Removal of chloride from ethylene glycol solution using alumina/zeolite membrane as a physical boundary between the organic and aqueous phases

The permeation of Cl^? ions from a NaCl/ethylene glycol (EG) solution during electrodialysis was investigated using alumina and alumina/zeolite membranes. Voltage changes had very little effect on Cl^? permeation through the alumina membrane, suggesting that the driving force for the permeation was concentration-gradient-induced diffusion, and not the electric field. Solvation of the Na⁺ ions by EG resulted in EG migration through the membrane. Replacement of the deionized water (electrolyte) in the anodic cell with NaOH resulted in increased Cl^? permeation, although a greater amount of EG migrated into the NaOH solution as well. No notable difference was observed in Cl^? permeation through the alumina and alumina/zeolite membranes, but EG migration decreased when using the latter membrane, suggesting that EG migration was prevented by the zeolite layer. The proposed alumina/zeolite membrane is, hence, useful for solvent recovery by electrodialysis, but its mechanical stability must be improved for industrial applications.     

Electrodialysis for NaCl/EG solution using ion-exchange membranes

A new concept for the recycling of poly(vinyl chloride) (PVC) has been introduced, including the dehydrochlorination of PVC in ethylene glycol (EG) with NaOH as a reactant, the subsequent separation of NaCl from EG by electrodialysis, and the recovery of chlorine for the synthesis of new PVC. In this work, the separation of NaCl by electrodialysis was investigated. About 98 % of the salt were recovered from EG, with less than 10 % of the EG permeating the membranes after 5 h.     

One-pot wet ball-milling for waste wire-harness recycling

Journal of Material Cycles and Waste Management - 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...     

Alkaline hydrolysis of PVC-coated PET fibers for simultaneous recycling of PET and PVC

Journal of Material Cycles and Waste Management - Polyvinyl chloride (PVC)-coated poly(ethylene terephthalate) (PET) woven fibers are one of the hardest-to-recycle polymeric materials. Herein we...     

Thermal decomposition of tetrabromobisphenol-A containing printed circuit boards in the presence of calcium hydroxide

Journal of Material Cycles and Waste Management - Recycling of printed circuit boards (PCBs) is complicated by the presence of flame retardants containing halogen and phosphorus, as the degradation...     

Transformation of diphenylarsinic acid in agricultural soils

We investigated the transformation and fate of diphenylarsinic acid (DPAA) during incubation in two types of soils (Entisol and Andisol) under aerobic and anaerobic conditions. Under anaerobic conditions only, DPAA was transformed into methyldiphenylarsine oxide by methylation. Under both aerobic and anaerobic conditions, DPAA was degraded to phenylarsonic acid by dephenylation, and phenylarsonic acid was subsequently methylated to form methylphenylarsinic acid and dimethylphenylarsine oxide. The degradation of DPAA in the Andisol was less extensive than in the Entisol. In autoclaved soil under anaerobic conditions, DPAA underwent little degradation during the 24-wk incubation. In unautoclaved soils, the concentration of DPAA in soil clearly decreased after 24 wk of incubation, indicating that DPAA degradation was driven by microbial activity.     

The effects of KI/Se(VI) molar ratio and initial concentration of Se(VI) on the reduction of Se(VI) to Se(IV) by KI

In this study, potassium iodide (KI) was found to be capable of reducing selenium(VI) to selenium(IV). When KI was added to Se(VI) solution, the Se(VI) concentration rapidly decreased with an increase in the KI/Se(VI) molar ratio. By using the potential-pH equilibrium diagram for the selenium/water system, we confirmed that Se(VI) reduced to Se(IV) because the potential of the solution shifted to the stable Se(IV) region upon the addition of KI. This reduction accompanies the oxidation of I⁻ to I₃⁻. The reduction of Se(VI) by KI was found to be effective for concentrated Se(VI) solutions.     

Removal of hydrogen chloride from gaseous streams using magnesium-aluminum oxide

Magnesium-aluminum oxide (Mg-Al oxide) obtained by thermal decomposition of Mg-Al layered double hydroxide (Mg-Al LDH) effectively removed HCl from gaseous streams. HCl removal was greater in the presence of added water vapor at all temperatures examined and increased with decreasing temperature in both the presence and absence of added water vapor. Wet and dry removal of gaseous HCl were attributed to the production of MgCl2 . 6H2O and MgCl2 . 4H2O, respectively. For the wet scrubbing process, the reconstruction reaction of Mg-Al LDH from Mg-Al oxide was the primary mechanism for increased HCl removal.     

Recovery of glass fibers from glass fiber reinforced plastics by pyrolysis

Fiber-reinforced plastic sheets containing unsaturated polyester cross-linked with styrene, CaCO₃ and glass fibers as fillers were pyrolyzed in a helium and steam atmosphere in order to recover glass fibers and valuable organic pyrolysis products. Glass fibers were separated from CaCO₃ and CaO by dissolving calcium salts in hydrochloric acid. Residual organic material was burnt afterwards. Best results were obtained at a pyrolysis temperature of 600 and 700 °C, resulting in a large liquid fraction high in styrene, leaving little residual organic material on the surface of the glass fibers. At a pyrolysis temperature of 500 °C, the degradation of the polymer matrix was incomplete, and at 900 °C, glass fibers were destroyed in the presence of CaO, leaving CaSiO₃ as a product.