Simultaneous adsorption of three anionic dyes at neutral pH from their individual and multi-component systems on a CTAB modified Pennisetum glaucum based carbon nanotube green composite: Adsorption mechanism and process optimization by Box-Behnken design model

In this study, an efficient, cost-effective, and environmentally friendly cetyltrimethylammonium bromide (CTAB) surfactant modified Pennisetum glaucum (RM) based composite containing 0.5% functionalized carbon nanotube (CNT) has been developed. The main aim of this study was to assess and optimize the synthesized adsorbent used for the removal of Reactive Red 35 (RR), Coomassie Brilliant Blue R-250 (BB), and Eriochrome Black-T (EBT) dyes in their single, binary, and ternary solutions by employing the Box Behnken Design (BBD) under Response Surface Methodology (RSM). According to the analysis of variance (ANOVA), the proposed quadratic model was significant, with a good correlation between the experimental and predicted data of the desired response, and it can be used to navigate the design space. Furthermore, the batch adsorption experiments of anionic dyes were conducted to discuss the bio-sorption kinetics, thermodynamics, isotherms, and possible adsorption mechanisms involved in single and multi-component systems were accordingly proposed. The equilibrium experimental data was best fitted to the monolayer Langmuir adsorption isotherm model, giving a maximum adsorption capacity of 210.97, 259.07, and 289.85 mgg 1 for RR, BB, and EBT dyes, respectively, in individual component sys-tems, at neutral pH conditions, and a pseudo-2nd-order kinetic model best followed the kinetic data. The modified Langmuir model was used to study the interactions among the dye molecules in multi-component systems, and the observed results indicate the synergistic and competitive behaviour of dyes. A regeneration study of the exhausted bio-composite evaluated the renewal efficiency. This requires sim-ple processing methods and little expense than other adsorbents fabricated from costly materials. Ultimately, the CTAB treated Pennisetum glaucum based CNT composite could be adopted as an efficient, cost-effective, and environmentally benign green biosorbent. (C) 2022 Elsevier B.V. All rights reserved.