Synthesis of green magnetic biopolymer tannin gel in the simultaneous removal of Malachite green and Sunset Yellow dyes

In the current work, a novel bioadsorbent containing polyhydroxyphenyl groups was created employing the interior layer of oak fruit hull (Oak Gal) extract as a tannin-based magnetic porous organic polymer. Magnetic oak tannin gel (Fe3O4-OT) was created and evaluated for the effective and simultaneous adsorption of cationic (Malachite Green, MG) and anionic (Sunset Yellow, SY) dyes in aqueous solutions. First-order derivative spectrophotometry was used to investigate the simultaneous absorption of the two dyes for MG and SY concentration assessment and the issues produced by the overlap of the dye s spectrum. The response surface methodology (RSM) was then utilized to construct the tests and improve the process utilizing a central composite (CCD) combined design. The effects of critical parameters such as Fe3O4-OT mass, initial pH, initial dye concentrations, and contact duration on dyes removal efficiency were investigated and optimized. The best match to the experimental data of MG and SY adsorption is provided by a pseudo-second-order kinetic model. Also, Langmuir isotherm models better describe adsorption data. All of the experimental results indicated that the Fe3O4-OT bioadsorbent would be an effective green adsorbent with reusability for removing cationic and anionic colors from wastewater.