Efficient removal of humic acid from aqueous solutions using threedimensional/magnetic graphene oxide allylamine/allyl glycidyl ether: optimization by Taguchi design method.

We developed a novel three-dimensional graphene oxide/allylamine/allyl glycidyl ether, and evaluated its adsorption performance for humic acid removal in an aqueous solution. The effective parameters were optimized by the Taguchi design method. Effective parameters on the removal of humic acid, including adsorbent dosage, solution pH, contact time, and temperature were evaluated using an L9 orthogonal array. The optimum parameters were adsorbent dosage of 0.02 g, pH of 6, contact time of 120 min, temperature of 25°C, and the removal efficiency of humic acid was 58%. Also, analysis of variance showed the most significant factors were adsorbent dosage and contact time with 33.58% and 51.62% contribution, respectively. The prepared nanoadsorbent was characterized by Fourier-transform infrared spectroscopy, field-emission scanning electron microscopy with energy-dispersive X-ray analysis, and thermogravimetric analysis. The equilibrium data were evaluated by different isotherm models, where the data followed a Langmuir model with a maximum sorption capacity of 25.97 mg/g. Also, the kinetic adsorption data were well evaluated by the pseudo-secondorder model. The thermodynamic data shown that the sorption of humic acid onto the nanoadsorbent was an exothermic, favorable, and spontaneous process. The regeneration test indicated that the nanoadsorbent could be reused in the water treatment application. This study concluded that nanoadsorbent is a very hopeful nanoadsorbent for the remediation of water polluted by humic acid. [ABSTRACT FROM AUTHOR]