Department of Applied Science and Technology, Anna University, Chennai, Tamil Nadu, 600025, India.
Biofouling and Thermal Ecology Section, Water and Steam Chemistry Division, BARC Facilities, Kalpakkam, Tamil Nadu, 603102, India; Homi Bhabha National Institute, Mumbai, 400094, India.
Chemosphere. 2021 Apr;269:128722. doi: 10.1016/j.chemosphere.2020.128722. Epub 2020 Nov 2.
Increasing number of reports on uranium contamination in groundwater bodies is a growing concern. Deinococcus radiodurans biofilm-based U(VI) bioremediation has great potential to provide solution. This study focuses on the kinetic modelling of uranium biosorption by D. radiodurans biofilm biomass and identification of the functional groups involved in the sequestration process. The effect of temperature, pH and amount of biofilm dry mass were studied using two uranyl ion concentrations (100 and 1000 mg/L). D. radiodurans dry biomass showed good affinity for uranyl ion adsorption. The kinetic experiments revealed that the biosorption process was spontaneous and exothermic in nature. The modelling of kinetic adsorption data revealed that U(VI) sorption by D. radiodurans biofilm biomass follows a pseudo-second-order reaction. Mechanism of U(VI) sorption was suggested to follow an intra-particle diffusion model, which includes covalent bonding between U(VI) and functional groups present on the surface of biofilm biomass, and diffusional barrier acts as a rate limiting step. External mass transfer was the rate-limiting step as evident from Boyd and Elovich plot. Chemical modifications in surface functional groups of biofilm biomass, confirmed the involvement of carboxyl, phosphate, and hydroxyl groups in uranium binding as a significant loss in U(VI) sorption capacity was recorded in these chemically modified biomasses. XRD data indicated the formation of metal deposits, predominantly as uranyl phosphates.
越来越多的关于地下水体内铀污染的报告引起了人们的关注。耐辐射球菌生物膜基 U(VI)生物修复具有提供解决方案的巨大潜力。本研究重点研究了耐辐射球菌生物膜生物量对铀的生物吸附的动力学模型，并确定了参与螯合过程的功能基团。使用两种铀离子浓度（100 和 1000mg/L）研究了温度、pH 和生物膜干质量的量的影响。耐辐射球菌干生物量对铀离子吸附具有良好的亲和力。动力学实验表明，生物吸附过程是自发的和放热的。动力学吸附数据的建模表明，耐辐射球菌生物膜生物量对 U(VI)的吸附遵循拟二级反应。U(VI)吸附的机理被认为遵循内扩散模型，其中包括生物膜生物量表面存在的 U(VI)与功能基团之间的共价键，以及扩散障碍作为限速步骤。从 Boyd 和 Elovich 图可以明显看出，外部传质是限速步骤。生物膜生物量表面功能基团的化学修饰证实了羧基、磷酸根和羟基参与了铀的结合，因为在这些化学修饰的生物量中，U(VI)的吸附容量有显著损失。XRD 数据表明形成了金属沉积物，主要是铀磷酸盐。
