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Recently, layered double hydroxides (LDHs) have been extensively researched for their anion exchange capabilities and exhibit a layered structure with a host layer of octahedrally coordinated metal cations and a guest layer (interlayer) of anions. In this study, we synthesized a CM-β-CD•Zn–Al LDH by anion exchange method to study the anionization of cyclodextrin (CD) to promote its incorporation into the LDH interlayers and its stability therein. Ni2+ adsorption by the CMCD•Zn–Al LDH by the anion exchange method was compared with the results co-precipitation method. The X-ray diffraction spectra of NO3•Zn–Al LDH and CM-β-CD•Zn–Al LDH synthesized by the anion exchange method exhibit that the product peaks were attributable to Z n 6 A l 2 O H 16 C O 3 4 H 2 O and possessed an LDH structure. Furthermore, all CM-β-CD•Zn–Al LDHs exhibited the presence of some CM-β-CD. The CM-β-CD•Zn–Al LDH was hypothesized to be composed of two types of layers: a CM-β-CD layer in which two molecules of CM-β-CD7-, with cavity axes perpendicular to the LDH host layer, are vertically overlaid, and a NO3-type Zn–Al LDH layer used as a precursor. CM-β-CD•Zn–Al LDH adsorbed Ni2+ in an aqueous solution. To determine whether Ni2+ adsorption by the CM-β-CD•Zn–Al LDH is driven chemically or physically, we fitted the data to the Freundlich and Langmuir adsorption models; the results showed that Ni2+ adsorption by the CM-β-CD•Zn–Al LDH is consistent with the Langmuir equation and could be considered a chemical adsorption. [ABSTRACT FROM AUTHOR]

In this study, we developed a one-pot wet ball-milling method for the recovery of highly pure copper wire, poly(vinyl chloride) (PVC) coating, and diisononyl phthalate (DINP) plasticizer from waste wire harnesses. n-Butyl acetate, acetone, or ethyl acetate was used as the solvent to simultaneously extract the DINP and separate the Cu and PVC, by swelling the PVC coating and physically impacting the cables with milling balls, achieving the whole process in one pot. The swelling ratios suggested the order of solvent power for PVC as n-butyl acetate > acetone > ethyl acetate at ~ 25 °C after 80-min submersion; while on increasing temperature, this order changed to acetone > n-butyl acetate > ethyl acetate. Due to the temperature rise induced by oblique ball-to-ball and ball-to-reactor collisions during milling, acetone exhibited the best separation efficiency, achieving complete separation of 20-cm-long cables in 40-min wet milling at 25 rpm, with the simultaneous, nearly quantitative recovery of DINP. Of the recovered Cu wires, nearly ~ 90% exceeded 10-cm lengths, which facilitated quantitative recovery in the separation step. Furthermore, 100% of the de-plasticized PVC was recovered, and ~ 85% of the solvent was regenerated by distillation for re-use. [ABSTRACT FROM AUTHOR]

With the ultimate aim of reducing the volume of radioactive-cesium-contaminated soil generated by the nuclear power plant accident in Fukushima Prefecture in 2011, this study focuses on the desorption of Cs+ ions from minerals that strongly adsorb Cs+, such as clay, using the ion-association reagents sodium tetrakis(4-fluorophenyl)borate hydrate (NaTFPB) and sodium tetraphenylborate (NaTPB) under mild conditions. A-type zeolite was selected as a representative aluminosilicate mineral with a high cesium adsorption capacity. NaTFPB exhibits stronger hydrophobic interactions with Cs+ and improved Cs+ compared to NaTPB; a desorption efficiency of 89.4% was achieved at a 10:1 NaTFPB/cesium molar ratio. [ABSTRACT FROM AUTHOR]

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• Co-pyrolysis of PVC with cellulose, xylan, and milled wood lignin was performed. • Our approach improved compound separation ability and detected numerous pyrolyzates. • Hierarchical cluster analysis was used to rapidly screen for pyrolytic interactions. • Hydrogen chloride from PVC catalyzed dehydration of levoglucosan from cellulose. • Hydrogen chloride enhanced conversion of methoxyphenols into phenolic compounds. Co-pyrolysis of plastic/lignocellulosic biomass mixtures produces an extremely complex assortment of pyrolyzates. In the present work, co-pyrolysis of PVC with cellulose or xylan or milled wood lignin was conducted by employing pyrolysis–two-dimensional gas chromatography–time-of-flight mass spectrometry (Py-GC × GC-TOFMS) with the aim of achieving high throughput and comprehensive analysis of the complex pyrolyzates. Then, hierarchical cluster analysis (HCA), which is an algorithm that groups similar objects into groups called clusters, was applied to accomplish rapid screening for compounds influenced by pyrolytic interactions. This combined approach improved compound separation and identifiability and allowed the subsequent easy identification of new compounds and compounds increased or decreased by pyrolytic interactions during co-pyrolysis. The change in distribution during co-pyrolysis clearly suggests the occurrence of HCl-catalyzed dehydration of anhydrosugars and conversion of methoxyphenols into phenolic compounds. Thus, this study reveals the effectiveness of the approach combining Py-GC × GC-TOFMS with HCA, which promises to contribute to the acceleration of research on pyrolytic interactions. The understanding of pyrolytic interactions gained thereby will be crucial for maximizing the yield and quality of desired chemicals and fuels from plastic/lignocellulosic biomass. [ABSTRACT FROM AUTHOR]

The utilization and storage of surplus waste bagasse in underdeveloped sugar mills is problematic due to limited space within the sugar factories and pollution from bagasse debris, thus, pyrolysis offers a possible solution for the clearance of factory bagasse wastes. In this study, Fijian sugarcane bagasse was subjected to pyrolysis, and the effects of combined acetic acid (CH3COOH) pretreatment and high temperature on the distribution of gaseous products were investigated. Bagasse wastes delivered from Fiji were pretreated with different concentrations of CH3COOH (1, 3, 6, and 9 mol L−1 (M)) to partially hydrolyze cellulose, hemicellulose, and lignin. The pretreatment disrupted the bagasse cell structures and enhanced bagasse pyrolysis. The gas yield from untreated bagasse at 500 °C (117.7 mL g−1) significantly increased (350.4 mL g−1) with the combination of 1 M CH3COOH pretreatment and thermal cracking at 800 °C. This study will aid the recovery of energy or chemical feedstock from surplus Fijian bagasse, which cannot be otherwise used effectively. [ABSTRACT FROM AUTHOR]

This study undertook the testing of Cu2+ and Ni2+ adsorption using synthesized oxalic acid-crosslinked chitosan (CTS)-modified montmorillonite (MMT), as well as a kinetic analysis and equilibrium analysis. We believe that our study makes a significant contribution to the literature because we showed that the interlayer distance of untreated MMT was increased from 1.23 to 2.05–2.21 nm, and thus verified the intercalation of CTS into the MMT interlayer. The maximum adsorption of Cu2+, as calculated using the Langmuir equation, was significantly higher for oxalic acid-crosslinked CTS-modified MMT, relative to untreated MMT or the non-crosslinked CTS-modified-MMT. The oxalic acid-crosslinked CTS-modified MMT could also take up more Cu2+ than Ni2+ from a solution containing a mixture of Cu2+-Ni2+. The selective adsorption of oxalic acid-crosslinked CTS-modified-MMT (i.e. Ni2+ < Cu2+) is governed by the selective adsorption of CTS and the oxalic acid. This reveals the effect of the complex formation with CTS and oxalic acid. [ABSTRACT FROM AUTHOR]

Effective and efficient dehalogenation for automobile shredder residue (ASR) was successfully carried out in an NaOH/ethylene glycol solvent at 190 °C with an up-scale ball mill reactor. The element content and plastic in different fractions of ASR samples were analyzed. 1.2 ± 0.4 wt% Cl and 0.1 ± 0.1 wt% Br were measured in the fine mixture of ASR; consequently, dehalogenation was essential to mitigate the formation of hazardous compounds during thermal treatment. Sufficiently high dechlorination and debromination capacities were obtained by adjusting ball numbers and NaOH content, and the effectiveness of the treatment for throughput scale-up was confirmed. Dehalogenated ASR achieved lower than 0.1 wt% of Cl and negligible Br content, making the product suitable for feedstock recycling to recover metals and petrochemicals. We performed a life cycle assessment on the up-scale dehalogenation process and identified two beneficial impacts in comparison with the landfilling of ASR: reductions in carcinogenic effects and ecotoxicity. To mitigate impacts on climate change and resource depletion, improving dehalogenation efficiency by scaling up the throughput, enhancing the heat insulation system, and including a process for ethylene glycol recycling need to be considered. [ABSTRACT FROM AUTHOR]

Pb, Cu, Zn, Mn, and Cr were removed from municipal solid waste fly ash through chloride volatilization method using poly(vinyl chloride) (PVC) as the chlorinating agent. To investigate the effective utilization of PVC, chloride volatilization at 700–900 °C was conducted for 0–120 min under three conditions: elevated heating (~ 40 °C/min), isothermal heating, and isothermal heating with Ca(OH)2 as a HCl trapping agent. PVC was a better chlorinating agent than CaCl2 and removed ~ 100% Pb and Zn and ~ 50% Cu and Mn by isothermal heating at 900 °C for 120 min. Ca(OH)2 reduced Pb removal at 700 °C by ~ 20% and Cu removal at 900 °C by ~ 50%; however, it promoted Zn volatilization by 10–20% at all temperatures. The effects of co-existing elements on the chloride volatilization behaviors of these heavy metals were determined by conducting thermodynamic simulations under equilibrium conditions. The combined experimental and thermodynamic approach suggested that Pb and Zn were mainly volatilized as metal chlorides via reaction with the HCl produced by PVC pyrolysis, whereas Mn was volatilized by both CaCl2 and Na2O. Thus, CaO, CaCO3, MgO, and residual carbon in fly ash could inhibit the chlorination of Pb, Cu, and Cr. [ABSTRACT FROM AUTHOR]