藻基生物炭的氧化改性及其吸附砷微观机制的量化分析
- Oxidative modification of algal-based biochar and its microscopic mechanism of adsorption of arsenic
- 基金项目：国家自然科学基金(No.52070137); 苏州市科技计划项目(2022SS18, SS202107)
- 吴兵党
- 苏州科技大学环境科学与工程学院;苏州市海绵城市技术重点实验室;苏州高新水质净化有限公司
- 摘要：资源化藻炭材料因孔隙结构不发达和表面活性位点少而吸附砷性能不佳。以螺旋藻为炭源(HLX)、K2FeO4为活化剂制备了改性藻炭材料(HLX-Fe),研究了其对As(III)和As(V)的吸附性能和微观机制。结果表明,高铁酸钾活化的HLX-Fe,Fe负载量达30%,孔径主要集中在1~2 nm,具有丰富的表面缺陷(ID/IG=0.79)和-OH和-COOH等官能团,比表面积较HLX提升了126倍,等电点由HLX的3.15提高至5.55,表明高铁酸钾改性改善了藻炭材料表面结构,更利于其吸附砷酸盐。吸附性能实验结果显示,HLX-Fe对砷酸盐的最大吸附容量为196.2 mg/g (As(III))和 188.6 mg/g (As(V)),具有宽pH (2-10)适应性和良好的抗共存离子(CO32-、SiO32-、PO42-、NO3-、Cl-)和有机物(HA)性能,且经5次脱附-吸附材料对As(III)的吸附量仅下降13.4%,且可通过磁分离进行吸附剂的回收。通过XPS表征、Zeta电位和官能团滴定探究和量化了吸附机理,发现发达的孔隙结构和表面丰富的缺陷为砷酸盐的吸附提供了大量的活性吸附位点,表面官能团络合是最主要的吸附途径,占比为83.41%。该研究为废弃生物质的资源化以及砷污染治理提供了参考。
- Abstract：Due to the poor pore structure and few surface-active sites, the adsorption performance of the regenerative algal carbon was not outstanding. Here, the adsorption properties and microscopic mechanism of modified algal carbon (HLX-Fe) for As(III) and As(V) were studied, HLX-Fe was prepared with Spirulina as carbon source (HLX) and K2FeO4 as activator. The results show that HLX-Fe activated by potassium ferrate has a Fe loading capacity of 30%, pore size of 1~2 nm, abundant surface defects (ID/IG=0.79) and functional groups such as OH and -COOH. The specific surface area is 126 times higher than HLX, and the isoelectric point is increased from 3.15 to 5.55. The results showed that the modification of potassium ferrate improved the surface structure of algal carbon and was more beneficial to its adsorption of arsenate. The adsorption performance experiment results showed that the maximum adsorption capacity of HLX-Fe for arsenate was 196.2 mg/g (As(III)) and 188.6 mg/g (As(V)). It has a wide pH (2-10) adaptability and good resistance to coexisting ions (CO32-, SiO32-, PO43-, NO3-, Cl-) and organic matter (HA) properties, and the adsorption capacity of As(III) is only reduced by 13.4% after five desorption-adsorption materials, and the adsorbent can be recovered through magnetic separation. Through XPS characterization, Zeta potential and functional group titration, the adsorption mechanism was explored and quantified. It was found that developed pore structure and abundant surface defects provided a large number of active adsorption sites for arsenate adsorption, and surface functional group complexation was the most important adsorption pathway, accounting for 83.41%. This study shed light on the recycling of waste biomass and the treatment of arsenic pollution.
