Department of Chemical Engineering, Indian Institute of Technology Guwahati, Assam 781 039, India.
Chemosphere. 2013 Oct;93(7):1366-71. doi: 10.1016/j.chemosphere.2013.08.021. Epub 2013 Sep 18.
Microalga species are potential scavengers of heavy metals. The active functional groups of a number of biomaterials are capable to detoxify Cr(VI) to Cr(III). A 2nd order kinetic model was developed in terms of concentration of protonated acidic groups of Spirulina sp. biomass for the reduction of Cr(VI) into Cr(III). Cr(VI) reduction reaction grounded on the concentration of functional groups was validated over a broad range of pH, temperature and anionic strength. Lower pH favoured Cr(VI) reduction reaction and the experimental results well fitted to the kinetic model. The overall rate constant, kt, decreased logarithmically from 22.7 to 2.8 mM⁻¹ s⁻¹ with rise of pH from 0.5 to 6.0. Whereas, k(t) increased nearly by 23% with elevation temperature from 25 to 45 °C. Higher concentration (>0.235 mM) of background anions (Cl⁻, SO₄²⁻ and NO₃⁻) was resulted in decreases in k(t) values. The rate constant expression developed can be employed to quantify Cr(VI) reduction into Cr(III) using Spirulina biomass.
微藻物种是重金属的潜在清除剂。许多生物材料的活性官能团能够将六价铬（Cr(VI)）还原为三价铬（Cr(III)）。根据螺旋藻生物质质子化酸性基团的浓度，开发了一个二阶动力学模型，用于还原 Cr(VI)为 Cr(III)。基于官能团浓度的 Cr(VI)还原反应在较宽的 pH 值、温度和阴离子强度范围内得到了验证。较低的 pH 值有利于 Cr(VI)还原反应，实验结果与动力学模型拟合良好。在 pH 值从 0.5 升高到 6.0 时，整体速率常数 k(t)从 22.7 下降到 2.8 mM⁻¹ s⁻¹。而 k(t)随温度从 25°C 升高到 45°C 上升了近 23%。较高浓度（>0.235 mM）的背景阴离子（Cl⁻、SO₄²⁻和 NO₃⁻）导致 k(t)值下降。所开发的速率常数表达式可用于使用螺旋藻生物质定量还原 Cr(VI)为 Cr(III)。
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