Xu Guangxian, chemist, was born in Shaoxing, Zhejiang Province, in November 1920. He graduated from the Department of Chemistry, Shanghai Jiaotong University in 1944, and received his Ph.D. degree with honor from the Department of Chemistry, Colombia University, USA in 1951. After his return to China, he has joined the faculty of Peking University as associate professor (1951-1961) and professor (1961-present) for 55 years. He founded the Research Center of Rare Earth Chemistry in 1986 and the State Key Laboratory of Rare Earth Materials Chemistry and Applications in 1989 at Peking University, and served as director in these institutes for the first two terms. He was elected as a member of the Chinese Academy of Sciences in 1980.
As a leading scientist in rare earth chemistry and separation technology, Prof. Xu established a new theory of countercurrent extraction in 1970s, which is applicable for the separation of a mixture with more than ten components such as rare earths. Based on his comprehensive understanding of rare earth extraction mechanism, he found that the rare earth separation process with countercurrent extraction obeys a rule of constant mixed extraction ratios in the extraction and the scrubbing sections respectively. He deduced all the equations necessary for the calculation of the optimized parameters, such as the numbers of the extraction and the stripping stages, the ratios of the flowrates of the feed, the extractant and the stripping solutions.
Based on this theory, he and his coworkers built up a theoretical model to simulate the dynamic process of the cascade from starting to the steady state, and established an “expert design system,” with which an optimized flow sheet of a new separation process may be designed and all necessary parameters may be calculated in a couple of days, at any given composition of the raw rare earth mixture and any requirement of the purities of products. The new extraction separation flow sheet can be used directly for industrial production without timeconsuming and expensive laboratory experiments, and medium scale tests, and have been extensively used in the major rare earth separation factories in China with great success. So that China now holds 90% share of the worlds total production and foreign trade of the pure rare earth compounds.
Prof. Xus academic contributions covered several fields in chemistry, including physical chemistry, inorganic chemistry, and theoretical chemistry. In 1980, he proposed and approved by experiments that the clear and transparent organic phase in solvent extraction is really a microemulsion, which disclosed a new way to the study of the solvent extraction with the interfacial chemistry, and it has become a basic and interdisciplinary field in solvent extraction. He has also been an active and creative scientist in both theoretical and experimental chemistry of lanthanides, and broadened the novel area on molecularbased rare earth functional materials.
Due to his distinguished contribution, Prof. Xu has been awarded twice the National Natural Science Prize (Second Class and Third Class in 1987), twice the National Scientific and Technological Progress Prize (Second Class in 1998 and Third Class in 1991), and HLHL Prize for Scientific and Technological Progress in 1994. He has also won many other academic prizes awarded by the Ministry of Education of China, Ministry of Metallurgy of China, Beijing Municipal Government, and Guangdong Provinceial Government. As an outstanding professor in chemistry education, Prof. Xu published several important textbooks, among which Structure of Matter was awarded a Supreme Prize of College Textbooks, the unique awardee in chemistry up to date.