Sustainable Cross-linked Porous Corn Starch Adsorbents with High Methyl Violet Adsorption
Abstract
The present paper reports the preparation of cross-linked porous corn starch (c-PCS) with high methyl violet adsorption capabilities. To obtain c-PCS, the pre-alkalization of porous corn starch (PCS) was first performed using sodium hydroxide/sodium chloride (NaCl/NaOH), followed by the cross-linking of PCS employing epichlorohydrin (ECH) as the cross-linking reagent. The effects of key experimental parameters, i.e. the mass ratio of NaOH to PCS (mNaOH/mpcs), the mass ratio of NaCl to PCS (mNaCl/mpcs), the temperature (Ta) and reaction time (ta) during the alkalization process, the ratio of ECH volume to the mass of PCS (VECH/mpcs), the ratio of solution volume to the mass of PCS (Vs/mpcs), pH value, the temperature (Tc), and the reaction time (tc) in the cross-linking reaction, on the adsorption capability of c-PCS using methyl violet as an adsorbed model were investigated in details. A maximum adsorption capability of 48.3 % was achieved with the following optimum experimental parameters: mNaOH/mpcs= 0.02, mNaCl/mpcs= 0.06, Ta= 40 oC, ta= 1.0 h, VECH/mpcs= 0.003 (mL/g), V/m = 7 (mL/g), pH=10, Tc= 20oC, tc= 3.0 h. The improved adsorption performance was caused by the changed morphology as confirmed by the scanning electron microscope image.