An ecologically sustainable specific method using new magnetic alginate-biochar from acorn cups (Quercus coccifera L.) for decolorization of dyes

Abstract

The use of abundant and low-cost adsorbents for the removal of industrial dyes such as methylene blue (MB) and malachite green (MG) from industrial wastewater has been researched. Biochar (BC) prepared from acorn cup as an alternative adsorbent for this aim was studied. A new adsorbent was prepared using alginate-encapsulated acorn cup biochar (BC) and nano-Fe3O4 as a high-performance green absorbent. A batch-type model was used to test the removal of MB and MG from aqueous solutions by magnetic alginate-BC, m-(Alg/BC) nanocomposite as a biosorbent. Investigations were done into how initial dye concentration, adsorbent dosage, contact time, and pH variation affected adsorption removal. Optimum adsorption of MB and MG dye was observed at natural solution pH and 3 g L−1 of adsorbent dosage at 120 min of contact time. Adsorption isotherms were modeled with the Langmuir, Freundlich, Temkin, and D-R adsorption isotherms. The adsorption process is accurately described by the Langmuir isotherm model, yielding an extreme adsorption capacity of 52.63 mg g−1 for MB and 22.88 mg g−1 MG, respectively. The adsorption process followed a pseudo-second-order kinetic model, and thermodynamic studies revealed that it is an endothermic and spontaneous process. m-(Alg/BC) nanocomposite with great dye removal capacity could be used for the adsorption system. Graphical abstract: [Figure not available: see fulltext.]. © 2022, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.