摘要
Halloysite nanotubes (HNT) and ball-milled biochar (BC) incorporated biocompatible mesoporous adsorbents ([email protected]) were synthesized for adsorption of aqueous heavy-metal ions. [email protected] outperformed the BC, HNT, and [email protected] in removing cadmium (Cd), copper (Cu), nickel (Ni), and lead (Pb). Mesoporous structure (∼7.19 to 7.56 nm) of [email protected] was developed containing an abundance of functional groups induced from encapsulated BC and tubular HNT, which allowed heavy metals to infiltrate and interact with the adsorbents. Siloxane groups from HNT, oxygen-containing functional groups from BC, and hydroxyl and carboxyl groups from alginate polymer play a significant role in the adsorption of heavy-metal ions. The removal percentage of heavy metals was recorded as Pb (∼99.97 to 99.05%) > Cu (∼95.01 to 90.53%) > Cd (∼92.5 to 55.25%) > Ni (∼80.85 to 50.6%), even in the presence of 0.01/0.001 M of CaCl2 and Na2SO4 as background electrolytes and charged organic molecule under an environmentally relevant concentration (200 μg/L). The maximum adsorption capacities of Ni, Cd, Cu, and Pb were calculated as 2.85 ± 0.08, 6.96 ± 0.31, 16.87 ± 1.50, and 26.49 ± 2.04 mg/g, respectively. [email protected] has fast sorption kinetics and maximum adsorption capacity within a short contact time (∼2 h). Energy-dispersive X-ray spectroscopy (EDS) elemental mapping exhibited that adsorbed heavy metals co-distributed with Ca, Si, and Al. The reduction of surface area, pore volume, and pore area of [email protected] (after sorption of heavy metals) confirms that mesoporous surface (2–18 nm) supports diffusion, infiltration, and interaction. However, a lower range of mesoporous diameter of the adsorbent is more suitable for the adsorption of heavy-metal ions. The adsorption isotherm and kinetics fitted well with the Langmuir isotherm and the pseudo-second-order kinetic models, demonstrating the monolayer formation of heavy-metal ions through both the physical sorption and chemical sorption, including pore filling, ion exchange, and electrostatic interaction.
摘要译文
合成Halloysite Nanotubes（HNT）和球磨的生物炭（BC）的生物相容性介孔吸附剂（[email pandected]）被合成用于吸附含量的重金属离子。 [电子邮件受保护]表现优于BC，HNT和[电子邮件保护]去除镉（CD），铜（Cu），镍（Ni）和铅（PB）。开发了[电子邮件保护]的中孔结构（〜7.19至7.56nm），其含有从包封的BC和管状HNT诱导的官能团，其允许重金属渗透并与吸附剂相互作用。来自HNT，来自BC的含氧官能团的硅氧烷基团，来自藻酸盐聚合物的羟基和羧基以及在重金属离子的吸附中起着重要作用。将重金属的去除率记录为Pb（〜99.97至99.05％）> Cd（〜92.01至90.53％）> Cd（〜92.5至55.25％）> Ni（~80.85至50.6％），即使存在0.01 / 0.001M CaCl 2和Na 2 SO 4作为背景电解质和带电有机分子在环境相关浓度（200μg/ L）。 Ni，Cd，Cu和Pb的最大吸附容量分别计算为2.85±0.08,6.96±0.31,16.87±1.50和26.49±2.04 mg / g。 [电子邮件受保护]在短接触时间内具有快速吸附动力学和最大吸附容量（〜2小时）。能量分散X射线光谱（EDS）元素映射表现出与Ca，Si和Al共分配的吸附重金属。 [电子邮件保护]（重金属吸附后）的表面积，孔体积和孔面积的减少证实了介孔表面（2-18nm）支持扩散，渗透和相互作用。然而，吸附剂的较低范围的介孔直径更适合于吸附重金属离子。吸附等温线和动力学与Langmuir等温线和伪二阶动力学模型很好，证明了通过物理吸附和化学吸附的单层形成重金属离子，包括孔隙填充，离子交换和静电相互作用。
Masud Hassan;Yanju Liu;Ravi Naidu;Jianhua Du;Fangjie Qi;Scott W. Donne;Md Monirul Islam. Mesoporous Biopolymer Architecture Enhanced the Adsorption and Selectivity of Aqueous Heavy-Metal Ions[J]. ACS Omega, 2021,6(23): 15316-15331