Efficient Removal of 2,4-Dichlorophenoxyacetic Acid from Aqueous Medium Using Polydopamine/Polyacrylamide Co-deposited Magnetic Sporopollenin and Optimization with Response Surface Methodology Approach

In this study, a novel binary grafted polydopamine/polyacrylamide onto magnetic sporopollenin (PDA/PAAm@Fe3O4@SP) was synthesized in one step polymerization strategy to investigate its removal performance of 2,4-dichlorophenoxyacetic acid (2,4-D). The response surface methodology (RSM) was applied to evaluate the effects of the process factors including pH (2–8), adsorbent concentration (0.5-2 g/L), initial 2,4-D concentration (Co) (20–80 mg/L), and contact time (30–180 min) for the 2,4-D removal performance. The central composite design (CCD) through RSM was utilized to design the experiments as well as to optimize and model the 2,4-D adsorption process. The ANOVA results clearly shows that the quadratic model (p < 0.0001) was sufficient to the best predicting of the removal performance of 2,4-D (R2 = 0.99). The optimum conditions for the maximum 2,4-D removal (88.31%) was achieved at pH of 3.51, adsorbent concentration of 0.75 g/L, Co of 52.85 mg/L, and contact time of 148.53 min. The adsorption kinetic was represented by both Weber-Morris (R2 = 0.99) and pseudo-second-order models (R2 = 0.99). The isotherm for 2,4-D completely fitted the Dubinin-Radushkevich (D-R) and Langmuir models with R2 values of 0.98. The obtained outcomes indicated that the prepared material may be utilized as an alternative adsorbent for the removal of 2,4-D from waterbodies and the RSM method can be utilized as an eco-friendly and low-cost statistical approach for the elimination of 2,4-D.