Effective adsorption of Tartrazine by modified biomaterial from wheat residues

Abstract

The use of adsorbents from wheat residues (WR), wheat cellulose (WC) and wheat cellulose (MWC) treated with Cetyl trimethyl ammonium chloride (CTAC) was studied in the removal of tartrazine in an aqueous solution. The effect of adsorbent dose (15, 25 and 35 mg) and initial concentration (40, 70 and 100 mg/L) was evaluated. WC was obtained by double alkaline extraction, and the modification was performed with CTAC at 25 %w. Adsorption tests were performed following a multifactorial experimental design 33, placing 5 mL of solution in contact with the bioadsorbent for 24 h, at 30 °C and 250 rpm. UV-Vis determined the concentration of tartrazine at 500 nm. FTIR analysis showed that the prepared adsorbents present a diverse structure, with functional groups such as OH, carboxyl, amino and hydrocarbon compounds. Decreasing the adsorbent dose and increasing the initial concentration positively affect the removal efficiency, achieving the removal of 97.65 % with MWC. Adsorption kinetics showed that equilibrium was reached at 480 min when MWC and WC were used. The Freundlich model fitted the adsorption equilibrium data, showing that removal occurs in multilayers due to chemical interactions. CTAC-modified wheat cellulose is a good adsorbent for tartrazine in an aqueous solution.