Determination of surface properties of iron hydroxide-coated alumina adsorbent prepared for removal of arsenic from drinking water.
A novel type adsorbent was prepared by in situ precipitation of Fe(OH)3 on the surface of activated Al2O3 as a support material. The iron content of the adsorbent was 0.31+/-0.003% m/m (56.1 mmol/g); its mechanical and chemical stability proved to be appropriate in solutions. The total capacity of the adsorbent was 0.12 mmol/g, and the pH of zero point of charge, pH(zpc) = 6.9+/-0.3. Depending on the pH of solutions, the adsorbent can be used for binding of both anions and cations, if pH(eq) < pH(zpc) anions are sorbed on the surface of adsorbent (S) through [SOH2+] and [SOH] groups. A graphical method was used for the determination of pH(iep) (isoelectric points) of the adsorbent and values of pH(iep) = 6.1+/-0.3 for As(III) and pH(iep) = 8.0+/-0.3 for As(V) ions were found. The amount of surface charged groups (Q) was about zero within the a pH range of 6.5-8.6, due to the practically neutral surface formed on the adsorption of As(V) ions. At acidic pH (pH 4.7), Q = 0.19 mol/kg was obtained. The adsorption of arsenate and arsenite ions from solutions of 0.1-0.4 mmol/L was represented by Langmuir-type isotherms. A great advantage of the adsorbent is that it can be used in adsorption columns, and low waste technology for removal of arsenic from drinking water can be developed.
Hlavay
József
J
Department of Earth and Environmental Sciences, University of Veszprém, 8201 Veszprém, P.O. Box 158, Hungary. hlavay@almos.vein.hu
Polyák
Klára
K
D000327:Adsorption; D000536:Aluminum Hydroxide / Q000737:chemistry*; D000537:Aluminum Oxide / Q000737:chemistry*; D001149:Arsenates / Q000737:chemistry / Q000302:isolation & purification; D001151:Arsenic / Q000737:chemistry* / Q000302:isolation & purification; D001152:Arsenicals / Q000737:chemistry; D005290:Ferric Compounds / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007526:Isoelectric Point; D055672:Static Electricity; D013499:Surface Properties; D018508:Water Purification / Q000379:methods*
D001149:Arsenates; D001152:Arsenicals; D005290:Ferric Compounds; C021024:ferric hydroxide; D000536:Aluminum Hydroxide; C069471:aluminum oxide hydroxide; D000537:Aluminum Oxide; D001151:Arsenic; C025657:arsenic acid