Composite Biosorbents of Metal Ions Based on Yeast Cells and Diatomite

Abstract

The possibility of removing Cu 2+ and Pb 2+ ions from solutions by the yeast cells Rhodotorula glutinis and diatomite (natural mineral) was studied. It is shown that at the concentration of CuSO 4 and Pb(NO 3 ) 2 10 -3 mol/l the removal of metal ions by yeast cells was 59.1 and 72.4% for the ions of Cu 2+ and Pb 2+. The yeast cells surface includes amino, hydroxyl, phosphate and carboxyl groups which activates sorption ability, because these groups can bind metal ions by ion exchange, donor acceptor and electrostatic interactions. The removal degree of metal ions by diatomite under the same conditions was for Cu 2+ 91.6% and for Pb 2+ 94.7%. To increase the removal degree of metal ions from solutions, the yeast cells were immobilized on the surface of diatomite. In order to attach the negatively charged cells of microorganisms with negatively charged surface of the mineral, the surface of diatomite was modified by polyethylenimine (PEI). As a result, the immobilization degree of Rhodotorula glutinis to the surface of diatomite at the concentration of PEI 0.02 base-mol/l increased from 62 to 88%, which is explained by the existence of electrostatic contacts between the negatively charged functional groups of the cell surface and amino groups of PEI, that has covered the surface of diatomite by PEI. It is shown that the obtained composite biosorbent removes 97.8% of Cu 2+ ions and 99.4% of Pb 2+ ions.

Obtaining sorbents based on natural diatomite

“…Өнеркәсіптік ағынды суларды тазартудың әртүрлі жолдары бар, солардың ішінде ең келешегі зор болып табылатыны табиғи минералдарды адсорбенттер ретінде пайдалану. Ағынды суларды тазарту үшін табиғи минералдарды қолдану экологиялық жағынан да, экономикалық жағынан да қолайлы, бірақ көбінесе мұндай материалдардың қажетті сорбциялық қасиеттері жоқ, сондықтан оларды модифицирлеу қажеттігі туындайды [7].…”

“…Табиғи диатомиттің меншікті беті, әдетте, 39 м 2 /г жоғары емес, бұл оған тиімді сорбент болуға мүмкіндік бермейді. Сондықтан, меншікті бетті ұлғайту және беттік сипаттамаларды жақсарту үшін оны модифицирлеу қажет [7].…”

Acid Modification of Diatomite-Based Sorbents

“…The study [15] reports about yeast cells immobilization onto diatomite surface, pre-treated with polyethylenimine with the aim to increase the degree of Pb 2+ removal from solutions. The diatomite/ yeast composite biomaterial was shown to adsorb 97.8% of Cu 2+ ions and 99.4% of Pb 2+ ions [15].…”

In honor of the 75th birthday of Kuanyshbek Bituovich Musabekov

“…He performed complex studies devoted to the surface properties of microorganism cells and the stability of biological dispersions with respect to high-and lowmolecular-mass electrolytes and substantiated the mechanisms of the bactericidal, coagulating and flocculating action of electrolytes, polymers, and polymer-surfactant complexes on suspensions of microorganism cells. The conditions were optimized for the production of immobilized biocatalysts, representing a new generation of catalysts based on yeast cells, as well as efficient biosorbents which at an optimal ratio of metal/biosorbent provide a high degree of purification of waste water [12,13]. The data given in Table 1 give an example of such an application.…”