Resource utilization of typical biomass wastes as biochars in removing plasticizer diethyl phthalate from water: characterization and adsorption mechanisms

Plastic pollution as a global environmental issue has become a research hotspot, among which the removal of inherent plasticizer (e.g., phthalic acid esters, PAEs) received increasing attention. However, the effects of biochars derived from different feedstocks on the adsorption of PAEs are poorly understood. Thus, the characteristics of biochars derived from six largely produced biomass wastes in China at 400 degrees C, as well as their performance in adsorption of diethyl phthalate (DEP), one of frequently detected PAEs in aqueous environment, were investigated. The results indicated that the variation in feedstock type showed significant changes in the properties (e.g., porosity, specific surface area, surface functional groups) of biochars, which affected DEP adsorption and desorption. Pseudosecond order and Freundlich models fitted the adsorption data well, and adsorption mechanisms mainly included hydrophobic effect, followed by micropore filling, hydrogen bonding, and pi-pi EDA interactions. Adsorption thermodynamics revealed that the adsorption was a spontaneous and exothermic the adsorption capacities of DEP on these biochars slightly decreased with the increasing pH but increased with the increasing ionic strength. Among these biochars, the giant reed biochar with relatively higher DEP adsorption and low desorption exhibited the great efficiency for DEP removal as an environment-friendly sorbent. These results highlighted the significant roles of micropore filling and hydrogen bond in determining adsorption capacity of designed biochars prepared from selecting suitable agricultural straws and wetland plant waste to typical plasticizer. The findings are useful for producing designed biochars from different biomass wastes for plasticizer pollution control. (c) Higher Education Press 2023

Automated summary

Plastic pollution is a global environmental issue, and the removal of inherent plasticizer has gained significant attention. This study investigated the characteristics and performance of biochars derived from six different biomass wastes in China for the adsorption of diethyl phthalate (DEP), a frequently detected plasticizer in water. The results showed that the properties of biochars, such as porosity, specific surface area, and surface functional groups, varied with the feedstock type, which influenced the adsorption and desorption of DEP. The adsorption mechanisms involved hydrophobic effect, micropore filling, hydrogen bonding, and pi-pi EDA interactions. Among the biochars, giant reed biochar exhibited high DEP adsorption capacity and low desorption, making it an efficient and environmentally friendly sorbent for DEP removal. These findings are important for the production of designed biochars from different biomass wastes to control plasticizer pollution.