Li Li,Yifan Bian,Xiaoxiao Zhang,Ying Yao,Qing Xue,Ersha Fan,Feng Wu,Renjie Chen
Nowadays LiFePO 4 cathode develops rapidly for its advantages of long life span, low cost and non-toxicity, especially in electrical vehicle markets. Because of its stable olivine structure, LiFePO 4 is difficult to be recycled by the conventional hydrometallurgical processes as for LiCoO 2 or LiNi x Co y Mn z O 2 . Pyrometallurgical processes consume much energy and release toxic gases. Herein, an effective room-temperature process based on the mechanochemical treatment is proposed to extract metals from LiFePO 4 . Spent LiFePO 4 is co-grinded with low-cost citric acid agent in a ball mill. After grinding, the mixture is dissolved in deionized water and filtrated. With addition of H 2 O 2 , the extraction efficiency of Li reaches as high as 99.35%. Conversely, Fe is hardly extracted with a low extraction efficiency of only 3.86%, indicating a selective recovery of valuable Li element. In addition, when H 2 O is used instead of H 2 O 2 , the mechanochemical reaction changes and the extraction efficiencies of Li and Fe at optimal conditions reach 97.82% and 95.62%, respectively. The Fe impurity is removed as Fe(OH) 3 precipitation by adding NaOH, and Li is recycled as Li 2 CO 3 after reaction with saturated Na 2 CO 3 at 95 °C. This simple and easily-operated process has little negative impact on the environment and has great potential in industrial applications.
In order to reduce the enzyme cost of lignocellulosic enzymatic hydrolysis, upper critical solution temperature (UCST) additives are used to recover and reuse cellulase by regulating the temperature. A sulfobetaine polymer, PSPE, showed a sensitive UCST response in buffer, and its UCST-performance was optimised by adjusting the molecular weight of the polymer. PSPE-3 (Mw = 355.1 kDa) was added to the cellulase buffer at 50 °C, and PSPE-3 and cellulase were co-precipitated by cooling to the room temperature of 25 °C. PSPE-3 and cellulase co-precipitated mainly through hydrophobic interactions via cooling. Compared with octadecyl sulfobetaine (SB3–18), PSPE-3 had a more sensitive UCST response and stronger cellulase recovery ability. Adding only 40% PSPE-3 (accounting for the mass fraction of cellulase) can save more than 50% cellulase in the enzymatic hydrolysis system of eucalyptus chips pre-treated with dilute acid (Eu-DA). However, for the Eu-DA system, adding 100% SB3–18 can only save about 30% of cellulase. In this work, efficient recycling of cellulase was achieved at room temperature by adding UCST-type PSPE. The process is green without consuming acid and alkali, and this work provides a new idea for reducing the production cost of cellulosic ethanol.
Yu Chen,Zhuojia Shi,Zhenghui Liu,Yaxue Shen,Yanlong Wang,Minghui Feng,Qi Liu,Zheng Li
Intensive energy consumption, long leaching time and low leaching efficiency remain key problems in sustainable recycling of solid electrolytes (SSEs) from all-solid-state lithium-ion batteries. Here, we propose a novel strategy to simultaneously overcome these challenges by using representative green solvents, i.e., low-melting mixture solvents (LoMMSs). LoMMSs are novel green solvents with the advantages of low cost, ease of synthesis, biodegradability and tunability. Results show that LoMMSs composed of polyethylene glycol and p -toluenesulfonic acid monohydrate enables 88.5 % Li leaching efficiency from the SSEs within only 1 min at room-temperature. In addition, when using LoMMSs at room temperature for 1 h, the leaching efficiencies of Li, La, Al and Zr from SSEs could reach 97.0 %, 91.7 %, 73.7 % and 83.9 %, respectively. This could be attributed to the coordination and acid–base interactions in the recycling of SSEs.
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