Chemical Engineering Department, State University of Maringá, Colombo Avenue, 5790, Maringá, Paraná, 87020-900, Brazil.
School of Chemical Engineering, University of Campinas, Albert Einstein Avenue, 500, Campinas, São Paulo, 13083-852, Brazil.
Environ Sci Pollut Res Int. 2018 Sep;25(26):25967-25982. doi: 10.1007/s11356-018-2651-5. Epub 2018 Jul 2.
In this study, particles produced from sericin-alginate blend were used as non-conventional bioadsorbent for removing Cr(III) and Cr(VI) from aqueous solutions. Besides chromium mitigation, the use of sericin-alginate particles as bioadsorbent aims to offer an environmental solution of added value for sericin, which is a by-product from silk industry. Sericin-alginate particles in natura and loaded with Cr(III) and Cr(VI) were characterized using N physical adsorption analysis, optical microcopy, mercury porosimetry, helium pycnometry, scanning electron microscope coupled with energy dispersive X-ray spectrometer, Fourier transform infrared spectrometer, and X-ray diffraction. Kinetic studies on the removal of Cr(III) (at pH = 3.5) and Cr(VI) (at pH = 2) indicate the ion exchange mechanism with Ca(II) and the predominance of external mass transfer resistance. Cr(VI) uptake occurs through an adsorption-coupled reduction process, and bioadsorption equilibrium is reached after ~ 1000 min. Cr(III) bioadsorption occurs faster (~ 210 min). The Cr(VI) bioadsorption is endothermic, as bioadsorption capacity increases with temperature: 0.0783 mmol/g (20 °C), 0.1960 mmol/g (30 °C), 0.4570 mmol/g (40 °C), and 0.7577 mmol/g (55 °C). The three-parameter isotherm model of Tóth best represents the equilibrium data of total chromium. From Langmuir isotherm model, the maximum bioadsorption capacity is higher for total chromium, 0.25 mmol/g (30 °C), than for trivalent chromium, 0.023 mmol/g (30 °C). The comparison of bioadsorption capacities with different biomaterials confirms sericin-alginate particles as potential bioadsorbent of chromium.
在这项研究中，使用丝胶-海藻酸钠混合物制成的颗粒作为非常规生物吸附剂，用于从水溶液中去除 Cr(III) 和 Cr(VI)。除了减少铬污染外，将丝胶-海藻酸盐颗粒用作生物吸附剂的目的是为丝胶提供一种具有附加值的环境解决方案，丝胶是丝绸工业的副产品。用 N 物理吸附分析、光学显微镜、汞孔隙率计、氦比重瓶、扫描电子显微镜结合能量色散 X 射线光谱仪、傅里叶变换红外光谱仪和 X 射线衍射对天然负载 Cr(III) 和 Cr(VI)的丝胶-海藻酸盐颗粒进行了表征。去除 Cr(III)（在 pH = 3.5）和 Cr(VI)（在 pH = 2）的动力学研究表明，离子交换机制与 Ca(II)有关，外部传质阻力占主导地位。Cr(VI)的吸收是通过吸附耦合还原过程发生的，在 1000 min 后达到生物吸附平衡。Cr(III)的生物吸附发生得更快（210 min）。Cr(VI)的生物吸附是吸热的，因为生物吸附容量随着温度的升高而增加：0.0783 mmol/g（20°C）、0.1960 mmol/g（30°C）、0.4570 mmol/g（40°C）和 0.7577 mmol/g（55°C）。Tóth 三参数等温模型最能代表总铬的平衡数据。从 Langmuir 等温模型来看，30°C 时，总铬的最大生物吸附容量（0.25 mmol/g）高于三价铬（0.023 mmol/g）。与不同生物材料的生物吸附容量比较证实，丝胶-海藻酸盐颗粒是潜在的铬生物吸附剂。
