Soini Steven A, Feliciano Sofia M, Duersch Bobby G, Merk Vivian M
Department of Chemistry and Biochemistry, Department of Ocean and Mechanical Engineering, Florida Atlantic University Boca Raton FL 33431 USA
RSC Sustain. 2024 Jan 15;2(3):626-634. doi: 10.1039/d3su00326d. eCollection 2024 Mar 6.
Harmful levels of environmental contaminants, such as arsenic (As), persist readily in the environment, threatening safe drinking water supplies in many parts of the world. In this paper, we present a straightforward and cost-effective filtration technology for the removal of arsenate from potable water. Biocomposite filters comprised of nanocrystalline iron oxides or oxyhydroxides mineralized within lignocellulose scaffolds constitute a promising low cost, low-tech avenue for the removal of these contaminants. Two types of iron oxide mineral phases, 2-line ferrihydrite (Fh) and magnetite (Mt), were synthesized within highly porous balsa wood using an environmentally benign modification process and studied in view of their effective removal of As from contaminated water. The mineral deposition pattern, minerology, as well as crystallinity, were assessed using scanning electron microscopy, transmission electron microscopy, micro-computed X-ray tomography, confocal Raman microscopy, infrared spectroscopy, and X-ray powder diffraction. Our results indicate a preferential distribution of the Fh mineral phase within the micro-porous cell wall and radial parenchyma cells of rays, while Mt is formed primarily at the cell wall/lumen interface of vessels and fibers. Water samples of known As concentrations were subjected to composite filters in batch incubation and gravity-driven flow-through adsorption tests. Eluents were analyzed using microwave plasma optical emission spectroscopy (MP-AES) and inductively coupled plasma mass spectrometry (ICP-MS). By subjecting the filters to a flow of contaminated water, the time for As uptake was reduced to minutes rather than hours, while immobilizing the same amount of As. The retention of As within the composite filter was further confirmed through energy-dispersive X-ray mappings. Apart from addressing dangerously high levels of arsenate in potable water, these versatile iron oxide lignocellulosic filters harbor tremendous potential for addressing current and emerging environmental contaminants that are known to adsorb on iron oxide mineral phases, such as phosphate, polycyclic aromatic hydrocarbons or heavy metals.
有害水平的环境污染物，如砷（As），在环境中很容易持续存在，威胁着世界许多地区的安全饮用水供应。在本文中，我们提出了一种简单且经济高效的过滤技术，用于从饮用水中去除砷酸盐。由木质纤维素支架中矿化的纳米晶氧化铁或羟基氧化物组成的生物复合过滤器，为去除这些污染物提供了一种有前景的低成本、低技术途径。使用环境友好的改性工艺在高度多孔的轻木中合成了两种类型的氧化铁矿物相，即二线水铁矿（Fh）和磁铁矿（Mt），并对它们从污染水中有效去除砷的情况进行了研究。使用扫描电子显微镜、透射电子显微镜、微型计算机X射线断层扫描、共焦拉曼显微镜、红外光谱和X射线粉末衍射对矿物沉积模式、矿物学以及结晶度进行了评估。我们的结果表明，Fh矿物相优先分布在射线的微孔细胞壁和径向薄壁细胞内，而Mt主要在导管和纤维的细胞壁/管腔界面形成。将已知砷浓度的水样在批量培养和重力驱动的流通吸附试验中通过复合过滤器。使用微波等离子体发射光谱法（MP-AES）和电感耦合等离子体质谱法（ICP-MS）对洗脱液进行分析。通过使过滤器接触污染水流，砷的吸收时间从数小时缩短至数分钟，同时固定相同量的砷。通过能量色散X射线映射进一步证实了砷在复合过滤器中的保留情况。除了解决饮用水中危险的高砷酸盐水平外，这些多功能的氧化铁木质纤维素过滤器在解决目前已知吸附在氧化铁矿物相上的现有和新出现的环境污染物方面具有巨大潜力，如磷酸盐、多环芳烃或重金属。
