关键词: 生物吸, 金离子, 荔枝壳, 还原, 多酚

Abstract: In order to recover the trace gold ions in the leaching solution,litchi shell was used to prepare gold ion adsorption material. The behavior and mechanism of gold ion adsorption of litchi shell were studied in detail by means of various instruments. Gold particles were observed under the optical microscope,and the X-ray diffraction further confirmed the appearance of gold metal on the modified lychee husk adsorbent,which successfully adsorbed the gold ions in the solution by an electrostatic attraction coupled with the in-situ reduction reaction. XPS analysis confirmed that at least 94. 9% of the gold ions were reduced to gold. The concentration of hydrochloric acid and co-existing base metal impurity ions have little effect on the adsorption efficiency of gold,and in 1 mol / L of HCl,almost 50% of Pd and 35% of Pt are simultaneously adsorbed. In HCl medium of 0. 1 mol / L,100% of Pd and 100% of Pt will be adsorbed simultaneously. Under the concentration of 0. 1 mol / L hydrochloric acid,the saturated adsorption capacity of modified litchi shell for gold was 33. 36 mg / g. During the adsorption process,the ORP (REDOX potential) value of the solution decreased sharply,which also confirmed that the reduction occurred during the adsorption of gold ions by litchi shell. Moreover,the higher the adsorption temperature,the faster the ORP value decreased. The preparation of adsorption materials by litchi shell is simple,low cost,high efficiency and green,and it is expected to be a new technology for recovering trace gold ions from industrial wastewater by adsorption.

Key words: biosorption,gold ions,litchi shell,reduction,polyphenols