Combination process for dye removal based on photocatalyst and adsorption using low cost waste material adsorbent

Abstract This study investigated the removal of methylene blue and methyl orange dyes from aqueous solutions containing these dyes. The process of wastewater treatment involved a combination of adsorption processes performed using UV/H 2 O 2 /TiO 2 and fly‐ash adsorbent prepared from sunflower seed pulp. In this study, first the effect of UV/H 2 O 2 /TiO 2 process parameters including initial dye concentration (10–30 mg/L), UV lamp power (0–30 W), hydrogen peroxide concentration (100–500 mg/L), and titanium dioxide concentration (10–50 mg/L) were investigated (under a process time of 75 min and adsorbent concentration of 2 g/L). In optimal conditions, the percentage of removal of methylene blue and methyl orange dyes were 96.43% and 83.60%, respectively. After the optimization of the parameters of UV/H 2 O 2 /TiO 2 process, the processing time and adsorbent concentration were investigated. The results indicated that when performing the process under the process time of 150 min and the adsorbent concentration of 2 g/L, the removal of methylene blue dye exceeded 99%. In addition, the removal of methyl orange dye under the process time of 300 min and the adsorbent concentration of 10 g/L exceeded 99%. At the end of the study, an assessment was carried out using quasifirst‐order and quasisecond‐order kinetic models and the results indicated that both kinetic models had a high level of accuracy for modeling the adsorption of methylene blue and methyl orange dyes on fly‐ash adsorbents prepared from sunflower seed pulp.