关键词: 烃基黄药, 生物降解度, 降解动力学, 机理

Abstract: Biodegradation extent of several ordinary alkyl xanthate collectors was determined according to the testing standard for biodegradability of surfactants ( GB/T15818-2006) , and the kinetic model of biodegradation was also discussed. Meanwhile, the impact of molecular structure on biodegradability was studied as well. The results indicates that under the laboratory conditions, the biodegradation extent of ethyl xanthate, isopropyl xanthate, n-butyl xanthate, isobutyl xanthate, n-amyl xanthate can reach at 96. 36% , 81. 76%, 73. 74%, 63. 37%, 60. 30% in 8 days, respectively. All of their aerobic biodegradation follows the first order enzyme reaction kinetics equation. The biodegradation and rate constant of alkyl xanthates with different structure are comparatively different, the rate constant of collectors follows the order of k_ethyl >k_butyl > k_amyl > k_isopropyl > k_isobutyl . With an increase in length of carbon chain and number of alkyl lateral chain, the biodegradability of the collectors decreases, while the disappearing time (DT-90) and half-life time ( t_1/2 ) of the collectors increase. Comparing to the alkyl chain length, the branch has a more significant effect on the degradability of alkyl xanthates. Through the preliminary study of the biodegradation mechanism of xanthates, it is found that CS₂, ROCSSH and thiocarbonate are the main products of biodegradation of xanthates and a small amount of oil-like dixanthogen droplets are also produced.

Key words: alkyl xanthates, biodegradation extent, degradation kinetics, mechanism