The efficient removal of the hazardous azo dye Acid Orange 7 from water using modified biochar from Pea-peels
Mohamed A. El-Nemr, Nabil Abdelmonem, Ibrahim Ismail, Safaa Ragab, Ahmed El Nemr
Abstract
ABSTRACT In this study, we developed modified biochars and assessed its use for enhancing the adsorption capacity of Acid Orange 7 (AO7) dye. The removal of AO7 dye using unmodified (Pea-B) and modified (Pea- BO-NH 2 and Pea-BO-TETA) biochars derived from the pea Pisum sativum peels were investigated at room temperature using batch adsorption method. The adsorption behavior of biochars toward AO7 dye was studied using different parameters such as dye concentrations, biochar dosage, contact time, and pH. The results reveal that the optimum conditions for the maximum adsorption of AO7 dye are at pH 2 and contact time 3 h. The adsorption capacity at equilibrium (q e ) of the modified biochar was significantly enhanced from 78.18 to 523.12 mg g –1 . Pea-BO-TETA biochar had the largest adsorption capacity (523.12 mg g –1 ) at initial concentration 300 mg L –1 and dosage 0.50 g L –1 . The percentage removal of AO7 dye reached 99% for Pea-BO-NH 2 , 98% for Pea-BO-TETA, and 96% for Pea-B biochars. The structure of the prepared Pea-peel biochars was characterized by Brunauer–Emmett–Teller and Barrett–Joyner–Halenda methods, scanning electron microscopy, Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis and energy-dispersive X-ray spectroscopy (EDAX) analyses. The enhanced of AO7 dye adsorption by modified biochars could be attributed to the increasing surface NH 2 group content which was confirmed by FTIR spectra and EDAX analysis. The results obtained from batch experiments were analyzed by various isotherm models and the error function equations were applied to find the best-fit isotherm model. Freundlich model reported the best fit for the experimental data. The experiment data was primarily obeyed by pseudo-second-order rather than the other studied kinetic models.