Environmental Materials Division, CSIR-National Environmental Engineering Research Institute (NEERI), Nagpur, 440020, India.
St. Aloysius Institute of Technology, Gaur, Jabalpur, 482020, India.
Environ Sci Pollut Res Int. 2022 Aug;29(37):56606-56619. doi: 10.1007/s11356-022-19833-4. Epub 2022 Mar 26.
Silk is the strongest natural biopolymer produced by silk worms possessing superior adsorbent properties and thus extensively used in various applications. The present study involved the preparation of powder form of a silk fibroin materials and their application in adsorption of heavy metals, particularly, iron from aqueous solution. The morphological and structural characteristic properties of this promising materials were examined by using different analytical techniques. Batch experiments were conducted within feasible parametric ranges to understand the effect of dose, time, concentration, pH, and reusability. Silk fibroin was effective for iron adsorption over a wide range of pH 6 to 10. The adsorption removal efficiency of 98% was attained for removal of iron from contaminated water at moderate dose of 0.25 g and contact time of 60 min, which is unprecedented by considering the environment benign nature of the material. The data was examined in different isotherm models wherein it fitted best in Langmuir adsorption model. Similarly, Langmuir isotherm model, with R value of 0.984 and K 0.412 and maximum adsorption capacity as 12.82 mg g, suggests monolayer adsorption. Kinetic study with better R value of 0.941 represented the pseudo-second order kinetics governed by the chemisorption reaction. To understand the practical applicability of silk fibroin, the repeatability study up to 5 cycles were performed. The findings are very encouraging which confirmed the usage of silk fibroin as adsorbent for multiple cycles with marginal decrease in adsorption efficiency. Eventually, the material was tested for iron removal in real contaminated water which revealed its potential and selectivity for removal of iron in different matrix.
蚕丝是由蚕分泌的最强的天然生物聚合物，具有优异的吸附性能，因此被广泛应用于各种领域。本研究涉及丝素蛋白材料的粉末形式的制备及其在吸附重金属方面的应用，特别是从水溶液中吸附铁。通过使用不同的分析技术，研究了这种有前途的材料的形态和结构特性。在可行的参数范围内进行了批量实验，以了解剂量、时间、浓度、pH 值和可重复使用性的影响。丝素蛋白在 pH 值为 6 至 10 的广泛范围内对铁的吸附是有效的。在中等剂量 0.25 g 和 60 min 的接触时间下，从受污染的水中去除铁的去除效率达到 98%，考虑到材料的环境友好性，这是前所未有的。数据在不同的等温线模型中进行了检查，其中最符合朗缪尔吸附模型。同样，Langmuir 等温线模型，R 值为 0.984，K 值为 0.412，最大吸附容量为 12.82mg g，表明单层吸附。具有更好的 R 值 0.941 的动力学研究表明，受化学吸附反应控制的准二级动力学。为了了解丝素蛋白的实际适用性，进行了多达 5 个循环的可重复性研究。研究结果非常令人鼓舞，证实了丝素蛋白作为吸附剂的多次循环使用，吸附效率略有下降。最终，该材料在实际受污染的水中进行了铁去除测试，结果表明其在不同基质中去除铁的潜力和选择性。
