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[Display omitted] The rapid development of process technology has led to rapid daily industrial production, which also produced a large amount of waste liquid. At the same time, the existing treatment technology cannot keep up with the demand, resulting in the malicious destruction of the environment by wastewater, especially mercury-containing wastewater was very harmful. Effective means of removing mercury ions need to be found. With magnetic ferric oxide as the core and titanium-based metal–organic frameworks as the shell, a new type of magnetic adsorbent (BTA-MIL-125(Ti)@Fe 3 O 4) was synthesized. Materials were tested by multiple characterization methods and multiple sets of experiments. At optimal pH 6, the removal rate in 100 ppm Hg(Ⅱ) was as high as 95.8%. The theoretical adsorption capacity was 615 mg/L. Isothermal experiments, kinetic experiments and thermodynamic experiments have respectively verified that the material was a kind of adsorption material with self-emission heat based on chemical action and synergistic adsorption with Hill model. By simulating the immunity of a variety of ions (Cu, Zn, Mg, Ni, Cd), the material itself also exhibited a very high affinity for Hg(Ⅱ). The results of five high-cycle stable adsorption proved the repeatable stability of the material itself. Various characterization methods have also shown that nitrogen and sulfur-containing groups chelated with Hg(Ⅱ). All of the above was enough to show that the BTA-MIL-125(Ti)@Fe 3 O 4 was a magnetic adsorption material with excellent performance and great prospects. [ABSTRACT FROM AUTHOR]

To evaluate the synergetic adsorption capacity of layered double hydroxide (LDH) and photocatalytic reduction property of TiO 2 for aqueous Cr(VI), the Fe 3 O 4 -ZnAl-LDH and TiO 2 composites (FLT) were prepared via sol-gel method. The removal efficiency of FLT composites for Cr(VI) changed with the mass ratio of Fe 3 O 4 -LDH/TiO 2 , and the optimal ratio was 20% (FLT-2). The adsorption efficiencies of 100 mg FLT-2 were 74% and 64% for 20 and 50 mg/L Cr(VI) solution, and the total removal ratios of Cr(VI) were all over 97% after UV irradiation. The experimental data of adsorption kinetic, adsorption isothermal, and photocatalytic reduction were consistent with the pseudo-second-order, Langmuir, and first-order reaction equations, respectively. From the X–ray photoelectron spectra analysis, FLT composites adsorbed Cr(VI) directly via surface complexation, also reduced aqueous Cr(VI) to Cr(III). The photocurrent and electrochemical impedance spectroscopy of FLT composites indicated the photo-induced electron-hole pairs were separated effectively. The regeneration results show that the FLT composites had good stability and reusability after five consecutive cycles. Therefore, FLT composites are promising materials in the disposal of wastewater containing Cr(VI). [ABSTRACT FROM AUTHOR]

In spite of recent progress in developing hollow micro/nanostructures, the synthesis of three-dimensional adsorbents with high adsorption efficiency and capability on the basis of these structures still remains a great challenge. Herein, we demonstrate a facile hydrothermal strategy to synthesize uniformly dispersed hollow CuWO 4 spheres. The as-prepared CuWO 4 spheres with unique mesoporous structure show favorable selective adsorption for cationic dyes and good recyclability. The adsorption capacity of hollow CuWO 4 towards methylene blue (MB) reaches 59.82 mg g −1 . Furthermore, the hollow CuWO 4 spheres present enhanced photoelectrochemical performance under visible light illumination. This strategy of acquiring specifically functionalized materials from smart design and simple chemical process has opened up wide opportunities on the fabrication of alternative absorbents and photoelectrodes based on CuWO 4 substrate. [ABSTRACT FROM AUTHOR]

Microplastics (MPs) are emerging pollutants that act as a carrier of toxic pollutants, release toxic substances, and aggregate in biota. The adsorption behavior of MPs has recently become a research hot spot. The objective of this study was to summarize the main mechanisms by which MPs adsorb organic pollutants, introduce some mathematical models commonly used to study the adsorption behavior of MPs, and discuss the factors affecting the adsorption capacity from three perspectives, i.e., the properties of MPs and organic pollutants, and environmental factors. Adsorption kinetics and isothermal adsorption models are commonly used to study the adsorption of organic pollutants on MPs. We observed that hydrophobic interaction is the most common mechanism by which MPs adsorb organic pollutants, and also reportedly controls the portion of organic pollutants. Additionally, electrostatic interaction and other non-covalent forces, such as hydrogen bonds, halogen bonds, and π–π interactions, are also mechanisms of organic pollutant adsorption on MPs. The particle size, specific surface area, aging degree, crystallinity, and polarity of MPs, and organic pollutant properties (hydrophobicity and dissociated forms) are key factors affecting adsorption capacity. Changes in the pH, temperature, and ionic strength also affect the adsorption capacity. Current research on the adsorption behavior of MPs has mainly been conducted in laboratories, and in-depth studies on the adsorption mechanism and influencing factors are limited. Therefore, studies on the adsorption behavior of MPs in the environment are required, and this study will contribute to a better understanding of this topic. [Display omitted] • This study reviews the mechanisms by which microplastics adsorb organic pollutants. • Factors affecting the adsorption capacity of microplastics are determined. • Microplastics adsorb organic pollutants mainly through hydrophobic interactions. • Microplastic and environmental properties affect adsorption of organic pollutants. [ABSTRACT FROM AUTHOR]

[Display omitted] • CAL and PPy-CAL were prepared using hydrothermal and in situ polymerization methods. • The theoretical adsorption capacity of CAL-PPy for Cr(VI) was nearly twice than that of CAL. • CAL-PPy removed 100 mg/L of aqueous Cr(VI) efficiently and quickly. • Mechanisms included electrostatic attraction, anion exchange, complexation, and reduction. To efficiently remove high concentrations of hexavalent chromium (Cr(VI)), calcium–aluminum-layered double hydroxide (CaAl-LDH, denoted as CAL), and polypyrrole-modified CAL (CAL-PPy) were prepared by hydrothermal and in situ polymerization methods, respectively. The chemical structure, morphology, and elemental results indicated that the chain-like polypyrrole was decorated with hexagonal CAL. The specific surface area of CAL-PPy increased from 8.746 m2/g to 24.24 m2/g. The adsorption performances of CAL and CAL-PPy for aqueous Cr(VI) were investigated using batch equilibrium experiments. The decontamination process of aqueous Cr(VI) (100 mg/L) reached the equilibrium state within 50 min, and the kinetic data met the pseudo-second-order kinetic equation. The Langmuir model described the isothermal data properly, and the obtained theoretical adsorption capacity of CAL for Cr(VI) at 318 K was 34.06 mg/g, while that of CAL-PPy was 66.14 mg/g. The removal mechanisms involved electrostatic attraction, surface complexation, anion exchange, and reduction to low-toxicity Cr(III). Therefore, CAL and CAL-PPy have underlying applications in treating real wastewater containing Cr(VI). [ABSTRACT FROM AUTHOR]

The use of algae to adsorb heavy metals is an efficient and environmentally friendly treatment for contaminated water and has attracted widespread research attention. In this study, a meta-analysis of the heavy metal adsorption capacity of algae from five different phyla and the factors influencing these capacities was conducted. Phaeophyta was found to have a high heavy metal adsorption capacity, whereas Bacillariophyta had a relatively low adsorption capacity; Chlorophyta, Rhodophyta, and Cyanophyta had moderate adsorption capacities. Non-living algae were more effective in practical applications than living algae were. Algal biomass had a relatively high adsorption efficiency of 1–10 g/L, which did not increase significantly when algal concentration increased. The algal adsorption efficiency for initial heavy metal concentrations of 10–100 mg/L was higher than for concentrations of greater than 100 mg/L. The results further show that algal adsorption of heavy metals reached a maximum capacity of 80–90% within 20 min. Heavy metal adsorption by algae was not temperature-dependent, and it was more effective in moderately to weakly acidic environments (pH = 4–7.5). Considering these aspects for practical applications, algae from some phyla can effectively be used for heavy metal biosorption in contaminated water. • Heavy metal adsorption capacities of algae from five phyla were determined via meta-analysis. • Phaeophyta is the optimal material for removal of heavy metal. • Non-living algae adsorbed heavy metals more effectively than living algae did. • Alkaline environments were not conducive to algal adsorption of heavy metals. • Algae could adsorb most heavy metals over a short period. [ABSTRACT FROM AUTHOR]

The “universal adsorption theory” (UAT) extends the principle of corresponding states for gas compressibility to describe the excess density of an adsorbed phase at comparable reduced conditions. The UAT helps to describe experimental trends and provide predictive capacity for extrapolation from one adsorption isotherm to that of a different adsorbate. Here, we extend the UAT to a flexible metal–organic framework (MOF) as a function of adsorbate, temperature, and pressure. When considered via the UAT, the adsorption capacity and GO pressure of multiple gases to Cu(dhbc) 2 (4,4′-bpy) [H 2 dhbc = 2,5-dihydroxybenzoic acid, bpy = bipyridine] show quantifiable trends over a considerable temperature and pressure range, despite the chemical and structural heterogeneity of the adsorbent. Exceptions include quantum gases (such as H 2 ) and prediction of maximum capacity for large and/or polar adsorbates. A method to derive the heat of gate opening and heat of expansion from experimental trends is also presented, and the parameters can be treated as separable and independent over the temperature and pressure range studied. We demonstrate the relationship between the UAT and the common Dubinin analysis, which was not previously noted. [ABSTRACT FROM AUTHOR]