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Sodium alginate (SA) emerges as a promising adsorbent for the remediation of heavy metal-polluted wastewater. However, the systematic investigations on how and the extent to which the various compositions in real water matrices impact its performance were essential but rare when considering its use. Here, we explored the effect of common environmental factors on Cu(II) adsorption by an as-synthesized SA-based hydrogel (SAH). The result showed that high concentration of organics (above 10 mg L-1) had a negative influence on heavy metal removal (decreased by 9.45 % at least), while inorganic ion, turbidity and antibiotics at relatively low concentrations exhibited a negligible even promoting effect (increased by 9.8 % with the presence of 5 mg L-1 Nor). Based on above results and corresponding mechanism analyses, the possible applicable and unsuitable scenarios of SAH can be predicted. SAH could be a great candidate for treating heavy metal-polluted water such as river and lake water, while it is not a good option for electroplating or livestock wastewater which contains high concentration of organic matters. Besides, the operating conditions including pH (5.0 for Cu(II), 6.0 for Ni(II)), contact time (24 h), temperature (298 K) et al. were also determined. Overall, this work provides theoretical guidance and operational strategies for promoting the practical application of SA adsorbent in water treatment.

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Most adsorbents are currently restricted by their single function in pollutant removal from complex wastewater. Herein, we constructed a versatile chitosan-based adsorbent (MC-DA) by grafting amphoteric copolymers with high pH-responsiveness property, aiming at the removal of multiple ionic contaminants. Specifically, the surface charge and hydrophobicity/hydrophilicity of MC-DA can be finely tuned under different pH conditions. As a result, the effective adsorption of cationic methylene blue (MB) and anionic Acid Orange 7 (AO7) with capacities of 627.4 mg/g and 1146.8 mg/g were achieved respectively, superior to most reported materials. Regarding the characterization results, the adsorption mechanisms for MB adsorption were electrostatic and hydrophobic interactions, while the electrostatic attraction was the main driving force for AO7 adsorption. Apart from the versatile adsorption performance, high acid resistance (pH ≥ 2.0), good reusability and rapid separation property under an external magnetic field suggested MC-DA's promising environmental benefits and practical application potential in water remediation.

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Environmental regulation promotes industrial structure change and regional economic transformation through land use adjustment, which gets a new way to explore the path of reforming traditional industrialization and urbanization. Based on the panel data of 128 prefecture-level cities in China 's Yangtze River Economic Belt from 2000 to 2020, this paper uses the spatial Dubin model to analyze the impact of environmental regulation and land use efficiency on the upgrading of industrial structure, and sets the panel threshold model to examine the impact of environmental regulation on the upgrading of industrial structure by affecting land use efficiency. The results show that formal environmental regulation has a significant positive spatial effect on the rationalization and upgrading of industrial structure, which are 0.1734 and 0.2854 respectively. Informal environmental regulation has a negative spillover effect on neighboring provinces but not significant. Heterogeneous environmental regulation has obvious "double threshold effect" on industrial upgrading by affecting land use efficiency. When the threshold of environmental regulation intensity is 0.0315-0.0886, environmental regulation still inhibits land use efficiency and industrial structure upgrading. When the threshold value is greater than 0.0886, environmental regulation has a positive impact on land use efficiency but not significant. With the intensity of environmental regulation from weak to strong, it will produce a double threshold effect of "strong inhibition-weak inhibition-interaction promotion" on the upgrading of manufacturing structure through the adjustment of land use efficiency.

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Metal-organic frameworks (MOFs) have shown great prospects in wastewater remediation. However, the easy aggregation, difficult separation and inferior reusability greatly limit their large-scale application. Herein, we proposed a facile, green and low-cost strategy to construct robust and stable MOF-based hydrogel beads (Fe-BTC-HBs) in a gram scale, and employed them to remove antibiotics from wastewater. As a result, the Fe-BTC-HBs demonstrated outstanding adsorption capacity for both ofloxacin (OFL) and tetracycline (TC) (281.17 mg/g for OFL and 223.60 mg/g for TC) under a near-neutral environment. The main adsorption mechanisms of OFL and TC were hydrogen bonding and π-π stacking interaction. Owing to its macroscopic granule and stable structure, Fe-BTC-HBs can be separated rapidly from wastewater after capturing antibiotics, and more than 85% adsorption capacity still remained after six cycles, while the powdered Fe-BTC only showed less than 6% recovery efficiency with massive weight loss (around 92%). In real industrial effluent, the adsorption performance of Fe-BTC-HBs toward two antibiotics exhibited negligible decreases (2.9% for OFL and 2.2% for TC) compared with that in corresponding solutions. Furthermore, Fe-BTC-HBs also had appealing economic and environmental benefit. Overall, the macro-manufactured MOF beads have the promising potential for the large-scale wastewater treatment.

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In this study, a 3D thornball-like hierarchical ß-In2S3, displaying extremely rapid photodegradation of cationic dyes, was synthesized by a facile method. The formation of a uniform thornball-like structure depended on the microwave reaction method and citric acid as the pH regulator. The size of In2S3 was easily adjusted by changing the microwave irradiation time from 5 min to 15 min. The morphology, structure, composition, energy level, charge separation, and surface properties of different-sized In2S3 were characterized. The results showed that In2S3 synthesized in 10 min (In2S3-10) displayed optimal interface property for the electron-hole separation, maximum hydrophilia with most surface negative charges for the surface adsorption, contributing to the complete photodegradation of rhodamine B (RhB) in just 25 minutes of visible light illumination. The photodegradation path of RhB was speculated with four possible paths, including the processes of de-ethylation, open-ring of xanthene, and rupture of carbon-carbon bonds up to the decomposition into small molecules. Finally, the reusability of In2S3-10 was tested, obtaining nearly 96% photodegradation efficiency after sequential 5 cycles.

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Here we unveiled a novel magnetically separable amphoteric biosorbent (PD-Fe3O4@CCS) and investigated its adsorption behavior toward two classes of heavy metals, hexavalent chromium (Cr(VI)) and copper (Cu(II)) ions from water. Results indicated that the adsorption behavior of PD-Fe3O4@CCS for Cr(VI) was well described by Langmuir model; while for Cu(II) adsorption, the Freundlich model was the better one. Based on the kinetic results, both Cr(VI) and Cu(II) adsorption on PD-Fe3O4@CCS fitted well with the pseudo-second-order kinetic model. To evaluate the reusability and stability of PD-Fe3O4@CCS, regeneration tests were carried out for five cycles. Furthermore, the applicable feasibility of PD-Fe3O4@CCS in the real water matrix (including the single and binary pollutant systems) was studied, and results suggested the promising potential of PD-Fe3O4@CCS for large-scale application. Apart from these, the surface interactions between PD-Fe3O4@CCS and heavy metal ions in single and binary systems were systematically investigated based on FTIR and XPS analyses, which provided an essential implication for comprehending the interactions between biosorbents and contaminants in wastewater.

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Magnetic biosorbents with specific morphological and molecular structure (PMCCs) were designed for the removal of ciprofloxacin (CIP) from water. Radical polymerization method was applied to immobilize the designed polymer brushes onto core-shell shaped magnetic microspheres to fabricate PMCCs. PMCCs exhibited a maximum adsorption capacity of 527.93 mg·g-1, which is much higher than reported adsorbents, owing to the complete stretch of polymer brushes and increased active sites as well as enhanced interaction. The investigation on the adsorption behavior of PMCCs for CIP manifested that CIP adsorption well fitted the Langmuir isotherm model and pseudo-second-order kinetic model. The calculated thermodynamic parameters suggested that CIP adsorption onto PMCCs was spontaneous and exothermic. Further recycling experiments showed a loss of less than 20% in the CIP adsorption capacity after five times, demonstrating the reusability of the as-designed biosorbents.

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Poly(4-vinyl pyridine) decorated magnetic chitosan biopolymer (VMCP), as an absorbent and reductant, was prepared and used to remove hexavalent chromium (Cr(VI)) from aqueous solution. Compared with undecorated magnetic biopolymer, VMCP exhibited significantly improved removal performance under identical experimental conditions. The kinetics, isotherms, and thermodynamics of Cr(VI) adsorption onto VMCP were investigated. Results demonstrated that the maximum monolayer adsorption capacity of VMCP was 344.83 mg/g, which was considerably higher than most reported adsorbents. The mechanism for Cr(VI) removal was explored based on XPS and FTIR analyses. The main mechanisms were concluded to be Cr(VI) adsorption onto the positively charged VMCP surface and the reduction of Cr(VI) to Cr(III), followed by coordination between Cr(III) and N atoms. The easy regeneration, satisfactory reusability, and remarkable performance in column tests revealed the high potential of VMCP in treating Cr(VI)-contaminated water.

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The emissions of brominated flame retardants (BFRs) from consumer products have been considered the major to the ubiquitous occurrence of contaminants in indoor environments. Direct contact with dust covering the surface of source materials in a real environment could introduce significant uncertainty. This study investigated the effects of dust coverage on the emissions of four BFRs, including 1, 2, 5, 6, 9, and 10-hexabromocyclododecane (HBCD), bis(2-ethyl-1-hexyl) tetrabromophthalate (BEHTBP), tetrabromobisphenol A (TBBPA), and hexabromobenzene (HBBZ), from decorative laminate, cotton sound insulation, PVC floor, and carpet. Direct contact with dust was confirmed to increase the total emissions by 30.8-98.1% compared with the emissions in the non-dust group. The emissions of HBCD, TBBPA, and HBBZ from cotton sound insulation were obviously enhanced by dust with smaller particles but did not linearly increase along with the dust amounts. Thus, these findings have practical implications in that the frequent removal of dust could be important to minimize the exposure risk from indoor emissions of BFRs.

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In attempts to evaluate the environmental risk produced by plastic markets, the levels and congener profiles of phthalate esters (PAEs) in soil, vegetable, and sediment samples collected from the plastic market in China, where numerous plastic products are exchanged every year, were investigated. The concentrations of ∑22PAEs ranged from 2131 to 27,805 ng g-1 in agricultural soils, from 8023 to 37,556 ng g-1 in vegetables and from 9031 to 87,329 ng g-1 in sediments. The predominant PAE pollutants were di-(2-ethylhexyl) phthalate (DEHP), di-n-butyl phthalate (DnBP), di-isobutyl phthalate (DiBP), and dibenzyl phthalate (DBzP). The mean percentages of the predominant PAEs in the soil, vegetable, and sediment samples accounted for 98.4%, 97.3%, and 99.5% of the total PAEs, respectively. The concentrations of PAEs at the sites around the plastic market were significantly higher than those at other pollution sites, such as sites contaminated by agricultural plastic film, electronic waste (e-waste) recycling sites, and industrial parks, indicating that the plastic market was an important pollution source. The DEHP concentrations in the soils, vegetables, and sediments and the DnBP concentrations in the vegetables all exceeded the environmental risk levels (ERL) or the environmental allowable levels (EAL), indicating that the plastic market posed potential environmental risks.

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In this study, modified magnetic chitosan microparticles (MCDs) were fabricated and used as adsorbents for the removal of Food Yellow 3 (FY3) and Acid Yellow 23 (AY23) from aqueous solution. The magnetic microparticles were characterized by scanning electronic microscope, Brunauer-Emmett-Teller specific surface area, elemental analysis, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, thermogravimetry analysis, differential scanning calorimetry, and vibrating-sample magnetometer. Then, the effects of pH value, initial dye concentration, and contact time on the adsorption of FY3 and AY23 by MCDs were investigated. Evidently, MCDs showed excellent adsorption performance for both food dyes, and their adsorption capacities (833.33 mg/g for FY3 and 666.67 mg/g for AY23) were considerably higher than those of unmodified adsorbents, which could be attributed to the electrostatic interaction and ion exchange between the grafted cationic polymer and food dyes. Adsorption isotherm and kinetic data of the magnetic microparticles were well fitted by Langmuir isotherm and pseudo-second-order kinetic model, respectively. The regeneration and reusability of MCDs were also explored. Results showed that more than 80% adsorption capacities of MCDs for FY3 and AY23 remained after five adsorption-desorption cycles.

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Novel adsorbents, poly([2-(methacryloxy)ethyl]trimethylammonium chloride) modified magnetic chitosan particles (DMCPs), were synthesized via free radical polymerization and applied to adsorb Cr(VI) from aqueous solution. The effects of pH (2-11), Cr(VI) concentration (10-200 mg/L) and contact time (0-420 min) on the adsorption performance were evaluated. The results showed that the adsorption capacity of DMCPs was much larger than that of magnetic chitosan particles (MCPs) in the examined pH range and decreased with Cl- concentration increasing, indicating that electrostatic interaction and ion exchange are the governing mechanisms of Cr(VI) adsorption by DMCPs. The Langmuir isotherm model and pseudo-second-order kinetic model fitted the experimental data well. The maximum adsorption capacity of DMCPs is 153.85 mg/g. Besides, Cr(VI)-loaded DMCPs could be easily separated and efficiently regenerated. Therefore, DMCPs are promising candidates for Cr(VI) adsorption owing to their excellent performance in a wide pH range, easy separation and good reusability.

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