 3 h, and the final diesel concentration was below the South Korean regulated health standard (500 mg kg -1 ). This study highlights plasma blasting able to deliver H 2 O 2 instantaneously and homogeneously into contaminated zone while promoting Fenton reaction synergism (f syn : 2.04) between H 2 O 2 and ≡Fe surface for effective remediation. Furthermore, the remediation cost (USD 4 metric ton -1 ) is much lower than most reported in situ technologies., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Adsorption is an effective method for the removal of inorganic and organic contaminants and has been commonly used as a pretreatment method to improve contaminant removal and control flux during membrane filtration. Over the last two decades, many researchers have reported the use of hybrid systems comprising various adsorbents and different types of membranes, such as nanofiltration (NF), ultrafiltration (UF), and microfiltration (MF) membranes, to remove contaminants from water. However, a comprehensive evaluation of the removal mechanisms and effects of the operating conditions on the transport of contaminants through hybrid systems comprising various adsorbents and NF, UF, or MF membranes has not been performed to date. Therefore, a systematic review of contaminant removal using adsorption-membrane hybrid systems is critical, because the transport of inorganic and organic contaminants via the hybrid systems is considerably affected by the contaminant properties, water quality parameters, and adsorbent/membrane physicochemical properties. Herein, we provide a comprehensive summary of the most recent studies on adsorption-NF/UF/MF membrane systems using various adsorbents and membranes for contaminant removal from water and wastewater and highlight the future research directions to address the current knowledge gap., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Since multilayered MXenes (Ti 3 C 2 T x , a new family of two-dimensional materials) were initially introduced by researchers at Drexel University in 2011, various MXene-based nanocomposites have received increased attention as photocatalysts owing to their exceptional properties (e.g., rich surface chemistry, adjustable bandgap structures, high electrical conductivity, hydrophilicity, thermal stability, and large specific surface area). Therefore, we present a comprehensive review of recent studies on fabrication methods for MXene-based photocatalysts and photocatalytic performance for contaminant degradation, CO 2 reduction, H 2 evolution, and N 2 fixation with various MXene-based nanocomposites. In addition, this review briefly discusses the stability of MXene-based nanophotocatalysts, current limitations, and future research needs, along with the various corresponding challenges, in an effort to reveal the unique properties of MXene-based nanocomposites., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Environmental pollution has intensified and accelerated due to a steady increase in the number of industries, and finding methods to remove hazardous contaminants, which can be typically divided into inorganic and organic compounds, have become inevitable. One of the widely used water treatment technologies is adsorption and various kinds of adsorbents for the removal of inorganic and organic contaminants from water have been discovered. Recently, MXene, as an emerging nanomaterial, has gained rapid attention owing to its unique characteristics and various applicability. Particularly, in the area of adsorptive application, MXene and MXene-based adsorbents have shown great potential in a large number of studies. In this regard, a comprehensive understanding of the adsorptive behavior of MXene-based nanomaterials is necessary in order to explain how they remove inorganic and organic contaminants in water. Adsorption by MXene-based adsorbents tends to be highly influenced by not only the physicochemical properties of these adsorbents but also water quality, such as pH value, temperature, background ion, and natural organic matter. Therefore, in this review paper, the effect of various water quality on the adsorption of inorganic and organic contaminants by various types of MXene and MXene-based adsorbents is explored. Furthermore, this review also covers general trends in the synthesis of MXene and regeneration of MXene-based adsorbents in order to assess their stability., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Porous hollow fiber polysulfone (PSf) membranes were fabricated via a phase-inversion process and their performance during ultrafiltration (UF) was evaluated. The effects of the composition and concentration (0-50%) of different bore fluid mixtures, including N-methyl-2-pyrrolidone (NMP)/water, glycerol (G)/water, and ethylene glycol (EG)/water (in comparison with pure deionized water), on the structure, physicochemical properties, and performance of the fabricated membranes was investigated. Using these various bore fluid mixtures altered the thermodynamic and kinetic properties of the phase inversion system, and changed the morphology and structure of the fabricated membranes, especially on the lumen side. Increasing concentrations of NMP, G, and EG in the bore fluid resulted in increased pore size, porosity, and hydrophilicity. These bore fluid mixtures exhibited a strong influence on the perm-selectivity of the as-spun hollow fiber membranes. The membrane fabricated using 50% NMP/water as the bore fluid mixture exhibited the highest water flux of 166.98 LMH with a bovine serum albumin rejection rate of more than 97%. Overall, this study introduces an easy and effective way to control the structure of the membrane through bore fluid modification and shows how the inner skin layer properties can have a remarkable effect on water permeance, even in the out-in filtration test., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Since MXenes (a new family of two-dimensional materials) were first produced in 2011, they have become very attractive nanomaterials due to their unique properties and the range of potential industrial applications. Numerous recent studies have discussed the environmental applications of different MXenes in adsorption, catalysis, and membranes. Only a limited number of MXene-based membrane studies have been published to date, and most have discussed only specific MXenes (i.e., Ti 3 C 2 T x ), a small number of solutes (e.g., dyes and inorganic salts), and laboratory-scale short-term experiments under limited water-quality and operational conditions. In addition, to our knowledge, there has been no review of MXene-membrane studies. It is therefore essential to assess the current status of understanding of the performance of these membranes in liquid separation and water purification. Here, a comprehensive literature review is conducted to summarize the current preparation techniques for MXene-based membranes and their applications, particularly in terms of environmental and industrial applications (e.g., water treatment and organic solvent filtration), and to direct future research by identifying gaps in our present understanding. In particular, this review focuses on several key factors, including the effects of preparation techniques on membrane properties, operational conditions, and compound properties that influence liquid separation during MXene-based membrane filtration., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

In this study, palm shell activated carbon powder (PSAC) and magnesium silicate (MgSiO 3 ) modified PSAC (MPSAC) were thoroughly investigated for fluoride (F - ) adsorption. F - adsorption isotherms showed that PSAC and MPSAC over-performed some other reported F - adsorbents with adsorption capacities of 116 mg g -1 and 150 mg g -1 , respectively. Interestingly, the MgSiO 3 impregnated layer changed the adsorption behavior of F - from monolayer to heterogeneous multilayer based on the Langmuir and Freundlich isotherm models verified by chi-square test (X 2 ). Thermodynamic parameters indicated that the F - adsorption on PSAC and MPSAC was spontaneous and exothermic. PSAC and MPSAC were characterized using FESEM-EDX, XRD, FTIR and XPS to investigate the F - adsorption mechanism. Based on the regeneration tests using NaOH (0.01 M), PSAC exhibited poor regeneration (<20%) while MPSAC had steady adsorption efficiencies (∼70%) even after 5 regeneration cycles. This is due to highly polarized C-F bond was found on PSAC while Mg-F bond was distinguished on MPSAC, evidently denoting that the F - adsorption is mainly resulted from the exchange of hydroxyl (-OH) group. It was concluded that PSAC would be a potential adsorbent for in-situ F - groundwater remediation due to its capability to retain F - without leaching out in a wide range pH. MPSAC would be an alternative adsorbent for ex-situ F - water remediation because it can easily regenerate with NaOH solution. With the excellent F - adsorption properties, both PSAC and MPSAC offer as promising adsorbents for F - remediation in the aqueous phase., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Graphene oxide (GO) and metal-organic framework (MOF) as adsorbents were applied to removal of Pb(II) with comprehensive characterizations and various experimental conditions. Various characterizations were conducted to clarify the physico-chemical properties of adsorbents. The analyses of adsorption experiments included (i) dosage amounts, (ii) isotherm and kinetic studies, and (iii) several factors related to water chemistry (i.e., solution pH, background ions, and humic acid). The maximum equilibrium adsorption capacity (q e ) for Pb(II) using the GO and MOF was 555 and 108 mg g -1 , respectively, as determined in the optimum dosage experiments. Although the surface area of the MOF (629 m 2  g -1 ) was much larger than that of the GO (19.8 m 2  g -1 ), the adsorption capacity of the MOF was five times lower due to electrical repulsion. Thus, the MOF was utilized as the control group for comparison with the GO to evaluate the adsorption mechanisms in the experiments related to surface charge (i.e., under various pH and humic acid conditions). The adsorption isotherms and kinetics model determined using GO followed the Langmuir model (R 2  > 0.99) and pseudo-second-order model (R 2  > 0.99), respectively. Additionally, three adsorption-desorption cycles were conducted with the GO adsorbent to evaluate the maintenance of the removal ratio after regeneration and the equilibrium adsorption capacity was determined. Finally, the adsorption of other heavy metals (i.e., Cu(II), Cd(II), and Zn(II)), separately and in mixtures, was also evaluated to determine the selectivity of the adsorbents., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

In this study, magnetic layered double hydroxides (mag-LDHs) were synthesized through compositing magnetite with three different metals (Mg, Cu and Al) under ultrasound (US, 100 kHz frequency and 50 W power). For the first time, mag-LDHs were applied to sonocatalytic reduction of nitrate (NO 3 - ) and the reduction mechanism were determined by conducting kinetic tests and various spectroscopic analyses. Based on the kinetic data, NO 3 - reduction and the selectivity for N 2 highly depends on the ratio between Mg/Al, solution pH and sonication frequency. The best condition for sonocatalytic denitrification was found to be pH 7 operated under 100 kHz (50% power) using the catalyst with lowest amount of Al (mag-LDH-Al 0.3 Mg 1.5 ). As a proposed mechanism, NO 3 - is initially reduced to NO 2 - by Cu 0 , and then further reduced to N 2 /NH 4 + by Mg 0 . Hypothetically Al 0 could provide sorption sites for hydrogen radicals (·H) dissociated from ultrasound, hence served as reducing sites in denitrification process. The XPS analysis showed an increased peak of Cu 0 after the sonocatalytic reduction when catalyst has lower amount of Al. The excessive hydrogen adsorbed on Al 0 might spill-over to the adjacent Cu, thus reducing the CuO into Cu 0 at high temperature created by the implosion of the microbubbles. Without the use of consumable reducing agents (i.e. H 2 gas), sonocatalytic reduction could be a potential candidate of remediation method to treat NO 3 - polluted water with high N 2 selectivity and easy magnetic recovery., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

A graphene-oxide (GO)/β-Bi 2 O 3 /TiO 2 /Bi 2 Ti 2 O 7 heterojuncted nanocomposite, designated as GBT, was synthesized via a two-step hydrothermal process. The sonocatalytic activity of the GBT was evaluated at several frequencies (28, 580, and 970 kHz) and compared with Bi-doped GO (GB) and Ti-doped GO (GT). Transmission electron microscopy images showed heterojuncted crystal structures of Bi and Ti on GO, and X-ray diffraction patterns verified that the crystal structures consisted of β-Bi 2 O 3 , TiO 2 , and Bi 2 Ti 2 O 7 nanocomposites. Energy-dispersive X-ray spectroscopy revealed a higher proportion of metal on GBT surfaces compared with GB and GT surfaces. The energy band gaps of GT, GB, and GBT were 3.0, 2.8, and 2.5 eV, respectively. Two pharmaceuticals (PhACs; carbamazepine [CBZ] and acetaminophen [ACE]) were selected and treated under sonolytic conditions at frequencies of 28, 580, and 970 kHz at a power level of 180 W L -1 . The selected pharmaceuticals, present at initial concentrations of 20 μM, were reduced by over 99% by ultrasonic irradiation in the presence of GBT. The 580 kHz treatment achieved the most rapid organic removal among the frequencies tested. The removal kinetic of CBZ was higher than that of ACE owing to its relatively high hydrophobicity. High sonocatalytic activity of GBT was observed through measurement of H 2 O 2 in solution. Because of its low band gaps and high surface activity, GBT exhibited higher sonolytic activity in removing selected PhACs than GT or GB., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Various graphene-based nanoadsorbents, including graphenes, graphene oxides, reduced graphene oxides, and their nanocomposites, have been widely studied as potential adsorbents due to their unique physicochemical properties, such as structural variability, chemical strength, low density, and the possibility of large scale fabrication. Adsorption mechanisms are governed largely by the physicochemical properties of contaminants, the characteristics of nanoadsorbents, and background water quality conditions. This review summarizes recent comprehensive studies on the removal of various inorganic (mainly heavy metals) and organic contaminants by graphene-based nanoadsorbents, and also discusses valuable information for applications of these nanoadsorbents in water and wastewater treatment. In particular, the aqueous removal of various contaminants was reviewed to (i) summarize the general adsorption capacities of various graphene-based nanoadsorbents for the removal of different inorganic and organic contaminants, (ii) evaluate the effects of key water quality parameters such as pH, temperature, background major ions/ionic strength, and natural organic matter on adsorption, (iii) provide a comprehensive discussion of the mechanisms that influence adsorption on these nanoadsorbents, and (iv) discuss the potential regeneration and reusability of nanoadsorbents. In addition, current challenges and future research needs for the removal of contaminants by graphene-based nanoadsorbents in water treatment processes are discussed briefly., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

This research investigated the removal of carbamazepine (CBZ) and diclofenac (DCF) in water using ultrasonic (US) treatment in the absence or presence of graphene oxides (GOs). Three frequencies and three pH conditions were tested (28, 580, and 1000 kHz and 3.5, 7, and 9.5, respectively). Regarding the effects of US frequency and pH, 580 kHz and pH 3.5 were more effective at removing CBZ and DCF (>86% for CBZ and >92% for DCF) than 1000/28 kHz and pH 7/9.5 within 60 min. However, sonocatalytic removal was enhanced in the presence of GOs; more than 99% CBZ and DCF removal was achieved at 580 kHz and pH 3.5 within 40 min. The sonicated GOs were more stable at 28 kHz than at higher frequencies of 580 and 10,00 kHz. The adsorption of CBZ and DCF has increased when GOs were sonicated at 28 kHz (44% and 61%, respectively) compared with 580 kHz (34% and 52%, respectively) and 1000 kHz (18% and 39%, respectively). The negative charges of GOs increased at 28 kHz (-105.1 mV), however, it decreased at higher frequencies such as 580 kHz (-71.5 mV) and 1000 kHz (-58.6 mV), which led to increased electrostatic repulsion that increased the stability of the GO particles in water. The overall enhancement in CBZ and DCF removal was due to an increase in cavitational bubbles, which in turn led to increased production of OH • and enhanced adsorption due to dispersion (resulting from US irradiation), which caused an increase in active adsorption sites of the GOs., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Expanded polystyrene (EPS) is a major component of marine debris globally. Recently, hazardous hexabromocyclododecanes (HBCDDs) were detected in EPS buoys used for aquaculture farming. Subsequently, enrichment of HBCDDs was found in nearby marine sediments and mussels growing on EPS buoys. It was suspected that EPS buoys and their debris might be sources of HBCDDs. To confirm this, the release of HBCDDs from EPS spherules detached from a buoy to seawater was investigated under field (open sea surface and closed outdoor chambers with sun exposure and in the dark) and laboratory (particle-size) conditions. In all exposure groups, initial rapid leaching of HBCDDs was followed by slow desorption over time. Abundant release of HBCDDs was observed from EPS spherules exposed to the open sea surface (natural) and on exposure to sunlight irradiation or in the dark in controlled saline water. Water leaching and UV-light/temperature along with possibly biodegradation were responsible for about 37% and 12% of HBCDDs flux, respectively. Crumbled EPS particles (≤1 mm) in samples deployed on the sea surface for 6 months showed a high degree of weathering. This implies that surface erosion and further fragmentation of EPS via environmental weathering could enhance the leaching of HBCDDs from the surface of EPS. Overall, in the marine environment, HBCDDs could be released to a great extent from EPS products and their debris due to the cumulative effects of the movement of large volumes of water (dilution), biodegradation, UV-light/temperature, wave action (shaking), salinity and further fragmentation of EPS spherules., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

We developed a single-walled carbon nanotubes (SWCNTs)-based electrochemical biosensor for the detection of Bacillus subtilis, one of the microorganisms observed in Asian dust events, which causes respiratory diseases such as asthma and pneumonia. SWCNTs plays the role of a transducer in biological antigen/antibody reaction for the electrical signal while 1-pyrenebutanoic acid succinimidyl ester (1-PBSE) and ant-B. subtilis were performed as a chemical linker and an acceptor, respectively, for the adhesion of target microorganism in the developed biosensor. The detection range (10 2 -10 10  CFU/mL) and the detection limit (10 2  CFU/mL) of the developed biosensor were identified while the response time was 10 min. The amount of target B. subtilis was the highest in the specificity test of the developed biosensor, compared with the other tested microorganisms (Staphylococcus aureus, Flavobacterium psychrolimnae, and Aquabacterium commune). In addition, target B. subtilis detected by the developed biosensor was observed by scanning electron microscope (SEM) analysis., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Triethoxyphenylsilane (TEPS)-functionalized magnetic palm-based powdered activated carbon (MPPAC-TEPS) was prepared and characterized using various spectroscopic methods, and then tested for the removal of bisphenol A, carbamazepine, ibuprofen and clofibric acid. Magnetite film on MPPAC-TEPS was homogeneously coated on the outer surface of palm-based powdered activated carbon (PPAC) through a hydrothermal co-precipitation technique. Followed by silanization of phenyl-functionalized organosilane on MPPAC's magnetic film. As results, micro/mesopore surface area and volume increased without significant pore clogging and iron (Fe) dissolution under the acidic conditions was greatly decreased. The unique structural and chemical features of MPPAC-TEPS were found to be the main reasons for the enhanced adsorption rates and removal capacities of POPs. The presence of electrolytes and different pH values greatly affected the sorption efficiencies. The dominant sorption mechanism of POPs by MPPAC-TEPS was determined to be π-π interaction (physisorption), based on thermodynamic (ΔG°) and differential scanning calorimetry (DSC). Thermal regeneration at a low temperature (350 °C) was an effective method to desorb the retained POPs and enabled to reactivate MPPAC-TEPS with sustained sorption rates and capacities, whereas PPAC was largely exhausted. As a new type of sorbent for POPs, MPPAC-TEPS has operational advantages, such as magnetic separation and stable regeneration., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

A novel and economic sequential process consisting of precipitation, adsorption, and oxidation was developed to remediate actual rare-earth (RE) wastewater containing various toxic pollutants, including radioactive species. In the precipitation step, porous air stones (PAS) containing waste oyster shell (WOS), PASWOS, was prepared and used to precipitate most heavy metals with >97% removal efficiencies. The SEM-EDS analysis revealed that PAS plays a key role in preventing the surface coating of precipitants on the surface of WOS and in releasing the dissolved species of WOS successively. For the adsorption step, a polyurethane (PU) impregnated by coal mine drainage sludge (CMDS), PUCMDS, was synthesized and applied to deplete fluoride (F), arsenic (As), uranium (U), and thorium (Th) that remained after precipitation. The continuous-mode sequential process using PAS(WOS), PU(CMDS), and ozone (O3) had 99.9-100% removal efficiencies of heavy metals, 99.3-99.9% of F and As, 95.8-99.4% of U and Th, and 92.4% of COD(Cr) for 100 days. The sequential process can treat RE wastewater economically and effectively without stirred-tank reactors, pH controller, continuous injection of chemicals, and significant sludge generation, as well as the quality of the outlet met the EPA recommended limits., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Polystyrene (PS) is made flame retardant by combining with hexabromocyclododecane (HBCD). HBCD can release from consumer products during their production, use or disposal. As a result, it has become a ubiquitous contaminant in the environment with a high potential for bioaccumulation. Therefore, to evaluate the extent of exposure to HBCD from PS, we determined the concentration of HBCD in a variety of products (n=34) made from three types of commonly used PS: expanded PS (EPS), extruded PS foam (XPS), and extruded PS. The concentration of HBCD was highest in EPS, with a mean value and range of 475643±16710ngg(-1) and 106-960000ngg(-1), respectively. PS related to building construction and laboratory uses had a significantly higher concentration of HBCD (3300-905000ngg(-1)), except XPS styroboard (191±100ngg(-1)). Lower concentrations were measured in most food-related products (24.3-199ngg(-1)). However, a relatively high concentration of HBCD was detected in an ice box (960000±29000ngg(-1)), aquaculture buoy (53500±2100ngg(-1)), and disposable tray (8430±730ngg(-1)) used in fish market, raising concern for public health. Our data demonstrate a wide variation in the concentration of HBCD, suggesting a lack of proper controls for the addition of HBCD to PS products. Other brominated flame retardants (BFRs) were also detected in a majority of the XPS products (TBBPA=3.83-545ngg(-1), BTBPE=44-216ngg(-1) and DBDPE=215-4200ngg(-1)). Thus, HBCD is being added to PS along with other BFRs that cannot be ignored., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

In this study, the photocatalytic ozonation process using either UV lamps with a wavelength close to a solar wavelength (UVsolar) or natural solar light was established to study the effects of the major operating parameters on the removal of a toxic disinfection by-product (DBP), dichloroacetonitrile (DCAN), from drinking water. Based on the test results of a bench system, the UVsolar/TiO2/O3 process had the highest DCAN-removal rate among the advanced oxidation processes (AOPs). The optimal TiO2 and ozone doses were 1gL(-1) and 1.13gL(-1)h(-1), respectively, while room temperature (20°C) produced the highest rate constant in the kinetic tests. The kinetic rate constants linearly increased when the UVsolar intensity increased in the range 4.6-25Wm(-2); however, it increased less at intensities higher than 25Wm(-2). The test results of the outdoor system showed that the solar/TiO2/O3 process provided complete removal of DCAN that was two times faster and had about 4.6 times higher energy efficiency than with solar/TiO2. As a green oxidation technique, solar photocatalytic ozonation could be a good alternative for treating recalcitrant and toxic organic pollutants, because it has high oxidation potential and low energy consumption compared to conventional AOPs., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Sequential washing techniques using single or dual agents [sodium hydroxide (NaOH) and hydrochloric acid (HCl) solutions] were applied to arsenic-contaminated soils in an abandoned iron-ore mine area. We investigated the best remediation strategies to maximize arsenic removal efficiency for both soils and arsenic-containing washing solution through conducting a series of batch experiments. Based on the results of a sequential extraction procedure, most arsenic prevails in Fe-As precipitates or coprecipitates, and iron exists mostly in the crystalline forms of iron oxide. Soil washing by use of a single agent was not effective in remediating arsenic-contaminated soils because arsenic extractions determined by the Korean standard test (KST) methods for washed soils were not lower than 6mg kg(-1) in all experimental conditions. The results of X-ray diffraction (XRD) indicated that iron-ore fines produced mobile colloids through coagulation and flocculation in water contacting the soils, containing dissolved arsenic and fine particles of ferric arsenate-coprecipitated silicate. The first washing step using 0.2M HCl was mostly effective in increasing the cationic hydrolysis of amorphous ferrihydrite, inducing high removal of arsenic. Thus, the removal step of arsenic-containing flocs can lower arsenic extractions (KST methods) of washed soils. Among several washing trials, alternative sequential washing using 0.2M HCl followed by 1M HCl (second step) and 1M NaOH solution (third step) showed reliable and lower values of arsenic extractions (KST methods) of washed soils. This washing method can satisfy the arsenic regulation of washed soil for reuse or safe disposal application. The kinetic data of washing tests revealed that dissolved arsenic was easily readsorbed into remaining soils at a low pH. This result might have occurred due to dominant species of positively charged crystalline iron oxides characterized through the sequential extraction procedure. However, alkaline extraction using NaOH was effective in removing arsenic readsorbed onto the surface of crystalline minerals. This is because of the ligand displacement reaction of hydroxyl ions with arsenic species and high pH conditions that can prevent readsorption of arsenic.

Laboratory experiments were conducted to determine the distribution of various arsenic species in tailings and soils. Other specific goal of the tests were to evaluate the extraction efficiency of arsenic using alkaline or acid washing, to determine optimum operational parameters of alkaline washing, and to evaluate the arsenic precipitation of washing effluents by pH adjustment or ferric chloride addition. Alkaline washing using sodium hydroxide was found to be favorable in removing arsenic from tailings or soils having a higher portion of arsenic in the operationally defined crystalline mineral fraction of crystalline oxide and amorphous aluminosilicates. This is due to the ligand displacement reaction of hydroxyl ions with arsenic species and high pH conditions that can prevent readsorption of arsenic because predominant negatively charged crystalline oxides do not attract the negatively charged oxyanions. For tailings, sodium hydroxide had 10-20 times higher extraction efficiencies than hydrochloric- or citric acid. The optimum concentration of sodium hydroxide for soil washing was determined to be 200 mM for all samples, while the optimum ratios were 10:1 and 5:1 for tailings and field/river sedimentary soils, respectively. The washing effluent of river soil was effectively treated by adjusting pH to 5-6 with hydrochloric acid, resulting in arsenic concentrations of <50 microgl(-1). In the case of field soil effluent, an addition of ferric chloride with a minimum mass ratio of 11 (Fe/As) was needed to reduce the arsenic below 50 microgl(-1).