Hassan Masud, Liu Yanju, Naidu Ravi, Du Jianhua, Qi Fangjie, Donne Scott W, Islam Md Monirul
Global Centre for Environmental Remediation, College of Engineering, Science and Environment, University of Newcastle, Level-1, Advanced Technology Centre (ATC Building), Ring Road, Callaghan, NSW 2308, Australia.
Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE), Callaghan, NSW 2308, Australia.
ACS Omega. 2021 May 31;6(23):15316-15331. doi: 10.1021/acsomega.1c01642. eCollection 2021 Jun 15.
Halloysite nanotubes (HNT) and ball-milled biochar (BC) incorporated biocompatible mesoporous adsorbents (HNT-BC@Alg) were synthesized for adsorption of aqueous heavy-metal ions. HNT-BC@Alg outperformed the BC, HNT, and BC@Alg in removing cadmium (Cd), copper (Cu), nickel (Ni), and lead (Pb). Mesoporous structure (∼7.19 to 7.56 nm) of HNT-BC@Alg 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 CaCl and NaSO 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. HNT-BC@Alg 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 HNT-BC@Alg (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.
合成了包含埃洛石纳米管（HNT）和球磨生物炭（BC）的生物相容性介孔吸附剂（HNT-BC@Alg），用于吸附水溶液中的重金属离子。在去除镉（Cd）、铜（Cu）、镍（Ni）和铅（Pb）方面，HNT-BC@Alg的性能优于BC、HNT和BC@Alg。HNT-BC@Alg形成了介孔结构（约7.19至7.56纳米），含有大量由包封的BC和管状HNT诱导产生的官能团，这使得重金属能够渗透并与吸附剂相互作用。HNT的硅氧烷基团、BC的含氧官能团以及海藻酸盐聚合物的羟基和羧基在重金属离子的吸附中起重要作用。即使在存在0.01/0.001 M的CaCl和NaSO作为背景电解质以及环境相关浓度（200 μg/L）的带电有机分子的情况下，重金属的去除率记录为Pb（约99.97%至99.05%）> Cu（约95.01%至90.53%）> Cd（约92.5%至55.25%）> Ni（约80.85%至50.6%）。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。HNT-BC@Alg具有快速的吸附动力学，并且在短接触时间（约2小时）内具有最大吸附容量。能量色散X射线光谱（EDS）元素映射显示吸附的重金属与Ca、Si和Al共分布。HNT-BC@Alg（吸附重金属后）的表面积、孔体积和孔面积的减小证实了介孔表面（2-18纳米）支持扩散、渗透和相互作用。然而，吸附剂较低范围的介孔直径更适合吸附重金属离子。吸附等温线和动力学与朗缪尔等温线和伪二级动力学模型拟合良好，表明重金属离子通过物理吸附和化学吸附形成单层，包括孔填充、离子交换和静电相互作用。
