Lignocellulosic derivative and chitosan bioadsorbent: Synthesis, characterization, and performance in chromium adsorption

Abstract

Environmental pollution with heavy metals, especially with hexavalent chromium, is a serious problem worldwide. Therefore, in this study, the synthesis, characterization, and application of a heavy metal bioadsorbent, CMCCHDIC, were carried out. Carboxymethylcellulose (CMC) was synthesized from corn stover and reacted with chitosan (CH) using N,N′-diisopropylcarbodiimide (DIC) as a coupling reagent to obtain CMCCHDIC. CMC and CMCCHDIC were characterized by granulometric distribution of microparticles, scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry, and nuclear magnetic resonance. The ideal conditions for CMCCHDIC adsorption were determined, and 180 min of contact time, pH 2.5, and 293 K were observed to yield the best adsorption capacity. An increase in the adsorption capacity of CMCQDIC (qe = 115.78 ± 0.17 mg∙g−1) to 81.5% relative to that of pure CH (qe = 63.78 ± 0.48 mg∙g−1) was observed, and the reduction of solubility in acidic media comparing with CH, which favors the application of the bioadsorbent synthetized.