Cellulose adsorbent produced from the processing waste of brewer's spent grain for efficient removal of Mn and Pb from contaminated water

Removal of heavy metals from drinking water is of high importance to human health. This study reports the fabrication of a novel cellulose adsorbent from a secondary waste ma-terial, i.e., a fiber-rich product (FP) from brewer's spent grain, for Pb and Mn removal from water. FP was sequentially treated by diluted acid, alkali, and bleach to produce purified cellulose fibers, which were then modified by 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) oxidation. The adsorption data fitted the Langmuir isotherm and the maximum adsorption capacity of the adsorbent was determined to be 272.5 mg/g for Pb (II) and 52.9 mg/g for Mn (II) at pH 6.5. Kinetic studies showed that the adsorption process followed the pseudo-second-order rate model and nearly completed in 15 min. The performance of the adsorbent in removing Pb and Mn from contaminated tap water was efficient with 87.4% of Pb and 83.9% of Mn. This study provides a novel insight into the fabrication of low-cost and high-capacity cellulose adsorbents from a waste material, then demon-strates its application for water purification. Meanwhile, it allows the integrated utiliza-tion of brewer's spent grain, which supports the sustainable resource management and circular economy development.(c) 2022 Institution of Chemical Engineers. Published by Elsevier Ltd. All rights reserved.