Nonlinear regression analysis and response surface modeling of Cr (VI) removal from synthetic wastewater by an agro-waste Cocos Nucifera: Box-Behnken Design(BBD)

Kumari, Binu and Tiwary, Rajani Kant and Singh, Krishna Murari Prasad (2020) Nonlinear regression analysis and response surface modeling of Cr (VI) removal from synthetic wastewater by an agro-waste Cocos Nucifera: Box-Behnken Design(BBD). INTERNATIONAL JOURNAL OF PHYTOREMEDIATION.

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Abstract

In this study mixture of coconut shell and coir was used for Cr (VI) removal from synthetic wastewater and statistical tool Response Surface Modeling (RSM) was applied to optimize process parameters. The solution pH (2–6), reaction time (20–100 minutes) and adsorbent quantity (0.03–0.2 g) was optimized to find the maximum response of Cr (VI) removal using statistical Box-Behnken design (BBD) software. The equilibrium data obtained by the batch experiment were analyzed by ANOVA and found fitted in a second-order polynomial equation through multiple regression analysis. The optimum value of pH, adsorbent quantity and reaction time for 99% of Cr(VI) was found as 2, 0.1 g and 100 minutes, respectively. By using non-linear regression method it was found that Freundlich isotherm and Pseudo-second-order kinetic with high correlation coefficient (R2 ), low Chisquare (v2 ) and root mean squares errors (RMSE), best describe the adsorption of Cr (VI) on mixture of coconut shell and coir (MCSC) surface. Positive enthalpy (DH�) and negative Gibbs free energy (DGo ) values confirm the endothermic and spontaneous nature of adsorption process. Pre and post adsorption phenomenon was confirmed by characterization of adsorbent using AFM, FTIR, SEM, and EDX analysis. The adsorbent MCSC has regenerative property and can be reused 3–4 times after treating with alkaline medium (0.2 N NaOH) and offered more than 60% removal of Cr (VI) at the fourth cycle. It can be inferred based on this study that MCSC is an effective adsorbent for Cr (VI) removal and can be used on an industrial scale for social and environmental benefit

Item Type:	Article
Uncontrolled Keywords:	Chromium (VI); adsorption; kinetics; SEM; AFM; RSM; mixture of coconut shell and coir (MCSC); error function
Subjects:	Enviornmental Management
Divisions:	UNSPECIFIED
Depositing User:	Mr. B. R. Panduranga
Date Deposited:	22 Dec 2020 05:16
Last Modified:	22 Dec 2020 05:16
URI:	http://cimfr.csircentral.net/id/eprint/2288

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