Adsorption of typical NDMA precursors by superfine powdered activated carbon: Critical role of particle size reduction.

Control of N-nitrosodimethylamine (NDMA) in drinking water could be achieved by removing its precursors as one practical way. Herein, superfine powdered activated carbons with a diameter of about 1 µm (SPACs) were successfully prepared by grinding powdered activated carbon (PAC, D50=24.3 µm) and applied to remove model NDMA precursors, i.e. ranitidine (RAN) and nizatidine (NIZ). Results from grain diameter experiments demonstrated that the absorption velocity increased dramatically with decreasing particle size, and the maximum increase in k2 was 26.8-folds for RAN and 33.4-folds for NIZ. Moreover, kinetic experiments explained that rapid absorption could be attributed to the acceleration of intraparticle diffusion due to the shortening of the diffusion path. Furthermore, performance comparison experiments suggested that the removal of RAN and NIZ (C0=0.5 mg/L) could reach 61.3% and 60%, respectively, within 5 min, when the dosage of SAPC-1.1 (D50=1.1 µm) was merely 5 mg/L, while PAC-24.3 could only eliminate 17.5% and 18.6%. The adsorption isotherm was well defined by Langmuir isotherm model, indicating that the adsorption of RAN/NIZ was a monolayer coverage process. The adsorption of RAN or NIZ by SAPC-1.1 and PAC-24.3 was strongly pH dependent, and high adsorption capacity could be observed under the condition of pH > pka+1. The coexistence of humic acid (HA) had no significant effect on the adsorption performance because RAN/NIZ may be coupled with HA and removed simultaneously. The coexistence of anions had little effect on the adsorption also. This study is expected to provide an alternative strategy for drinking water safety triggered by NDMA.

Microplastics enhance the adsorption capacity of zinc oxide nanoparticles: Interactive mechanisms and influence factors.

Microplastics (MPs) are of particular concern due to their ubiquitous occurrence and propensity to interact and concentrate various waterborne contaminants from aqueous surroundings. Studies on the interaction and joint toxicity of MPs on engineered nanoparticles (ENPs) are exhaustive, but limited research on the effect of MPs on the properties of ENPs in multi-solute systems. Here, the effect of MPs on adsorption ability of ENPs to antibiotics was investigated for the first time. The results demonstrated that MPs enhanced the adsorption affinity of ENPs to antibiotics and MPs before and after aging showed different effects on ENPs. Aged polyamide prevented aggregation of ZnONPs by introducing negative charges, whereas virgin polyamide affected ZnONPs with the help of electrostatic attraction. FT-IR and XPS analyses were used to probe the physicochemical interactions between ENPs and MPs. The results showed no chemical interaction and electrostatic interaction was the dominant force between them. Furthermore, the adsorption rate of antibiotics positively correlated with pH and humic acid but exhibited a negative correlation with ionic strength. Our study highlights that ENPs are highly capable of accumulating and transporting antibiotics in the presence of MPs, which could result in a widespread distribution of antibiotics and an expansion of their environmental risks and toxic effects on biota. It also improves our understanding of the mutual interaction of various co-existing contaminants in aqueous environments.

Efficient magnetic capture of PE microplastic from water by PEG modified Fe3O4 nanoparticles: Performance, kinetics, isotherms and influence factors.

Due to their resistance to degradation, wide distribution, easy diffusion and potential uptake by organisms, microplastics (MPs) pollution has become a major environmental concern. In this study, PEG-modified Fe3O4 magnetic nanoparticles demonstrated superior adsorption efficiency against polyethylene (PE) microspheres compared to other adsorbents (bare Fe3O4, PEI/Fe3O4 and CA/Fe3O4). The maximum adsorption capacity of PE was found to be 2203 mg/g by adsorption isotherm analysis. PEG/Fe3O4 maintained a high adsorption capacity even at low temperature (5°C, 2163 mg/g), while neutral pH was favorable for MP adsorption. The presence of anions (Cl-, SO42-, HCO3-, NO3-) and of humic acids inhibited the adsorption of MPs. It is proposed that the adsorption process was mainly driven by intermolecular hydrogen bonding. Overall, the study demonstrated that PEG/Fe3O4 can potentially be used as an efficient control against MPs, thus improving the quality of the aquatic environment and of our water resources.

Investigation on cost-effective composites for CO2 adsorption from post-gasification residue and metal organic framework.

Cost-effective CO2 adsorbents are gaining increasing attention as viable solutions for mitigating climate change. In this study, composites were synthesized by electrochemically combining the post-gasification residue of Macadamia nut shell with copper benzene-1,3,5-tricarboxylate (CuBTC). Among the different composites synthesized, the ratio of 1:1 between biochar and CuBTC (B 1:1) demonstrated the highest CO2 adsorption capacity. Under controlled laboratory conditions (0°C, 1 bar, without the influence of ambient moisture or CO2 diffusion limitations), B 1:1 achieved a CO2 adsorption capacity of 9.8 mmol/g, while under industrial-like conditions (25°C, 1 bar, taking into account the impact of ambient moisture and CO2 diffusion limitations within a bed of adsorbent), it reached 6.2 mmol/g. These values surpassed those reported for various advanced CO2 adsorbents investigated in previous studies. The superior performance of the B 1:1 composite can be attributed to the optimization of the number of active sites, porosity, and the preservation of the full physical and chemical surface properties of both parent materials. Furthermore, the composite exhibited a notable CO2/N2 selectivity and improved stability under moisture conditions. These favorable characteristics make B 1:1 a promising candidate for industrial applications.

Enhancing the photocatalytic efficiency by the molecular modification effect derived from pollutant adsorption on highly crystalline BiOBr.

The adsorption of pollutants can not only promote the direct surface reaction, but also modify the catalyst itself to improve its photoelectric characteristics, which is rarely studied for water treatment with inorganic photocatalyst. A highly crystalline BiOBr (c-BiOBr) was synthesized by a two-step preparation process. Owing to the calcination, the highly crystalline enhanced the interface interaction between pollutant and c-BiOBr. The complex of organic pollutant and [Bi2O2]2+ could promote the active electron transfer from the adsorbed pollutant to c-BiOBr for the direct pollutant degradation by holes (h+). Moreover, the pollutant adsorption actually modified c-BiOBr and promoted more unpaired electrons, which would coupling with the photoexcitation to promote generate more O2•-. The molecular modification effect derived from pollutant adsorption significantly improved the removal of pollutants. This work strongly deepens the understanding of the molecular modification effect from the pollutant adsorption and develops a novel and efficient approach for water treatment.

The effect of adsorbent textural and functional properties on model naphthenic acid adsorption.

Naphthenic acids, NAs, are a major contaminant of concern and a focus of much research around remediation of oil sand process affected waters, OSPW. Using activated carbon adsorbents are an attractive option given their low cost of fabrication and implementation. A deeper evaluation of the effect NA structural differences have on uptake affinity is warranted. Here we provide an in-depth exploration of NA adsorption including many more model NA species than have been assessed previously with evaluation of adsorption kinetics and isotherms at the relevant alkaline pH of OSPW using several different carbon adsorbents with pH buffering to simulate the behaviour of real OSPW. Uptake for the NA varied considerably regardless of the activated carbon used, ranging from 350 mg/g to near zero highlighting recalcitrant NAs. The equilibrium data was explored to identify structural features of these species and key physiochemical properties that influence adsorption. We found that certain NA will be resistant to adsorption when hydrophobic adsorbents are used. Adsorption isotherm modelling helped explore interactions occurring at the interface between NA and adsorbent surfaces. We identified the importance of NA hydrophobicity for activated carbon uptake. Evidence is also presented that indicates favorable hydrogen bonding between certain NA and surface site hydroxyl groups, demonstrating the importance of adsorbent surface functionality for NA uptake. This research highlights the challenges associated with removing NAs from OSPW through adsorption and also identifies how adsorbent surface chemistry modification can be used to increase the removal efficiency of recalcitrant NA species.

Synergistic effect of silicon availability and salinity on metal adsorption in a common estuarine diatom.

Increasing nitrogen and phosphorus discharge and decreasing sediment input have made silicon (Si) a limiting element for diatoms in estuaries. Disturbances in nutrient structure and salinity fluctuation can greatly affect metal uptake by estuarine diatoms. However, the combined effects of Si and salinity on metal accumulation in these diatoms have not been evaluated. In this study, we aimed to investigate how salinity and Si availability combine to influence the adsorption of metals by a widely distributed diatom Phaeodactylum tricornutum. Our data indicate that replete Si and low salinity in seawater can enhance cadmium and copper adsorption onto the diatom surface. At the single-cell level, surface potential was a dominant factor determining metal adsorption, while surface roughness also contributed to the higher metal loading capacity at lower salinities. Using a combination of non-invasive micro-test technology, atomic force microscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy, we demonstrate that the diversity and abundance of the functional groups embedded in diatom cell walls vary with salinity and Si supply. This results in a change in the cell surface potential and transient metal influx. Our study provides novel mechanisms to explain the highly variable metal adsorption capacity of a model estuarine diatom.

Cu/TiO2 adsorbents modified by air plasma for adsorption-oxidation of H2S.

In this study, non-thermal plasma (NTP) was employed to modify the Cu/TiO2 adsorbent to efficiently purify H2S in low-temperature and micro-oxygen environments. The effects of Cu loading amounts and atmospheres of NTP treatment on the adsorption-oxidation performance of the adsorbents were investigated. The NTP modification successfully boosted the H2S removal capacity to varying degrees, and the optimized adsorbent treated by air plasma (Cu/TiO2-Air) attained the best H2S breakthrough capacity of 113.29 mg H2S/gadsorbent, which was almost 5 times higher than that of the adsorbent without NTP modification. Further studies demonstrated that the superior performance of Cu/TiO2-Air was attributed to increased mesoporous volume, more exposure of active sites (CuO) and functional groups (amino groups and hydroxyl groups), enhanced Ti-O-Cu interaction, and the favorable ratio of active oxygen species. Additionally, the X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) results indicated the main reason for the deactivation was the consumption of the active components (CuO) and the agglomeration of reaction products (CuS and SO42-) occupying the active sites on the surface and the inner pores of the adsorbents.

A new insight into the straw decomposition associated with minerals: Promoting straw humification and Cd immobilization.

Organic matter (OM) derived from the decomposition of crop residues plays a key role as a sorbent for cadmium (Cd) immobilization. Few studies have explored the straw decomposition processes with the presence of minerals, and the effect of newly generated organo-mineral complexes on heavy metal adsorption. In this study, we investigated the variations in structure and composition during the rice straw decomposition with or without minerals (goethite and kaolinite), as well as the adsorption behavior and mechanisms by which straw decomposition affects Cd immobilization. The degree of humification of extracted straw organic matter was assessed using excitation-emission matrix (EEM) fluorescence and Ultraviolet-visible spectroscopy (UV-vis), while employing FTIR spectroscopy and XPS to characterize the adsorption mechanisms. The spectra analysis revealed the enrichment of highly aromatic and hydrophobic components, indicating that the degree of straw decomposition and humification were further intensified during incubation. Additionally, the existence of goethite (SG) accelerated the humification of OM. Sorption experiments revealed that the straw humification increased Cd adsorption capacity. Notably, SG exhibited significantly higher adsorption performance compared to the organic matter without minerals (RS) and the existence of kaolinite (SK). Further analysis using FT-IR spectroscopy and XPS verified that the primary mechanisms involved in Cd immobilization were complexion with -OH and -COOH, as well as the formation of Cd-π binds with aromatic C=C on the surface of solid OMs. These findings will facilitate understanding the interactions of the rice straw decomposing with soil minerals and its remediation effect on Cd-contaminated farmland.

Spatial confinement: An effective strategy to improve H2O and SO2 resistance of the expandable graphite-modified TiO2-supported Pt nanocatalysts for CO oxidation.

The expandable graphite (EG) modified TiO2 nanocomposites were prepared by the high shear method using the TiO2 nanoparticles (NPs) and EG as precursors, in which the amount of EG doped in TiO2 was 10 wt.%. Followed by the impregnation method, adjusting the pH of the solution to 10, and using the electrostatic adsorption to achieve spatial confinement, the Pt elements were mainly distributed on the exposed TiO2, thus generating the Pt/10EG-TiO2-10 catalyst. The best CO oxidation activity with the excellent resistance to H2O and SO2 was obtained over the Pt/10EG-TiO2-10 catalyst: CO conversion after 36 hr of the reaction was ca. 85% under the harsh condition of 10 vol.% H2O and 100 ppm SO2 at a high gaseous hourly space velocity (GHSV) of 400,000 hr-1. Physicochemical properties of the catalysts were characterized by various techniques. The results showed that the electrostatic adsorption, which riveted the Pt elements mainly on the exposed TiO2 of the support surface, reduced the dispersion of Pt NPs on EG and achieved the effective dispersion of Pt NPs, hence significantly improving CO oxidation activity over the Pt/10EG-TiO2-10 catalyst. The 10 wt.% EG doped in TiO2 caused the TiO2 support to form a more hydrophobic surface, which reduced the adsorption of H2O and SO2 on the catalyst, greatly inhibited deposition of the TiOSO4 and formation of the PtSO4 species as well as suppressed the oxidation of SO2, thus resulting in an improvement in the resistance to H2O and SO2 of the Pt/10EG-TiO2-10 catalyst.

Morphologically controlled synthesis of MgFe-LDH using MgO and succinic acid for enhanced arsenic adsorption: Kinetics, equilibrium, and mechanism studies.

In this study, we investigated improving the performance of a layered double hydroxide (LDH) for the adsorption of As(III) and As(V) by controlling the morphology of LDH crystals. The LDH was synthesized via a simple coprecipitation method using barely soluble MgO as a precursor and succinic acid (SA) as a morphological control agent. Doping the LDH crystals with carboxylate ions (RCOO-) derived from SA caused the crystals to develop in a radial direction. This changed the pore characteristics and increased the density of active surface sites. Subsequently, SA/MgFe-LDH showed excellent affinity for As(III) and As(V) with maximum sorption densities of 2.42 and 1.60 mmol/g, respectively. By comparison, the pristine MgFe-LDH had sorption capacities of 1.56 and 1.31 mmol/g for As(III) and As(V), respectively. The LDH was effective over a wide pH range for As(III) adsorption (pH 3-8.5) and As(V) adsorption (pH 3-6.5). Using a combination of spectroscopy and sorption modeling calculations, the main sorption mechanism of As(III) and As(V) on SA/MgFe-LDH was identified as inner-sphere complexation via ligand exchange with hydroxyl group (-OH) and RCOO-. Specifically, bidentate As-Fe complexes were proposed for both As(III) and As(V) uptake, with the magnitude of formation varying with the initial As concentration. Importantly, the As-laden adsorbent had satisfactory stability in simulated real landfill leachate. These findings demonstrate that SA/MgFe-LDH exhibits considerable potential for remediation of As-contaminated water.

Insight into the mechanism of adsorption and release of 11-nor-9-carboxy-Δ9-tetrahydrocannabinol in sewage by modeling regional suspended particles for evaluation of the influence on monitoring of cannabis illicit abuse.

The adsorption of 11-nor-9-carboxy-∆9-tetrahydrocannabinol (THC-COOH) by the suspended particles in sewage makes it fail to accurately monitor cannabis abuse. In this work, the model sewage sample was prepared through equivalent mixing the sewage from 10 different sewage treatment plants in Guangdong province of China and used as a comprehensive representative for investigating the adsorption and release behavior of THC-COOH on the suspended particles under different temperature and pH. The solid-liquid distribution of THC-COOH in sewage depended strongly on the adsorption and release properties which were susceptible to the temperature and pH, specially adjusting pH to 11.0 could release more than 90 % of THC-COOH from the suspended particles. By means of the kinetics models, pseudo-second-order kinetic and Weber-Morris models revealed the mechanism of adsorption and release of THC-COOH in sewage that was a relatively reversible and controllable process with multiple interactions, and then it was further confirmed by the validation experiment in a variety of actual sewage samples. According to the suggested pH, the modification of the existing detection protocol prior to high performance liquid chromatography-tandem triple quadrupole mass spectrometry (HPLC-TQ-MS/MS), was successfully applied to determination of THC-COOH in the stimulated positive samples, and the recoveries and RSDs were respectively 95.48-99.79 % and 4.0-5.6 %. The finding could greatly help improving the accuracy of not only the detection of THC-COOH in sewage but also the estimation data of the consumption level of cannabis in the related regions.

Optimization of hydrochar synthesis conditions for enhanced Cd(II) and Pb(II) adsorption in mono and multimetallic systems.

The characterisation of hydrochars derived from Sargassum biomass collected along the Mexican Caribbean coast reveals their favourable morphology and chemical composition for incorporating metal ions, including Cd(II) and Pb(II). Among the synthesized materials, HCS-3, produced at 180 °C with a 2 h residence time, exhibited superior yield, specific area, carbon content, and capacity for removing Cd(II) and Pb(II). Adsorption equilibrium studies demonstrate the presence of adsorption processes during Cd(II) and Pb(II) retention on HCS-3, with adsorption capacities slightly exceeding 140 and 340 mg g⁻1, respectively. Notably, HCS-3 shows a greater affinity for Pb(II) over Cd(II) when both elements are present concurrently. The physicochemical analysis through FTIR spectroscopy, functional group analysis, point of zero charge determination, SEM/EDS, and other techniques evidenced that HCS-3 possesses favourable characteristics to serve as a heavy metal adsorbent. These findings underscore the efficacy of hydrochars from Sargassum biomass in removing heavy metals, suggesting their potential as superior adsorbents compared to traditional or novel materials, and advising its possible versatility for other pollutants. Utilizing these hydrochars could mitigate the economic and environmental impact of Sargassum biomass by repurposing it for valuable applications.

Resourceful exploitation of sedimentary clay: Designing a dual-chambered borosilicate glass reactor system for the efficient treatment of malachite green and phenol through SCRT adsorption and 5%Fe@SRCT catalysis via CWPO, with evaluation of seed germination and fish survival.

This study presents an innovative double-walled borosilicate glass reactor system for the efficient treatment of liquid and gaseous wastewater. This reactor system allows precise temperature control, continuous pH monitoring, and controlled dosing of reagents to optimize reaction conditions. Detailed characterization was carried out by X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FTIR), BET (specific surface area) analysis, point of zero charge (PZC), and scanning electron microscopy (SEM) for the SCR, SCRT, and 5%Fe@SCRT materials. For Malachite Green adsorption, SRCT demonstrated a maximum adsorption capacity of 39.78 ± 0.5 mg/g using the Langmuir isotherm model and followed pseudo-second-order kinetics. Optimum conditions for adsorption were found to be: an initial concentration of 50 ppm, an adsorbent dosage of 1 g/l, a pH of 8.5, and a temperature of 50°C. For the catalytic oxidation of phenol, 5%Fe@SRCT achieved a remarkable removal rate of 99.9 ± 0.1% under optimum conditions (50 ppm phenol, 1 g/l catalyst dosage, pH 3.5, H2O2 concentration 8.7 mM, and temperature 70°C). Intermediates identified during the reaction included hydroquinone, benzoquinone, catechol, and resorcinol, with degradation occurring over a 60-minute reaction period. The 5%Fe@SCRT material showed excellent reusability in the removal of phenol by catalytic oxidation, with no significant loss of efficiency over three cycles, while the SRCT underwent three cycles of regeneration for the adsorption of Malachite Green. Scavenger tests confirmed the involvement of hydroxyl radicals in the catalytic oxidation process. In addition, fish survival tests after catalytic oxidation of phenol by 5%Fe@SRCT showed no impact on fish, underlining the environmental safety of this process. In addition, germination tests after decolorization of MG by SRCT demonstrated a good effect with no negative impact, reinforcing the ecological value of this innovative technology. These results highlight the innovative use of SCRT and 5%Fe@SCRT as versatile materials for environmental remediation, exploiting their effective adsorption capacities and efficient catalytic oxidation performance within the proposed double-walled borosilicate glass reactor system. PRACTITIONER POINTS: The study demonstrates the effectiveness of an innovative reactor system employing SRCT adsorbent and Fe@SRCT catalyst for efficient removal of malachite green and phenol from wastewater. Environmental impact assessment, including seed germination and fish survival evaluation, validates the method's eco-friendly potential. Implementation of this approach could significantly contribute to sustainable water treatment practices.

Construction and Biological Evaluation of Different Nanoshell Thickness Ni@SiO2 Nanotubes as Good Protein Separation Carriers for Bovine Hemoglobin.

BACKGROUND: Nickel nanomaterials play an important role in biological applications, but they have high toxicity and poor biocompatibility. To overcome these defects, we coated the surface of Ni nanotubes with different thicknesses of SiO2 to reduce cytotoxicity, improve biocompatibility, and broaden their biological application value. OBJECTIVE: This study aimed to construct Ni nanotubes with different thicknesses of SiO2 nanoshells; investigate the effects of silicon layer thickness, incubation time, and cell line category on the cytotoxicity of the as-synthesized materials, and evaluate the biocompatibility of the materials by biological enzymes. The Ni@SiO2-NH2 was selected for use as an adsorbent for the adsorption and purification of histidine-rich proteins, such as Bovine Hemoglobin (BHb). METHODS: Magnetic Ni nanotubes were prepared by the template-chemical deposition method. A modified version of the Stöber process was used for the SiO2 coating of Ni@SiO2 nanotubes, and adjusted by changing the volume of TEOS for different thicknesses of SiO2 nanoshells. RESULTS: Different cell lines containing tumor cells and normal cells were used in the toxicity experiment, which confirmed the low cytotoxicity and good biocompatibility of Ni@SiO2. To achieve high efficiency of immobilization and purification of histidine- rich proteins, Ni@SiO2-NH2 was obtained by introducing the amino functional group. The Ni@SiO2-NH2 was found to possess lower cytotoxicity and higher adsorption capacity compared to other synthesized materials. Besides, the Ni@SiO2-NH2 also exhibited good selectivity of histidine-rich proteins. CONCLUSION: This work has not only provided ideas for reducing the cytotoxicity and improving the biocompatibility of biological nanomaterials, but also laid a foundation for subsequent biological applications.

Viologen-Derived Covalent Organic Frameworks: Advancing PFAS Removal Technology with High Adsorption Capacity.

The escalating presence of per- and polyfluoroalkyl substances (PFAS) in drinking water poses urgent public health concerns, necessitating effective removal. This study presents a groundbreaking approach, using viologen to synthesize covalent organic framework nanospheres: MELEM-COF and MEL-COF. Characterized by highly crystalline features, these nanospheres exhibit exceptional affinity for diverse anionic PFAS compounds, achieving simultaneous removal of multiple contaminants within 30 min. Investigating six anionic PFAS compounds, MEL- and MELEM-COFs achieved 90.0-99.0% removal efficiency. The integrated analysis unveils the synergistic contributions of COF morphology and functional properties to PFAS adsorption. Notably, MELEM-COF, with cationic surfaces, exploits electrostatic and dipole interactions, with a 2500 mg g-1 adsorption capacity-surpassing all reported COFs to date. MELEM-COF exhibits rapid exchange kinetics, reaching equilibrium within 30 min. These findings deepen the understanding of COF materials and promise avenues for refining COF-based adsorption strategies.

Probiotic bacterial adsorption coupled with CRISPR/Cas12a system for mercury (II) ions detection.

The complex sample matrix poses significant challenges in accurately detecting heavy metals. In view of its superior performance for the biological adsorption of heavy metals, probiotic bacteria can be explored for functional unit to eliminate matrix interference. Herein, Lactobacillus rhamnosus (LGG) demonstrates a remarkable tolerance and can adsorb up to 300 µM of Hg2+, following the Freundlich isotherm model with the correlation coefficient (R2) value of 0.9881. Subsequently, by integrating the CRISPR/Cas12a system, a sensitive and specific fluorescent biosensor, "Cas12a-MB," has been developed for Hg2+ detection. Specifically, Hg2+ adsorbed onto LGG can specifically bind to the nucleic acid probe, thereby inhibiting the binding of the probe to LGG and the subsequent activation of the CRISPR/Cas12a system. Under optimal experimental conditions, with the detection time of 90 min and the detection limit of 0.44 nM, the "Cas12a-MB" biosensor offers a novel, eco-friendly approach for Hg2+ detection, showcasing the innovative application of probiotics in biosensor.

Unraveling the interplay of common groundwater ions in arsenic removal by sulfide-modified nanoscale zerovalent iron.

Sulphidation of nZVI (S-nZVI) has shown to significantly improve the arsenic removal capacity of nZVI, concurrently modifying the sequestration mechanism. However, to better apply S-nZVI for groundwater arsenic remediation, the impact of groundwater coexisting ions on the efficacy of arsenic uptake by S-nZVI needs to be investigated. This present study evaluates the potential of S-nZVI to remove arsenic in the presence of typical groundwater coexisting ions such as Cl-, HA, HCO3-, PO43- and SO42- through batch adsorption experiments. Individually, PO43- and HA had a dominant inhibition effect, while SO42- promoted As(III) removal by S-nZVI. Conversely, for As(V) removal, HCO3- and SO42- impeded the removal process. X-ray spectroscopic investigation suggests that the coexisting ions can either compete with arsenic for the adsorption sites, influence the S-nZVI corrosion rates and/or generate distinct corrosion products, thereby interfering with arsenic removal by S-nZVI. To investigate the cumulative effects of these ions, a 25-1 Fractional Factorial Design of experiments was employed, wherein the concentration of all the ions were varied simultaneously in an optimized manner, and their impact on arsenic removal by S-nZVI was observed. Our results shows that when these ions are present concurrently, PO43-, SO42- and HA still exerted a dominant influence on As(III) removal, whereas HCO3- was the main ions affecting As(V) removal, although the combined influence of the ions was not merely a summation of their individual effects. Overall, the finding of our study might provide valuable insight for predicting the actual performance of S-nZVI in field-scale applications for the remediation of arsenic-contaminated groundwater.

Roto-Cyclization of 4-Bromopicene in On-Surface Synthesis.

Progress toward single-molecule electronics relies on a thorough understanding of the understanding of local physio-chemical processes and development of synthetic routines for controlled heterocoupling. We demonstrate a structurally unexpected ring closure process for a homo-coupled 4,4'-bipicenyl, realized in on-surface synthesis. An initial covalent C-C coupling of 4-bromopicene locks at lower temperatures the position and geometrically shields part of 4,4'-bipicenyl. Employing this effect of shielding might offer a path toward controlled stepwise hetero-coupling. At higher temperatures, a thermally activated three-dimensional rotation upon hydrogen dissociation, a dehydrogenative roto-cyclization, lifts the surface dimensionality restriction, and leads to the formation of a perylene. Thereby, the shielded molecular part becomes accessible again.

Co-regulating the pore structure and surface chemistry of sludge-based biochar for high-performance deodorization of gaseous dimethyl disulfide.

A straightforward and eco-friendly preparation method for porous sludge biochar (SBA-3) was developed to deodorize gaseous dimethyl disulfide (DMDS) using ion exchange to adjust micropore structures coupled with carboxyl functionalization. Compared with the unmodified sludge biochar SBA-1 and SBA-2 treated with ion exchange, the pore size of SBA-3 decreased accompanied with increasing specific surface area and micropore volume. The Brunauer-Emmett-Teller (BET) specific surface area and micropore volume were 176.35 m2 g-1 and 0.0314 cm³ g-1, which were 2.02 and 1.71-fold larger than those of SBA-2, as well as 20.60 and 78.5-fold larger than those of SBA-1, respectively. Meanwhile, the amount of -COOH on the surface of SBA-3 increased from 0.425 to 1.123 mmol g-1, which was 2.64-fold larger than that of SBA-1. The adsorption behavior between DMDS and SBA-3 could be well described by the quasi-second-order kinetic model and Langmuir isotherm model. The maximum monolayer adsorption capacity was 35.12 mg g-1 at 303 K. Thermodynamic and DFT calculations indicated that the adsorption of DMDS on SBA-3 was exothermic with the deodorization mechanisms involving pore filling and chemisorption.