A Comparative Study on Sorption Characteristics by Corn Stalk Pith Using Green Modification with Different Polycarboxylic Acids

Abstract

In this study, an efficient and economical modification with low chemical concentration process was used for preparing biosorbent. Corn stalk pith (CP) was esterified with different polycarboxylic (tartaric, citric, and malic) acids, and then the resultant modified products were applied as sorbents to remove methylene blue (MB) via sorption. Compared with the raw materials, the esterification led to some variation in the specific surface area, pore volume and structure, which thereby affected the sorption efficacy of MB. The pseudo-second-order kinetic model and the Langmuir model well described the MB sorption for all modified CPs. Following modification, sorption capacity increased by 290.1 % for tartaric acid modified-CP, 759.0 % for citric acid modified-CP and 658.2 % for malic acid modified-CP, and the maximum MB sorption were 208.3, 458.7 and 404.9 mg/g, respectively. The mechanisms of MB sorption via modified CP involve electrostatic interaction, π-π interaction, and hydrogen bonds interaction. The substantial enhancement on MB sorption by the CP esterified with polycarboxylic acids provides a novel means for dyes removal from wastewater.