Adsorption of Cationic Methylene Blue and Anionic Methyl Orange by Crude Drug Starches

摘要

In order to use effectively the starch from the extracted residue of crude drugs,adsorption characteristics of cationic methylene blue(MB)and anionic methyl orange(MO)were investigated.Starches(S)were prepared from the roots of Panax ginseng C.A.Meyer(PG)and Panax notoginseng(Burk.)F.H.Chen(PN),the rhizomes of Pinellia ternate(Thunb.)Breitenbach(PT)and Alisma orientate Juzepczuk(AO),and the seeds of Coix lacrymajobi Linne var.ma-yuen Stapf(CL).The adsorption isotherm was evaluated using Akaike's information criterion(AIC)value,and the adsorption of cationic MB and anionic MO by the starches was classified into the Langmuir type and Freundlich type,respectively.The starches adsorbed more MB than MO.The amounts adsorbed were affected not by the particle size or the content of cationic minerals,but by the phosphorus content.Cationic MB was adsorbed more strongly than anionic MO on the negatively charged surface of the starches because of the presence of phosphorus.S-CL was superior in adsorption capacity for both cationic MB and anionic MO to S-PG,S-PN,S-PT,S-AO,and S-ST(potato starch)at 5 and 25deg C.S-CL had a porous and stripe structure on the granular surface,and contained a small amount of phosphorus.