Adsorption Characteristics of Starch Digested with Alkali on Fine Hematite Particles

Abstract

In this paper, the influence of alkali on the flocculation of starch on fine hematite was investigated through a series of tests, like turbidities, paste titration, adsorption, conductance, scanning electron microscope (SEM) measurement, and Fourier transforms infrared spectroscopic analysis (FTIR) as well. The results pointed out that alkali concentration has a strong influence on physicochemical changes of starch granules, inducing different adsorption densities on mineral surfaces. A maximum amount of adsorption density on mineral particles was harvested for the starch digested with sodium hydroxide at a concentration of 0.4 N/g starch. It is worthy to note that starch is not fully digested in the presence of alkali at a concentration of less than 0.4 N/g starch. Higher concentration of hydroxide ions, however, tends to obtain less adsorption density of starch on hematite because too small remnants in the starch gel have inverse effects on adsorption capacity.