Preparation and characterization of magnetic chitosan-modified diatomite for the removal of gallic acid and caffeic acid from sugar solution

The phenolic substances in sugar cane juice affect the color value of white sugar. A magnetic chitosan-modified-diatomite (MCMD), as a new type of clarifying agent for sugar, prepared via a co-precipitation method combined with cross-linking treatment was firstly used to adsorb two primary phenolic acids of sugarcane juice: gallic acid (GA) and caffeic acid (CA). The maximum adsorption capacities for GA and CA by MCMD were 31.949 mg g-1 and 27.640 mg g-1, respectively. Additionally, our results showed that adsorption of GA and CA on MCMD fitted well with the pseudo-second-order model and Langmuir equation, respectively. The adsorption, a physical spontaneous endothermic process, might have involved electrostatic attraction and micropore filling. Importantly, MCMD has good regenerability and achieves better sulfur-free clarification of sugar cane juice and improves more significantly the food safety of white sugar than the traditional decolorization method.