提升生物质焦液相吸附容量的焦改性方法研究进展

Progress on the modification methods of bio-char for enhanced adsorption of pollutants from aqueous solution

生物质焦是生物质热化学转化过程中的副产品,是一种潜在的物理吸附剂,能够用作水处理吸附多种污染物。通过不同的改性方式,能够改变生物质焦的物理结构和化学特性,从而改变其对污染物的吸附脱除能力。本文在详细分析液相溶液吸附影响因素的基础上,总结了针对不同种类污染物,提升其吸附容量的有效生物质焦改性方法,包含热处理、添加试剂扩孔、超声波处理以及化学修饰和生物辅助等手段,并认为除孔隙特性外,生物质焦表面含氧官能团的化学特性同样对吸附起重要作用,如酸处理可增加焦表面酸性含氧官能团,并因阳离子交换作用而利于吸附金属离子;碱处理的焦表面因离域π电子密度提高,色散力增强,从而有利于吸附脱除酚酞、染料等有机污染物;而负载原子和化合物的焦能同时提升其对有机和金属污染物的脱除能力。此外,发现微生物作用下的生物吸附有助于脱除难降解的苯酚。该文为提升生物质焦吸附容量的改性方法选择提供了有效思路。

The bio-char is one of the by-products from biomass pyrolysis, and it is a potential adsorbent for pollutants removal in aqueous solution. Through different modification methods, the physical/chemical properties of the bio-char could be changed. The adsorption capacity of pollutants would also be changed by the modification. Based on the analysis of the adsorption factors in aqueous solution, the enhanced absorption methods were proposed including heat treatment, reagent added for enlarge the pore volume, ultrasonic treatment, chemical modification and biological treatment. It was found that the surface oxygen functional groups of the bio-char played an important role in adsorption besides the pore structures. The surface acidity of the oxygen functional groups on bio-char would be increased after acid treatment. The adsorption capacity of metal ions would also be increased onto bio-char because of the cation exchange reaction. The delocalized π electron density would be increased by alkali treatment, which was helpful for phenolphthalein, dyes and other organic pollutants removal The removal ability of organic and metal contaminants would be improved by the load atoms and compounds of bio-char. In addition, biological adsorption was found to be helpful for phenol removal. This paper provided effective ideas for the enhance adsorption of bio-char.