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Microplastics (MPs) migrate by adsorbing heavy metals in aquatic environments and act as their carriers. However, the aging mechanisms of MPs in the environment and the interactions between MPs and heavy metals in aquatic environments require further study. In this study, two kinds of materials, polyamide (PA) and polylactic acid (PLA) were used as target MPs, and the effects of UV irradiation on the physical and chemical properties of the MPs and the adsorption behavior of Cu(II) were investigated. The results showed that after UV irradiation, pits, folds and pores appeared on the surface of aged MPs, the specific surface area (SSA) increased, the content of oxygen-containing functional groups increased, and the crystallinity decreased. These changes enhanced the adsorption capacity of aged MPs for Cu(II) pollutants. The adsorption behavior of the PA and PLA MPs for Cu(II) conformed to the pseudo-second-order model and Langmuir isotherm model, indicating that the monolayer chemical adsorption was dominant. The maximum amounts of aged PA and PLA reached 1.415 and 1.398 mg/g, respectively, which were 1.59 and 1.76 times of virgin MPs, respectively. The effects of pH and salinity on the adsorption of Cu(II) by the MPs were significant. Moreover, factors such as pH, salinity and dosage had significant effects on the adsorption of Cu(II) by MPs. Oxidative complexation between the oxygen-containing groups of the MPs and Cu(II) is an important adsorption mechanism. These findings reveal that the UV irradiation aging of MPs can enhance the adsorption of Cu(II) and increase their role as pollutant carriers, which is crucial for assessing the ecological risk of MPs and heavy metals coexisting in aquatic environments. [ABSTRACT FROM AUTHOR]

Three types of CueR proteins were anchored on the surface of Saccharomyces cerevisiae cells via surface display technology. The surface-engineered cells showed enhanced adsorption capacity and specificity toward Ag (I) in aqueous phase than control groups. A series of experiments were conducted to investigate the resistance of the surface-engineered cells toward environmental changes including pH, temperature, and eluent. The surface-engineered Saccharomyces cerevisiae cells had the highest adsorption capacity of 2.799 mg=g, which was 87.3% higher than original cells. The engineered cells were able to tolerate an acidic environment (pH = 3.0 to 5.0) and high temperature (up to 50°C) with relatively stable adsorption performance. Desorption efficiency was 11% (pH = 5.0, 1 mM eluent), which implied the absorbed Ag (I) ions bonded to the cells with high affinity. [ABSTRACT FROM AUTHOR]

In this study, the relations among the structure, interface adsorption and emulsifying properties of potato protein isolate (PPI) modified by chitosan (CS) were investigated. The results showed that the addition of CS prevented the exposure of tyrosine and tryptophan residues, leading to an increase in the surface hydrophilicity of PPI in the complex system. Meanwhile, the addition of CS decreased the interfacial tension between oil-water and gas-water, and increased the elastic modulus (G′) and the apparent viscosity of PPI in the complex system. Moreover, the emulsion stabilized by the PPI/CS complex exhibited a smaller average particle size and a higher zeta - potential with a better emulsifying stability. In addition, the gel network structure of the emulsion stabilized by PPI/CS complex enhanced to promote the emulsion stability. These results will provide meaningful guidance for the application of CS modified PPI as a novel food emulsifier in the construction of stable Pickering emulsion system. [Display omitted] • The chitosan (CS) increased the surface hydrophilicity of potato protein isolate (PPI). • The CS decreased the interfacial tension between gas-water and oil-water of PPI. • The emulsion stabilized by the PPI/CS complex showed better emulsifying properties. • The emulsion stabilized by the PPI/CS complex showed a smaller average particle size. • The gel network structure of the emulsion stabilized by the PPI/CS complex enhanced. [ABSTRACT FROM AUTHOR]

Abstract: Aluminum-modified hydroxyapatite (Al-HAP) was prepared and characterized using XRD and BET analyses. Al-HAP possessed higher defluoridation capacity (DC) of 32.57mgF−/g than unmodified hydroxyapatite (HAP) which showed a DC of 16.38mgF−/g. The effect of Al/Ca atomic ratio in Al-HAP, solution pH and co-existing anions was further studied. The results indicated that the adsorption data could be well described by the Langmuir isotherm model and the adsorption kinetic followed the pseudo-second-order model. The pH changes during the adsorption process suggested that the surface of Al-HAP was the adsorption sites. The more adsorption sites were formed on Al modified HAP, which possessed abundant surface hydroxyl groups, resulting in higher efficiency of F− removal. Thermodynamic parameters such as ΔG°, ΔH° and ΔS° were calculated in order to understand the nature of adsorption process. The results revealed that the adsorption reaction was a spontaneous and endothermic process. [Copyright &y& Elsevier]

Abstract: The adsorption and decomposition of ethanethiol on GaN (0001) surface have been investigated with first-principles calculations. The DFT calculations reveal that ethanethiol adsorbs dissociatively on the clean GaN (0001) surface to form ethanethiolate and hydrogen species. An up limit coverage of 0.33 for ethanethiolate monolayer on GaN (0001) surface is obtained and the position of the sulfur atom and the tilt angle of the thiolate chain are found to be very sensitive to the surface coverage. Furthermore, the reactivity of ethanethiol adsorption and further thermal decomposition reactions on GaN (0001) surface is discussed by calculating the possible reaction pathways and ethene is found to be the major product. [Copyright &y& Elsevier]

Abstract: The adsorption and decomposition of N2O on GaN (0001) surface has been explored employing density functional theory. Our calculations indicate the parallel adsorbed N2O prefers to be dissociated on the surface, and the dissociated O atom is combined at fcc site, the N–N piece is adsorbed on top site of the surface or desorbed from the surface. From the potential curve of the reaction process of N2O dissociation on the surface, an energy barrier of 0.11eV is derived, which is smaller than that of many widely studied adsorbents for N2O decomposition. [Copyright &y& Elsevier]

Abstract: The adsorption of molecular oxygen on GaN (0001) and surfaces has been explored by employing density functional theory. Our calculations indicate that O2 prefers to be dissociated on these surfaces in parallel orientation, and the dissociated O atoms are combined in fcc site (on both surfaces) or in hcp site (only on GaN surface). The lengths of the formed Gat the two polar surfaces agree with that in ideal Ga2O3 bulk, and these reactions are greatly exothermic. From the potential curve, no obvious energy barrier is found during the process of O2 dissociated adsorption on GaN (0001) surface. [Copyright &y& Elsevier]

Photocatalytic degradation of cationic blue X-GRL (CBX), a strongly adsorbing substrate on TiO2/SiO2, has been investigated by diffuse reflection UV–VIS spectra (UV–visible/DRS) and FT-IR methods. The heterogeneous photocatalysis processes include: adsorption of dye, surface reaction and desorption of final products. The adsorption of CBX onto the surface of TiO2/SiO2 was characterized, and the effect of initial pH of solution on the adsorption was determined. The results demonstrated that CBX was strongly adsorbed at the TiO− site of the catalyst by a penta-heterocyclic-N group. The adsorbed CBX was monitored directly by the UV–VIS/DRS technique during the photodegradation. The results confirmed that the surface photodegradation reaction of CBX was predominantly procedure with the mechanism of direct charge transfer from the semiconductor to the dye adsorbed at TiO⋅ center, and its reaction followed the pseudo-first-order kinetics. This mechanism resulted in the formation of more aliphatic amines and/or amide byproducts, which were further transformed to NH4+. [Copyright &y& Elsevier]

[Display omitted] • Highly negatively charged ultrathin (∼15 nm) InVO 4 NRs were synthesized. • The as-obtained materials exhibited maximum RhB adsorption capacity 780 mg/g. • The InVO 4 NRs showed superior selective adsorption capability towards cationic micropollutants in presence of impurities. • The adsorbents showed robust resilience in a wide pH range and could be effectively recovered by ethanol solution. • The electrostatic attraction was confirmed as the predominant adsorption mechanism. Seeking adsorbents with high adsorption capacity and ease of regeneration is imperative for environmental remediation. Herein, strongly negatively charged two-dimensional (2D) ultrathin InVO 4 nanoribbons (NRs) were synthesized. The material exhibited impressive selective adsorption capabilities towards cationic dyes, and the fitted Langmuir maximum adsorption capacity is 789.7 mg/g when using RhB as a model signal pollutant. The adsorption curve towards Rhodamine B (RhB) fits well with the pseudo-second-order (PSO) reaction. The corresponding adsorption isotherm is confirmed in accordance with the Freundlich model, indicating the adsorption is likely a multi-layer adsorption process. Through examining its adsorption activities with positively charged upconversion nanoparticles (UCNPs) and dyes with different surface charges, the strong electrostatic attraction is found to be the predominant adsorption mechanism. Furthermore, the new adsorbents showed remarkable resilience to even large pH variation (from 3 to 12), and could be rapidly and efficiently regenerated using a mixture of water and ethanol (volume ratio 1:1) in 30 min. These advantages are highly favorable for the application of efficient adsorbents for wastewater treatment and resource recovery. [ABSTRACT FROM AUTHOR]

[Display omitted] • pH-stimulated PDMAEMA microgels were synthesized for selective PFOA recovery. • PDMAEMA microgels showed a maximum PFOA adsorption capacity of ∼ 2632 mg g−1. • The PDMAEMA showed high selectivity for PFOA adsorption in presence of impurities. • PFOA can be easily released and recycled by adjusting the solution pH. • The adsorption mechanism includes electrostatic and hydrophobic interactions. Perfluorooctanoic acid (PFOA) is a high-value chemical which has been widely used in the semiconductor industry. There is currently a lot of work focusing on the removal of low concentration of PFOA due to its potential toxicity, whereas the recovery of high concentration of PFOA from semiconductor wastewater via adsorption could be more valuable. This work reported a novel pH-stimulated poly (dimethyl amino) ethyl methacrylate (PDMAEMA) microgel for selective PFOA recovery. The results showed that the calculated maximum adsorption capacity for PFOA on PDMAEMA microgel is as high as 2632 mg g−1 in the presence of 5% (v/v) isopropyl alcohol (IPA). Electrostatic interaction was considered as the main adsorption mechanism combined with hydrophobic interactions. The strong interactions made the adsorption highly selective; therefore, the components in the water matrix, including acids, metal ions, and organic solvents, would not affect the adsorption performance. Meanwhile, due to the pH responsiveness of PDMAEMA microgels, PFOA could be released easily when the solution pH was adjusted to higher values. Finally, the application mode was investigated by incorporating PDMAEMA microgels into a dense membrane, in which the separation of the microgels in a water system could be effectively achieved. [ABSTRACT FROM AUTHOR]

Abstract: A type of mesoporous ZrO2 was synthesized and its phosphate removal potential was investigated in this study. The adsorption isotherm, pH effect, ionic strength effect and desorption were examined in batch experiments. The adsorption data fitted well to the Langmuir model with which the maximum P adsorption capacity was estimated to be 29.71mgP/g. The amount of phosphate adsorbed increased rapidly in the first 5h and slowly towards the end of the run, suggesting the possible monolayer coverage of phosphate ions on the surface of the adsorbent. The phosphate adsorption tended to increase with a decrease of pH and an increase of ionic strength. A phosphate desorbability of approximately 60% was observed with 0.5M NaOH, which indicated a relatively strong bonding between the adsorbed PO4 3− and the sorptive sites on the surface of the adsorbent. The immobilization of phosphate probably occurs by the mechanisms of ion exchange and physicochemical attraction. Due to its high adsorption capacity, this type of Zirconium oxide has the potential for application to control phosphorus pollution. [Copyright &y& Elsevier]

A series of polyurethane films based on hard segments consisting of toluene diisocyanate and 1,4-butanediol and different soft segments consisting of hydroxyl terminated polybutadiene, hydroxyl terminated polybutadiene/styrene and hydroxyl terminated polybutadiene/acrylonitrile were synthesized by solution polymerization separately. Positron annihilation lifetimes were measured at room temperature for all samples studied. We found that both the free volume size and fractional free-volume decreased with the increase of hard segment content. On the other hand, direct relationship between the gas permeability and the free-volume has been established based on the free-volume parameters and gas diffusivity measured. Experimental results revealed that the free-volume plays an important role in determining the gas permeability. [Copyright &y& Elsevier]

d-g-C 3 N 4 -Fe composites was prepared via a self-assembly and calcination process. According to measurements and density functional theory (DFT) computations, the complexation of iron and pyridinic N of g-C 3 N 4 (Fe‒N) occurred with Fe(III)-π interaction, causing more oxygen vacancies (OVs) with more electrons in iron oxides. In the catalyst air-saturated suspension, the adsorbed pollutants complexed surface Fe(III) through their hydroxyl group donated electrons to around OVs, reducing the surface Fe(III) to Fe(II) and were destructed by Fe(III)-π interaction of the complexation. The addition of H 2 O 2 mainly acted as acceptor being reduced •OH at the OV centers, causing higher degradation rate of pollutants due to both •OH and the surface reaction. However, for the adsorbed hydrophobic pollutants onto the sites of peripheral structure in g-C 3 N 4 , H 2 O 2 was mainly decomposed into O 2 by the synergistic effect of iron species and OVs. Therefore, the catalyst exhibited high Fenton-like efficiency for the degradation of hydroxyl-containing pollutants and hydrophobic pollutants mixing with the former. Our results demonstrate that the Fe(III)-π interaction could carry out the oxidation of pollutants on the catalyst surface, decreasing the consumption of H 2 O 2 , and the role of OVs depends on pollutant adsorption patterns. ga1 • Fe‒N complexation formed between g-C 3 N 4 and iron oxide in d-g-C 3 N 4 -Fe. • More oxygen vacancies produced in iron oxide of d-g-C 3 N 4 -Fe. • Degradation of organics was performed from the surface oxidation rather than •OH. • d-g-C 3 N 4 -Fe shows excellent activity for hydroxyl-containing pollutants degradation. • Efficiency of H 2 O 2 depended on the synergistic effect of OVs and pollutant adsorption. [ABSTRACT FROM AUTHOR]