Electrodialysis was used to develop a highly efficient process for concentrating and recovering Li from the Li-containing waste solution that is generated after recovering Co and Ni from a leach solution of waste cathode materials of Li ion batteries. The optimum conditions were investigated by comparing the concentration of Li in the concentrated solution, water recovery rate, energy consumption and average flow rate. Limiting current density was also checked. The results showed that the concentration ratio of Li was enhanced up to 133.33% at an applied voltage of 10 V and volume ratio(V D /V C) of 4/1. In order to investigate the concentration ratio of Li based on large volume ratio, the total volume of the Li-containing solution was fixed, and the volume ratio of the dilute solution to the concentrate solution was adjusted to 1/1 to 10/1. The concentration ratio of lithium was increased in the initial stage and then decreased due to the osmotic phenomenon. Finally, an the analysis of the experimental results, including concentration ratio, average flux, and energy consumption, determined that the volume ratio(V D /V C) of 3/1 at 10 V of applied voltage was most efficient and the concentrate ratio of Li increased up to 160.61%.

The aim of this key comparison was to compare capabilities for the preparation and value assignment of gas mixture standards for benzene, toluene, m-xylene, o-xylene and ethylbenzene in nitrogen (subsequently referred to as BTX), maintained at national metrology institutes (NMIs). The range of the nominal amount-of-substance fractions of the comparison standard is 50 nmol/mol to 100 nmol/mol, higher than regulations in most countries for permitted ambient quantities. Another BTX comparison (CCQM-K10) is planned to test the amount-of-substance fraction of 5 nmol/mol to 10 nmol/mol, which is closer to regulatory levels. Eight NMIs participated in CCQM-K7. As pilot laboratory, the National Institute of Standards and Technology (NIST, USA) prepared two 30 L primary standard gas mixtures of BTX in nitrogen using normal gravimetric procedures. Eight 6 L aluminium cylinders were filled from these parent cylinders for the comparison study. Each participating laboratory was shipped one 6 L cylinder to be analysed and then returned to the NIST, which reanalysed the cylinder contents to verify whether the compounds had remained stable throughout the comparison. Although there were indications that the gas mixture was unstable in some of the cylinders, the results indicated that agreement for a majority of the participants was within 5 % relative. The largest deviations were associated with the analysis of ethylbenzene, probably due to lack of experience with this compound. Ethylbenzene is not regulated in most countries, and thus not normally analysed on a routine basis. The relatively high concentration of mixtures used in this comparison may also have caused higher deviations. Normal analytical methods in current use are optimized for the 1 nmol/mol to 10 nmol/mol concentration range, and therefore the higher concentrations were outside the optimum range for analysis. Main textTo reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database, www.bipm.org/kcdb.

In order to apply the silver cementation method using Fe powder from pregnant thiourea leaching solution. Parameters such as the amount of Fe powder addition, agitation speed, and temperature were investigated. The silver cementation rate was increased by the increasing of Fe powder addition, agitation speed, and temperature. The highest silver cementation rate was found when the addition of Fe powder was 50 g/L at the agitation speed of 500 rpm. The silver cementation rate increase with increasing temperature according to the Arrhenius equation and obeys 1 st order kinetics. The activation energy from the kinetics data was found to be between 13.73 KJ/mol and 17.02 KJ/mol. In the XRD analysis, goethite was detected in the precipitate of the thiourea leach solution. This indicates that an oxidation-reduction reaction had occurred in the thiourea solution due to the addition of the Fe powder.