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40 results on '"Zheng, Qingxin"'

6. Simultaneous Material and Chemical Recycling of Waste PET/PE Multi‐Layer Films under Hydrothermal Conditions.

Author

Zheng, Qingxin, Suga, Yoshiki, Su, Yu, Yamaguchi, Hiroya, and Watanabe, Masaru

Subjects
*CHEMICAL recycling, *PLASTIC recycling, *PLASTIC films, *PLASTICS, *WASTE recycling, *POLYETHYLENE terephthalate
Abstract

Multi‐layer plastic films are widely used in various fields especially for packaging, but due to complex composition, it is very difficult to recover single‐material polymers or high‐purity monomers from them after usage. In this study, we proposed a hydrothermal process for recycling PET/PE (PET: Polyethylene terephthalate; PE: Polyethylene) films. PET can be hydrolyzed to monomers of terephthalic acid (TPA) and ethylene glycol (EG). Using a hydrothermal system equipped with two filters, PE, TPA, and EG were collected separately, indicating the simultaneous material and chemical recycling of PET/PE films was firstly achieved. At 300 °C and 10 MPa for 60 min, PET conversion reached around 100 %, and TPA yield of 83.0 % was obtained with a high TPA purity of 96.1 %. In addition, the effect of the holding time on PET conversion, TPA yield, EG yield, and TPA purity was studied. This research opened up a new and sustainable pathway to recycle multi‐layer plastic films in both lab and industry. [ABSTRACT FROM AUTHOR]

Published
2024
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14. Organic Acid‐Based Hydrothermal Leaching of LiFePO4 Cathode Materials.

Author

Li, Zixian, Zheng, Qingxin, Nakajima, Akitoshi, Zhang, Zhengyang, and Watanabe, Masaru

Subjects
CITRIC acid, ELECTROCHEMICAL electrodes, CATHODES, OXALATES, OXALIC acid, LEACHING, GLYCINE, REDUCING agents
Abstract

This study conducts hydrothermal leaching of commercial LiFePO4 (LFPO) cathode materials with oxalic acid, citric acid, or glycine without any other oxidants or reductants. Of these acids, glycine exhibits the weakest leaching behavior, with the leaching efficiency of lithium (Li), iron (Fe), or phosphorus (P) less than 15% even at 200 °C and an acid concentration of 0.8 mol L−1 for 10 min. For oxalic acid, at 200 °C for 10 min, with a pulp density of 30 g L−1 and an acid concentration of 0.8 mol L−1, the leaching efficiencies for Li and P are 100% and 97%, respectively, and 98.5% of Fe precipitates as iron oxalate (FeC2O4) that can be used as a precursor for preparing LFPO cathode materials. Citric acid shows the highest leaching efficiency for Li, Fe, and P, reaching 96%, 100%, and 88%, respectively, at 90 °C for 10 min with a pulp density of 10 g L−1 and an acid concentration of 0.8 mol L−1. The continuous hydrothermal leaching of LFPO cathode materials with citric acid is first achieved. These results clarify the superiority of citric acid over oxalic acid and glycine with respect to the leaching efficiency for Li, Fe, and P from LFPO batteries under hydrothermal conditions. [ABSTRACT FROM AUTHOR]

Published
2024
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39. Novel BaTeMo2O9fine particles synthesized viaa supercritical water routeElectronic supplementary information (ESI) available: XRD pattern of BTM synthesized by solid-state reaction; XPS analysis of BTM particles prepared in supercritical water system. See DOI: 10.1039/c0ce00778a

Author

Zheng, Qingxin, Li, Bo, and Tao, Xutang

Subjects
*X-ray diffraction, *NANOPARTICLES, *BARIUM, *MOLYBDENUM, *SOLID state chemistry, *X-ray photoelectron spectroscopy
Abstract

Pure-phase BaTeMo2O9polycrystals with uniform particle shape and size have been successfully synthesized in a supercritical water system and the novel optical properties were reported. [ABSTRACT FROM AUTHOR]

Published
2011
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