Instituto Politécnico Nacional, Escuela Nacional de Ciencias Biológicas, Departamento de Ingeniería Bioquímica, Avenida Wilfrido Massieu s/n, Unidad Profesional Adolfo López Mateos, Delegación Gustavo A. Madero, Ciudad de México, México.
PLoS One. 2020 Jan 21;15(1):e0227953. doi: 10.1371/journal.pone.0227953. eCollection 2020.
Continuous fixed-bed column studies were carried out, utilizing acorn shell from Quercus crassipes Humb. & Bonpl. (QCS), in order to remove total chromium and Cr(VI) from aqueous solution. Effects of various fixed-bed column parameters such as influent solution pH, influent flow rate, QCS bed height, and influent Cr(VI) concentration were investigated. Results from the fixed-bed column experiments demonstrate that total chromium biosorption and Cr(VI) removal by QCS depend strongly on the pH of influent solution. The highest capacities for Cr(VI) removal and total chromium biosorption are about 181.56 and 110.35 mg g-1 and are achieved at influent solution pH of 1.0 and 2.0, respectively. Besides this, total chromium biosorption capacities increased from 104.25 to 116.14 mg g-1, 109.07 to 117.44 mg g-1, and 85.02 to 129.87 mg g-1, as bed height, inlet flow rate, and influent Cr(VI) concentration increased from 1.7 to 6.5 cm, 0.25 to 1 mL min-1, and 50 to 400 mg L-1, respectively. The dose-response model defines the entire breakthrough curve for total chromium biosorption onto QCS, under all experimental conditions. X-ray photoelectron spectroscopy (XPS) and biosorption kinetic studies revealed that QCS is able to remove toxic Cr(VI) from acidic liquid solution by means of a complex mechanism that involves the binding of Cr(VI) oxyanions to positively charged groups present at the QCS surface, after which the Cr(VI) species are reduced to Cr(III) by adjacent electron donor groups, and the generated Cr(III) ions then become partially bound to the QCS biomass and partially released into the liquid phase. Results show that QCS can be employed as an easily accessible, abundant, eco-friendly, and inexpensive biosorbent for the removal of total chromium and Cr(VI) from Cr(VI) solutions, in continuous operation.
进行了连续固定床柱研究，利用来自 Quercus crassipes Humb. & Bonpl.（QCS）的橡果壳，以从水溶液中去除总铬和 Cr(VI)。研究了各种固定床柱参数的影响，如进水溶液 pH 值、进水流量、QCS 床层高度和进水 Cr(VI)浓度。固定床柱实验的结果表明，QCS 对总铬的生物吸附和 Cr(VI)的去除强烈依赖于进水溶液的 pH 值。在进水溶液 pH 值为 1.0 和 2.0 时，Cr(VI)的最大去除量和总铬的生物吸附量分别约为 181.56 和 110.35 mg g-1。此外，随着床层高度、入口流速和进水 Cr(VI)浓度从 1.7 至 6.5 cm、0.25 至 1 mL min-1和 50 至 400 mg L-1的增加，总铬的生物吸附量从 104.25 增加到 116.14 mg g-1、109.07 增加到 117.44 mg g-1、85.02 增加到 129.87 mg g-1。剂量响应模型定义了在所有实验条件下，总铬在 QCS 上的生物吸附整个穿透曲线。X 射线光电子能谱（XPS）和生物吸附动力学研究表明，QCS 能够通过一种复杂的机制从酸性液体溶液中去除有毒的 Cr(VI)，该机制涉及 Cr(VI)含氧阴离子与 QCS 表面上带正电荷的基团结合，然后 Cr(VI)物种被相邻的电子供体基团还原为 Cr(III)，生成的 Cr(III)离子随后部分与 QCS 生物质结合，部分释放到液相中。结果表明，QCS 可以作为一种易于获取、丰富、环保且廉价的生物吸附剂，用于连续运行中从 Cr(VI)溶液中去除总铬和 Cr(VI)。
