Melia Patrick M, Busquets Rosa, Ray Santanu, Cundy Andrew B
Kingston University, Faculty of Science, Engineering and Computing Kingston Upon Thames KT1 2EE UK
Surface Analysis Laboratory, University of Brighton, Faculty of Science and Engineering BN2 4GJ UK.
RSC Adv. 2018 Dec 4;8(70):40378-40386. doi: 10.1039/c8ra07877g. eCollection 2018 Nov 28.
Agricultural production results in wastes that can be re-used to improve the quality of the environment. This work has investigated for the first time the use of abundant, un-modified agricultural wastes and by-products (AWBs) from grape, wheat, barley and flax production, to reduce the concentration of Cd, a highly toxic and mobile heavy metal, in contaminated water. At concentrations of 1.1 mg Cd per L, flax and grape waste were found superior in removing Cd compared with a granular activated carbon used in water treatment, which is both more expensive and entails greater CO emissions in its production. At a pH representative of mine effluents, where Cd presents its greatest mobility and risk as a pollutant, grape and flax waste showed capacity for effective bulk water treatment due to rapid removal kinetics and moderate adsorption properties: reaching equilibrium within 183 and 8 min - adsorption capacities were determined as 3.99 and 3.36 mg Cd per g, respectively. The capacity to clean contaminated effluents was not correlated with the surface area of the biosorbents. Surface chemistry analysis indicated that Cd removal is associated with exchange with Ca, and chemisorption involving CdCO, CdS and CdO groups. This work indicates that some AWBs can be directly ( without pre-treatment or modification) used in bulk to remediate effluents contaminated with heavy metals, without requiring further cost or energy input, making them potentially suitable for low-cost treatment of persistent ( mine drainage) or acute ( spillages) discharges in rural and other areas.
农业生产会产生可再利用以改善环境质量的废弃物。这项研究首次探讨了利用葡萄、小麦、大麦和亚麻生产过程中大量未改性的农业废弃物和副产品（AWB），来降低受污染水中镉（一种剧毒且易迁移的重金属）的浓度。在镉浓度为每升1.1毫克的情况下，发现亚麻和葡萄废弃物在去除镉方面优于用于水处理的粒状活性炭，后者不仅成本更高，而且在生产过程中会产生更多的碳排放。在代表矿井废水的pH值条件下，镉作为污染物的迁移性和风险最大，葡萄和亚麻废弃物由于去除动力学迅速和吸附性能适中，显示出对大量水体进行有效处理的能力：分别在183分钟和8分钟内达到平衡，吸附容量分别确定为每克3.99毫克和3.36毫克镉。清洁受污染废水的能力与生物吸附剂的表面积无关。表面化学分析表明，镉的去除与钙的交换以及涉及碳酸镉、硫化镉和氧化镉基团的化学吸附有关。这项研究表明，一些农业废弃物和副产品可以直接（无需预处理或改性）大量用于修复受重金属污染的废水，无需进一步的成本或能源投入，这使得它们有可能适用于农村和其他地区对持久性（矿井排水）或急性（泄漏）排放进行低成本处理。
