Adsorption of bromophenol blue from aquatic media using polymer-modified silica fume: Factorial design optimization, kinetic evaluation and adsorption mechanism

A novel adsorbent amino-functionalized mesoporous silica composite was synthesized by modification of silica fume (SF) with diethylene triamine (DETA)-trimesoyl chloride (TMC) for sequestration of bromophenol blue (BPB) dye from aquatic media. The synthesized SF/p(DETA-TMC) composite was characterized for surface chemical features, structural characteristics, and morphology by Fourier-transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), and scanning electron microscopy (SEM). Factorials design in central composite design (CCD) using response surface methodology (RSM) was applied to estimate the influence of adsorption and interactions of adsorption parameters such as contact time, pH, adsorbent dose, and initial dye solution. The obtained maximum adsorption uptake capacity from the non-linear Langmuir isotherm model was 255.7 mg/g with optimized 10 ppm concentration within around 30 min contact time and 300 mg adsorbent dose, at pH 5.0. The adsorption kinetic mechanism for BPB dye adsorption by composite adsorbent was recognized well by the pseudo-second-order kinetics. The regeneration performance test resulted in attaining 70/66 % removal of dye after five times-adsorption/desorption cycles. The adsorption mechanism between surface functional groups of the composite adsorbent and BPB dye molecules predominantly occur by π–π stacking, filling of pores, and hydrogen bonding. The SF/p(DETA-TMC) composite polymer had high removal performance and good potential for effective treatment of wastewater.