Key Laboratory of Integrated Regulation and Resources Development on Shallow Lakes of Ministry of Education, College of Environment, Hohai University, Nanjing 210098, China.
Key Laboratory of Integrated Regulation and Resources Development on Shallow Lakes of Ministry of Education, College of Environment, Hohai University, Nanjing 210098, China.
Ecotoxicol Environ Saf. 2021 Dec 1;225:112750. doi: 10.1016/j.ecoenv.2021.112750. Epub 2021 Sep 13.
This study investigated the adsorption characterizations and mechanisms of lead (Pb) on biochar-derived microalgae residue (MB) produced at different pyrolytic temperatures. Six different MB samples were prepared from Chlorella sp. (CB) and Spirulina sp. (SB) in the temperature range of 200-600 ℃, and microalgae residue power (MP) was used as a control. The effect of pH, adsorption kinetics and isotherms were studied for the different MBs, and a chemical analysis of Pb-loaded MP and MB was performed by SEM-EDS, XRD, XPS, FTIR, and Boehm titration. The results showed that Pb adsorption on MP and MB was a monolayer chemical adsorption process. Precipitation with minerals, metal ion exchange, oxygen/nitrogen-containing functional groups (OFGs/NFGs), and coordination of Pb with π electrons jointly contributed to Pb adsorption on MP and MB. More specifically, the contribution of each mechanism depended on the pyrolytic temperature. The contribution of surface complexation and ion exchange decreased with increasing pyrolytic temperature due to the loss of OFGs/NFGs and decreasing metal ion content, while the contribution of precipitation and Pb-π interaction significantly increased. Overall, precipitation with minerals and ion exchange dominated Pb adsorption on MP and MB, which accounted for 65.20-74.40% of the total adsorption capacity. Surface precipitation contributed to a maximum adsorption capacity for high-temperature CB and SB (600 ℃) of up to 131.41 mg/g and 154.56 mg/g, respectively. In conclusion, MB adsorbents are a promising material for the remediation of heavy metal-bearing aquatic environments.
本研究考察了不同热解温度下生物炭衍生微藻残渣（MB）对铅（Pb）的吸附特性和机制。在 200-600℃温度范围内，用小球藻（CB）和螺旋藻（SB）制备了 6 种不同的 MB 样品，并使用微藻残渣粉（MP）作为对照。研究了不同 MB 的 pH 值、吸附动力学和等温线的影响，并通过 SEM-EDS、XRD、XPS、FTIR 和 Boehm 滴定对负载 Pb 的 MP 和 MB 进行了化学分析。结果表明，Pb 在 MP 和 MB 上的吸附是单层化学吸附过程。矿物沉淀、金属离子交换、含氧/含氮官能团（OFGs/NFGs）和 Pb 与π电子的配位共同促进了 MP 和 MB 对 Pb 的吸附。更具体地说，每种机制的贡献取决于热解温度。由于 OFGs/NFGs 的损失和金属离子含量的降低，表面络合和离子交换的贡献随热解温度的升高而降低，而沉淀和 Pb-π 相互作用的贡献显著增加。总体而言，矿物沉淀和离子交换主导了 MP 和 MB 对 Pb 的吸附，占总吸附容量的 65.20-74.40%。表面沉淀对高温 CB 和 SB（600℃）的最大吸附容量分别高达 131.41 mg/g 和 154.56 mg/g。综上所述，MB 吸附剂是修复重金属污染水生环境的一种很有前途的材料。
