Preferentially selective extraction of lithium from spent LiCoO_(2)cathodes by medium-temperature carbon reduction roasting

Lithium recovery from spent lithium-ion batteries(LIBs)have attracted extensive attention due to the skyrocketing price of lithium.The medium-temperature carbon reduction roasting was proposed to preferential selective extraction of lithium from spent Li-CoO_(2)(LCO)cathodes to overcome the incomplete recovery and loss of lithium during the recycling process.The LCO layered structure was destroyed and lithium was completely converted into water-soluble Li2CO_(3)under a suitable temperature to control the reduced state of the cobalt oxide.The Co metal agglomerates generated during medium-temperature carbon reduction roasting were broken by wet grinding and ultrasonic crushing to release the entrained lithium.The results showed that 99.10%of the whole lithium could be recovered as Li2CO_(3)with a purity of 99.55%.This work provided a new perspective on the preferentially selective extraction of lithium from spent lithium batteries.

Kinetics of medium-temperature α-amylase hydrolyzed <i>Huai yam</i>powder

In order to learn the enzymatic characteristics of Huai yam powder with medium-temperatureα-amylase, effects of substrate concentration,enzyme concentration, pH and temperature wereinvestigated. The Michealis-Menten equationwas used to fit the kinetics of the hydrolysis reaction. Experimental results indicate that maximum rate (Vm) is 3.1588 mg/mL·min under the condition of 70&#176;C, pH 7.0 and 0.0200 mg/mL of enzyme concentration. The Michealis constant (Km) is 6.6641 mg/mL. The kinetic model, including the factors such as substrate concentration, enzyme concentration and temperature, was established for the hydrolysis reaction under the temperature range from 40&#176;C - 70&#176;C.

Medium-temperature baking of 1.3 GHz superconducting radio frequency single-cell cavity

Background A reliable and repeatable post-processing technology of improving the performance of 1.3 GHz superconducting radio frequency(SRF)cavities is one of the critical technologies for the ILC and XFEL and ERL projects.Methods Three 1.3 GHz single-cell cavities were fabricated and received a baking in temperature 330℃,while the interior of the cavity stayed in ultra-high vacuum(UHV).The cavities were also vertical-tested after electropolishing(EP)with 120℃48-h baking and with nitrogen doping separately for a comparison.Results The Q_(0) of 1.3 GHz single cavity after medium-temperature baking can be 2-3×10^(10) in the accelerating gradient range of 2-35 MV/m in the 2 K vertical test in IHEP.Meanwhile,the outer surface oxidation of niobium cavity caused by baking will decrease the performance of the SRF cavity.Conclusions Medium-temperature(250-400℃)baking on the 1.3 GHz single-cell cavity will improve its Q_(0) in 2 K vertical test compared with EP followed by 120℃48-h baking baseline and reach a similar level of nitrogen doping,and the quench field will lower to a typical range of 20-30 MV/m.Meanwhile,the cavity performance is sensitive to the baking time and temperature,which indicates that a tremendous improvement can be made on the current treatment.

Desulfurization kinetics of ZnO sorbent loaded on semi-coke support for hot coal gas

Zn-based sorbent （Z20SC） prepared through semi-coke support in 20 wt% zinc nitrate solution by high-pressure impregnation presents an excellent desulfurization capacity in hot coal gas,in which H2 S can not be nearly detected in the outlet gas before 20 h breakthrough time.The effects of the main operational conditions and the particle size of Z20SC sorbent on its desulfurization performances sorbent were investigated in a fixed-bed reactor and the desulfurization kinetics of Z20SC sorbent removing H2 S from hot coal gas was calculated based on experimental data.Results showed that the conversion of Z20SC sorbent desulfurization reaction increased with the decrease of the particle size of the sorbent and the increases of gas volumetric flow rate,reaction temperature and H 2 S content in inlet gas.Z20SC sorbent obtained from hydrothermal synthesis by high-pressure impregnation possessed much larger surface area and pore volume than semi-coke support,and they were significantly reduced after the desulfurization reaction.The equivalent grain model was reasonably used to analyze experimental data,in which k s=4.382×10-3 exp（-8.270×103/RgT） and Dep=1.262×10-4exp（1.522×104/RgT）.It suggests that the desulfurization reaction of the Z20SC sorbent is mainly controlled by the chemical reaction in the initial stage and later by the diffusion through the reacted sorbent layer.