title: Removal of metal ions by modified Pinus radiata bark and tannins from water solutions.
abstract: Pinus radiata bark and tannins, chemically modified with an acidified formaldehyde solution were used for removing metal ions from aqueous solutions and copper mine acidic residual waters. The adsorption ability to different metal ions [V(V), Re(VII), Mo(VI), Ge(IV), As(V), Cd(II), Hg(II), Al(III), Pb(II), Fe(II), Fe(III), Cu(II)] and the factors affecting their removal from solutions were investigated. Effect of pH on the adsorption, desorption, maximum adsorption capacity of the adsorbents, and selectivity experiments with metal ion solutions and waste waters from copper mine were carried out. The adsorbents considerably varied in the adsorption ability to each metal ion. The adsorption depends largely upon the pH of the solution. Modified tannins showed lower adsorption values than the modified bark. For the same adsorbent, the maximum capacity at pH 3 for the different ions were very different, ranging for modified bark from 6.8 meqg(-1) for V to 0.93 meqg(-1) for Hg. Waste waters were extracted with modified bark as adsorbent and at pH 2. The ions Cu(II) (35.2 mgL(-1)), Fe(III) (198 mgL(-1)), Al(III) (83.5 mgL(-1)) and Cd(II) (0.15 mgL(-1)) were removed in 15.6%, 46.9%, 83.7% and 3.3%, respectively, by using 1g of adsorbent/10 mL of waste water. In general, a continuous adsorption on a packed column gave higher adsorbed values than those observed in the batchwise experiment.
authors: Departamento de Ciencias Químicas, Universidad de La Frontera, Casilla 54-D, Av. Francisco Salazar, 01145 Temuco, Chile. gpalma@ufro.cl
authors: Graciela
authors: G
authors: Palma
authors: Juanita
authors: J
authors: Freer
authors: Jaime
authors: J
authors: Baeza
mesh_terms: D000327:Adsorption; D001673:Biodegradation, Environmental; D003247:Conservation of Natural Resources; D019216:Metals, Heavy / Q000302:isolation & purification*; D008906:Mining; D028223:Pinus; D024301:Plant Bark / Q000737:chemistry; D013634:Tannins / Q000737:chemistry*; D014873:Water Pollutants / Q000302:isolation & purification*; D018508:Water Purification / Q000379:methods*
chemical_list: D019216:Metals, Heavy; D013634:Tannins; D014873:Water Pollutants