Capability of new Biochar/ZnO/SnO2 nanocomposite with high ability in removal of acid orange 7 solution

The aim of this study was to investigate the removal of acid orange 7 from aqueous solution using a new triple nanocomposite biochar/ZnO/SnO2. In this experimental study, weight percentages of ZnO, weight percentages of SnO2, pH, dye concentration and nanocomposite dosage as effective parameters on removal of acid orange 7 using one factorial method were analyzed. The maximum dye removal efficiency of 96.92% obtained at optimum conditions, 20% weight ratio for ZnO, 5% weight ratio for SnO2, pH = 7.1, 250 ppm dye concentration, 0.5 g/L nanocomposite dose after 60 minute. One of the highlights of the nanocomposite was its high power to remove dyes in a very short time. As after 2 minutes of testing, most of the dye (about 86%) was removed. It was also observed that the nanocomposite had the ability to reduce COD by 77.27% and TOC by 66.6% after 2 hours. Also, nanocomposite was reused until the fourth time, when the efficiency reduction for the first to fourth times was less than 10%. According to the results, the kinetics of the reactions for the nanocomposite were in accordance with the double exponential model and the Langmuir isotherm model was the most consistent with the observed data. Also, according to the thermodynamic studies, the dye adsorption on the surface of the nanocomposite was physical.