Flocculation properties and adsorption kinetics of cationic starches in kaolin suspensions

Abstract

The flocculation characteristics of cationic starches with degree of substitution (DS 0.32-0.63) have been evaluated in 1.0 wt % kaolin suspension by spectrophotometry and colloid titration. Cationic starch is found to be an effective flocculant for removal of anionic suspension particles. Changes in the electrokinetics of kaolin as a function of pH were investigated in the absence of flocculant. The results show that kaolin in water exhibits a negative surface charge at pH > 2.5. The negative hydrophilic surface sites of kaolin are responsible for the adsorption of cationic starch molecules. The experimental data of the adsorption of cationic starch (DS 0.51) follow a Langmuir isotherm with maximum adsorption capacities of 16.89 mg/g. For the adsorption of cationic starch, chemical reaction seems significant in the rate-controlling step and the pseudosecond-order chemical reaction kinetics provides the best correlation for the experimental data.

Flocculation of kaolin and lignin by bovine blood and hemoglobin

“…Reduced internal repulsive forces allow the structure of HEM to be less rigid and have a more relaxed configuration which enhances bridging flocculation. The effect of NaCl observed in this study is similar to the effect of salt in other flocculation systems: It has been observed that the salts CaCl 2 , KCl and NaCl increase the flocculant effectiveness of cationic chitosan, cationic glucomannan, cationic starch, and cationic synthetic flocculant …”

Synthesis and flocculation behavior of cationic konjac glucomannan containing quaternary ammonium substituents

“…Then, the absorbency of the supernatant liquid was measured at 550 nm25 with a spectrophotometer (Spectrophtotmeter‐722, Xiamen Xingao Instruments Factory, Xiamen, China). Flocculation efficiency (FE) was calculated according to the following formula:2, 25 where A 1 and A 0 are the absorbencies of the clarified layer after and before flocculation, respectively.…”

“…Recently, flocculants based on natural polymers, which are pollution‐free, biodegradable, and low‐cost and have a wide range of applications, have attracted much attention from many researchers. A large amount of work has been carried out to develop flocculants based on starch,1–3 chitosan,4, 5 cellulose,6, 7 guar gum,8 and other natural polymers. Konjac glucomannan (KGM), a neutral polysaccharide, is the main component of the tuber of Amorphophallus konjac C. Koch.…”

Gum ghatti and poly(acrylamide-co-acrylic acid) based biodegradable hydrogel-evaluation of the flocculation and adsorption properties

“…Hydrogel polymers are mostly characterized by their ability to swell in water, therefore, the swelling capacity of the Gg-cl-P(AAMco-AA) hydrogel polymer was examined in double distilled water at different time intervals (4,8,12,16,20 and 24 h), varied temperatures (30, 40, 50, 60 and 70 C) and pH (3.0e13.0). For swelling experiments the same procedure was followed as described under Section 2.2 and the P s was calculated by using Eq.…”