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With the application of resins in various fields, numerous waste resins that are difficult to treat have been produced. The industrial wastewater containing Cr(VI) has severely polluted soil and groundwater environments, thereby endangering human health. Therefore, in this paper, a novel functionalized mesoporous adsorbent PPR-Z was synthesized from waste amidoxime resin for adsorbing Cr(VI). The waste amidoxime resin was first modified with H3PO4 and ZnCl2, and subsequently, it was carbonized through slow thermal decomposition. The static adsorption of PPR-Z conforms to the pseudo-second-order kinetic model and Langmuir isotherm, indicating that the Cr(VI) adsorption by PPR-Z is mostly chemical adsorption and exhibits single-layer adsorption. The saturated adsorption capacity of the adsorbent for Cr(VI) could reach 255.86 mg/g. The adsorbent could effectively reduce Cr(VI) to Cr(III) and decrease the toxicity of Cr(VI) during adsorption. PPR-Z exhibited Cr(VI) selectivity in electroplating wastewater. The main mechanisms involved in the Cr(VI) adsorption are the chemical reduction of Cr(VI) into Cr(III) and electrostatic and coordination interactions. Preparation of PPR-Z not only solves the problem of waste resin treatment but also effectively controls Cr(VI) pollution and realizes the concept of "treating waste with waste". [ABSTRACT FROM AUTHOR]

Industrial solid waste has a wide range of impacts, and it is directly or indirectly related to land, atmosphere, water, and other resources. Industrial solid waste has a large amount of production, complex and diverse components and contains a variety of harmful substances. However, as industrial by-products, it also has a lot of available value. Industrial solid waste has been continuously studied in water treatment due to its special composition and porous and loose structure. It is known that there are few reviews of various industrial solid wastes in the field of wastewater treatment, and most of them only discuss single industrial solid waste. This paper aims to sort out the different studies on various solid wastes such as fly ash, red mud, wastewater sludge, blast furnace slag and steel slag in dyeing, heavy metal, and phosphorus-containing wastewater. Based on the modification of industrial solid waste and the preparation of composite materials, adsorbents, coagulants, catalysts, filtration membranes, geological polymers, and other materials with high adsorption properties for pollutants in wastewater were formed; the prospect and development of these materials in the field of wastewater were discussed, which provides some ideas for the mutual balance of environment and society. Meanwhile, some limitations of solid waste applications for wastewater treatment have been put forward, such as a lack of further researches about environment-friendly modification methods, application costs, the heavy metal leaching, and toxicity assessment of industrial solid waste. [ABSTRACT FROM AUTHOR]

To effectively separate and recover Co(II) from the leachate of spent lithium-ion battery cathodes, we investigated solvent extraction with quaternary ammonium salt N263 in the sodium nitrite system. NO2− combines with Co(II) to form an anion [Co(NO2)3]−, and it is then extracted by N263. The extraction of Co(II) is related to the concentration of NO2−. The extraction efficiency of Co(II) reaches the maximum of 99.16%, while the extraction efficiencies of Ni(II), Mn(II), and Li(I) are 9.27%–9.80% under the following conditions: 30vol% of N263 and 15vol% of iso-propyl alcohol in sulfonated kerosene, the volume ratio of the aqueous-to-organic phase is 2:1, the extraction time is 30 min, and 1 M sodium nitrite in 0.1 M HNO3. The theoretical stages require for the Co(II) extraction are performed in the McCabe—Thiele diagram, and the extraction efficiency of Co(II) reaches more than 99.00% after three-stage counter-current extraction with Co(II) concentration of 2544 mg/L. When the HCl concentration is 1.5 M, the volume ratio of the aqueous-to-organic phase is 1:1, the back-extraction efficiency of Co(II) achieves 91.41%. After five extraction and back-extraction cycles, the Co(II) extraction efficiency can still reach 93.89%. The Co(II) extraction efficiency in the actual leaching solution reaches 100%. [ABSTRACT FROM AUTHOR]

In this study, the adsorption capacity of organo-montmorillonites (OMt) modified with cationic surfactants and chelating reagent toward binary-component, heavy metal and organic pollutant, in aqueous solution was investigated through batch experiments. The characteristics of the OMt were analyzed by X-ray diffraction (XRD), Fourier transform infrared spectra (FTIR), Specific surface area (BET), respectively, confirming that hexadecyl trimethyl ammonium chloride (CTAC), ethylene diamine tetraacetic acid (EDTA) and 1,6-diaminohexane (DA) were successfully introduced into Na+-Mt. Comparing with stronger Zn2+ removal efficiency onto EDTA-Mt and DA-Mt dominated by forming complexes in the binary-component systems, CTAC–EDTA-Mt and CTAC–DA-Mt gained a huge edge in uptaking phenol controlled by layer partition. Factors containing the initial Zn2+/phenol concentration and the competitive adsorption where the Zn2+, Pb2+, Cd2+ and phenol/Zn2+, p-nitrophenol, phenylamine and phenol coexisted in the aqueous solution were shown in the paper. Furthermore, the desorption of Zn2+ and phenol on the CTAC–DA-Mt was investigated by series experiments under various conditions (with the type of chemical reagents, variable concentration of desorbent and contact time). The results showed HCl solution had higher efficiency on desorbing Zn2+ over phenol onto the CTAC–DA-Mt. CTAC–EDTA-Mt and CTAC–DA-Mt had potential applications in dealing with the wastewater where heavy metals and organic pollutants coexist. [ABSTRACT FROM AUTHOR]

Al pillared montmorillonites (Al-PILM) were synthesized by the reaction of Na-montmorillonite (Na-Mt) and hydroxy-Al cation after pre-intercalation with dodecylamine (DA) under different drying methods and calcination temperatures. The results showed that Al-PILM dried at room temperature was more crystalline and had larger c-axis spacing, d, BET specific surface area (S) and microporous volume, compared to those by common air-blast drying or vacuum drying and the superiority in the above properties of the drying methods is as follows: air drying > air-blast drying > vacuum drying. This suggests that natural air drying at room temperature favored the formation of more ordered pillar formation. It was also found that the pre-intercalation of DA had important influence on the physicochemical properties of Al-PILM. When the amount of pre-intercalated DA was 1/2 CEC of Na-Mt, c-axis spacing, d, S and microporous volume of Al-PILM were increased and larger than those prepared without pre-intercalation of DA and the former sample had a more regularly ordered pillar distribution due probably to the reduced pillar density in the montmorillonite interlayers. The DA pre-intercalated PILMs were stable at a larger range of temperatures. With the increase of calcination temperature, the interlayer spacing d value decreased, and the S and microporous volume increased firstly and then decreased. During calcination, the pre-intercalated DA was removed and the hydroxyl-Al cation was converted into the rigid AlO pillars, which resulted in decreased pillar size between Mt layers followed by porosity improvement of Al-PILM. [ABSTRACT FROM AUTHOR]