No abstract

No information is currently available on potential environmental impact of boric acid solvent extraction from salt-lake brine although boron production is important for industry, agriculture, and human well-beings. Life cycle assessment (LCA) was firstly used by this study to evaluate the environmental impact of boron production using extraction method with the functional unit of 1-ton boric acid. CO 2 was the pollutant with the highest emission amount among the target pollutants, while both extraction and reverse extraction stages contributed to 61.6% of total emission amount for the boron extraction technique. Global warming potential (GWP) and acidification potential (AP) of producing 1-ton boric acid by extraction technique reached 5.52 × 10 3 kg CO 2 eq and 28.0 kg SO 2 eq, respectively. Extraction/dry stage contributed to the highest/ lowest percentage of environmental impact indices by following the order of extraction > reverse extraction > acidification > dry. Life cycle cost for 1 ton of boric acid was estimated as $1054.83 with 67.5% of internal cost. Approximately 1.59 ton of indirect water and 6010 kWh of electricity were consumed to produce 1 ton of boric acid. The emission amounts of pollutants for nanofiltration boron-production technique were 1.4-1.7 times those for extraction technique. GWP and AP of boron extraction production were comparable with those of the other production processes. The findings of this study will provide the theoretical basis and quantitative data for the sustainable development and cleaner production of boron industry.

The eastern/western Taijinar Salt Lake in Qaidam Basin is rich in lithium and boron resources. Chemical speciation of boron and lithium is conducive to identify the migration way and enrichment of heavy metals which might cause certain effects on the environment of salt-lake area. A total of 28 surface sediment samples were collected from the Taijinar Salt Lake in June of 2020 to investigate the distribution, speciation and sources of boron and lithium in salt-lake sediments. The results showed that the average content of boron/lithium was low with value of 1.6/3.4 µg kg −1, while that of the other elements in sediments ranging from 0.035 µg kg −1 (Cd) to 48.20 mg kg −1 (As) by following the order of As > Pb > Hg > Zn > Cr > Cd. Boron and lithium in sediments were mainly bound to Fe-Mn oxide and residual fractions with the average proportion of 29.87% and 35.36% for boron as well as 32.18% and 31.43% for lithium. Pb mainly existed in carbonate and residual fraction, while Zn mainly existed in the Fe-Mn oxide and residual bound with average value of 40.56% and 43.32%, respectively. Hg/Cr mainly existed in the residual with the average value of 58.68%/84.18%, while Cd mainly existed in the Fe-Mn oxide and residual fraction with an average proportion of 26.52% and 30.89%, respectively. As mainly existed in Fe-Mn oxide, residual, and organic fraction with an average proportion of 30.20%, 32.61% and 21.92%, respectively. Elements including Zn, Cr and Pb had a certain influence on the speciation of boron and lithium based on the correlation analysis. The enrichment of Cd, Cr and Pb might be mainly caused by anthropogenic sources. The findings of this study will provide some basic information on the important elements including lithium and boron in the salt-lake areas.