Amino-functionalized cellulose fibers recovered from newspaper waste for efficient adsorption of crystal violet: Optimization using central composite design

Abstract

In this work, the adsorption of crystal violet (CV) dye by amino-functionalized cellulose fibers recovered from newspaper waste (NH2-RCF) was studied for the first time. Characterization of the prepared adsorbent was performed by FE-SEM, EDS, FTIR, and BET techniques. Adsorption tests were carried out considering the desired range of influencing factors in adsorption, including dye concentration, pH, adsorbent dose and contact time at room temperature. The response surface methodology (RSM) was selected to study the effect of interaction independent input variables and a dependent output response variable (crystal violet removal efficiency). The results including p-value (2.2 × 10−16), high F-value (560.633), multi. R2 (0.9929), adj. R2 (0.9882) and absence of significance of the model's lack-of fit (0.147) showed that the diminished second order- model is very significant for the elimination of crystal violet dye by the adsorbent. The most removal efficiency of crystal violet dye was found to be 95.1 %, under optimal operational parameters including: adsorbent cycle rate of 0.125 g L−1, pH equal to 9, contact time 92.5 min, and CV concentration of 14 mg L−1. In addition, the results indicated that the pseudo second order kinetic model is the most suitable model for dye adsorption on cellulose adsorbent, and the adsorption behavior of crystal violet dye on NH2-RCF follows the Freundlich model (R2 =0.9955). The negative values of ΔG° at all temperatures exhibited that the spontaneously adsorbed process of crystal violet onto NH2-RCF. In addition, the capacity adsorption and the gradually decreasing in negative values of ΔG° with increasing temperature, implied that the adsorption of crystal violet onto NH2-RCF made more favorable at higher temperature. Collectively, the results showed that the adsorbent created from waste newspaper is an efficient and cheap method to remove crystal violet from aqueous solutions.