Application of aspartame modified magnetic dialdehyde starch nano-composite as photocatalyst for the removal of Phenolphthalein from aqueous solution and modeling by response surface methodology

Industrial activities generate large volume of wastewater containing hazardous inorganic or organic species [1]. Some of these contaminants due to their natural toxicity, carcinogenic or mutagenic property and also their high bioaccumulation efficiency received special attentioneven at very low concentrations The adsorption technique is one of the most effective methods for removal of contaminants, in terms of cost, flexibility, simplicity of design, ease of operation, insensitivity to toxic pollutants and better removal efficiency. Furthermore, it does not result in the formation of harmful substances like most of the other techniques. In order to improve performance of adsorption such as sorption capacity, increased mechanical strength, and resistance to chemicals and enhance the separation rate, the design and exploration of novel adsorbents are still necessary. In the last decade, Fe-containing compounds in the nanometric scale have been used [2]. The advantage of using these materials is the very high surface area available for the catalytic activity. To ensure a maximum yield, minimum time, energy and materials consumption in reactions, the optimization of the variables involved in the process to select the best conditions is needed. One of the efficient statistical techniques which is used excessively in optimization procedures is Plackett–Burman designs (PBDs) [3]. But the optimum value for each parameter cannot be found. Central composite design (CCD) is frequently used to optimize the significant factors for analytical procedure using k factor experiments.In this study, the novel magnetic nano-composite has been successfully synthesized by covalently linking dialdehyde starch and amine functionalized Fe3O4 nanoparticle, and modifying with aspartame functional group. Scanning electron microscopy and infrared spectroscopy techniques were used to characterize the composite. The photocatalytic adsorption behaviors of the composite in Phenolphthalein removal, which is widely used as an acidic-basic indicator, from aqueous solutin were evaluated by batch equilibrium experiments using response surface methodology and employing a central composite design Experimental. The influence of different parameters on the removal of Phenolphthalein was examined. pH, contact time, and sorbent dosage had a significant impact on Phenolphthalein removal. Under the optimized conditions, the maximum sorption capacity for Phenolphthalein was found to be 97.98%. The isotherm models of Freundlich, Langmuir and Dubinin –Radushkevich, were used for the equilibrium data analysis. The kinetic data were analyzed using the pseudo-first-order, and pseudo-second-order models.