Abstract The use of guava seeds (GS) and acid-modified guava seeds (MGS) for the removal of Cr(VI) from aqueous solutions was investigated. Batch-type experiments were performed with Cr(VI) aqueous solutions and biosorbents to determine the kinetic and equilibrium sorption parameters. Results indicated that GS and MGS were capable of reducing and remove Cr(VI) from solutions, but the reduction was only observed at some experimental conditions. Infrared analysis showed that several functional groups were involved in the reduction, and biosorption of Cr(VI), particularly alcohol, phenolic, carboxylic, and methoxymethyl structures. The mechanisms of reduction and biosorption depended upon the type of biosorbent, pH, and temperature of the system. The pseudo-second-order kinetic model describes the kinetic sorption data, and the Langmuir-Freundlich (L-F) model describes the isotherm data in most cases. Significantly high total chromium biosorption capacities were obtained. Acid modification of guava seeds improves chromium biosorption performance.

中文翻译：

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酸改性番石榴种子从水溶液中还原和生物吸附 Cr(VI)：动力学和平衡研究

摘要 研究了使用番石榴籽 (GS) 和酸改性番石榴籽 (MGS) 从水溶液中去除 Cr(VI)。使用 Cr(VI) 水溶液和生物吸附剂进行批量型实验，以确定动力学和平衡吸附参数。结果表明 GS 和 MGS 能够从溶液中还原和去除 Cr(VI)，但仅在某些实验条件下观察到还原。红外分析表明，几个官能团参与了 Cr(VI) 的还原和生物吸附，特别是醇、酚、羧基和甲氧基甲基结构。还原和生物吸附的机制取决于生物吸附剂的类型、pH 值和系统温度。拟二级动力学模型描述了动力学吸附数据，并且 Langmuir-Freundlich (LF) 模型在大多数情况下描述了等温线数据。获得了显着高的总铬生物吸附能力。番石榴种子的酸改性提高了铬的生物吸附性能。