PH dependence of glyphosate adsorption from aqueous solution using a cationic cellulose microfibers (cCMF) biosorbent

Abstract

Currently, the agricultural sector is responsible for the contamination of groundwater and springs due to the excessive use of pesticides, which represents a risk to human and environmental health. Among pesticides, glyphosate is the most used herbicide to increase agricultural production, however, it can cause intoxication in humans and has been classified as a potentially carcinogenic agent. Alternatives for removing these contaminants from water have been studied and discussed, including biosorption, a physical-chemical process that removes substances from solutions using a natural and renewable material. In this sense, this work studied the process to obtain cationic cellulose microfibers (cCMF) from sugarcane bagasse residue, by cellulose isolation followed by cationization reaction with Girard T reagent to promote a new adsorbent for glyphosate removal from water. It was observed that cCMF structure maintains the fibrillar morphology after the microfiber production (1.375mmolg-1 oxidation degree). Results of zero charge of cCMF microfibers showed an isoelectric point pH = 5.4 ± 0.016 and the highest adsorption capacity was reached at pH 14 (59.21%), showing a clear pH dependence on the adsorption process. Thereby, the cCMF can be produced from sugarcane bagasse residue being applied as a potential biomaterial for removing organic compounds from water.