Synthesis of a Novel Multifunctional Nano Silica-based Polymer Composite for Efficient Removal of Dye From Wastewater

Herein, an in-situ process was successfully adopted for a two-steps reaction in one pot to develop a composite of a novel polymer and silica nanoparticles. The synthesis of this composite was envisaged by using a commercial polymer poly (isobutylene-alt-maleic anhydride) (PIMA) and (3-aminopropyl) triethoxysilane (APTES). The novel composite PIMA-SiO₂ was systematically characterized by various techniques such as FTIR, CP-Mass ¹³CNMR, SEM, EDS, BET, and TGA. The point of zero charge (pHpzc) was determined on the composite and found 8.70. The specific surface area (SSA) of the composite was 68.0 m² g⁻¹ and it classified the composite as mesoporous material. The adsorption results show that the uptake of methylene blue (MB) was highly dependent on contact time and pH of the solution. Adsorption isotherm models (i.e. Langmuir, Freundlich, and Temkin), and kinetic models (i.e. pseudo-first-order (PFO), pseudo-second-order (PSO), Elovich, and Intra-particle diffusion (IPD)), were employed. Temkin isotherm and PSO models were found to be the best fit for adsorption of MB. The maximum MB adsorption capacity was found to be 176.53 mg g⁻¹ at 25 °C. The presence of various salts exhibited an inhibitory effect during MB uptake onto PIMA-SiO₂. Under the experimental conditions, MB uptake was thermodynamically favorable and endothermic. The main contributory mechanisms toward MB uptake onto the composite involved electrostatic interaction, H-bonding, pore-filling, and van der Waals forces. The high uptake capacity and subsequent capability to be recycled in multiple cycles support the PIMA-SiO₂ composite to become an encouraging adsorptive material for the removal of MB from wastewater.