Adsorption of Divalent Copper, Zinc, Cadmium and Lead Ions from Aqueous Solution by Waste Tea and Coffee Adsorbents

Abstract

The adsorption of the divalent cations of Cu, Zn, Cd and Pb by tea leaves and coffee grounds from aqueous solutions is described. Both adsorbents exhibited strong affinity for these ions which could be described by a simple single-site equilibrium model. For coffee, the order of increasing adsorption equilibrium constant K was Cu < Pb < Zn < Cd, while for tea the opposite order was observed indicating that the adsorption sites on each adsorbent have a different chemical nature. Adsorption decreased at low pH < 4 through competition with H+ for adsorption sites, and for all metals except Cu, at high pH > 10, probably because of anion formation in the case of Zn2+ and also increased leaching of metal-binding soluble materials. The effect of metal ion concentration on the adsorptive equilibria indicated a threshold concentration above which overall adsorption became limited by saturation of the adsorption sites. Competition between two metal ions for the same sites was not observed with Cu(II) and Pb(II), however Zn(II) reacted competitively with Cd(II) binding sites on both tea and coffee. If fresh coffee or tea adsorbents were used, the fraction of metal ion taken up by the adsorbent was diminished by the competitive effects of soluble metal-binding ligands released by the tea or coffee. Experiments with coffee showed that roasting temperature controls the formation of metal ion adsorption sites for this adsorbent.

Recycling coffee and tea wastes to increase plant available Fe in alkaline soils

“…Results showed that protocatechuic acid was the weakest chelator (1.43 M −1 ), followed by hydroxytyrosol (2.66 M −1 ), gallic acid (4.78 M −1 ), caffeic acid (8.12 M −1 ) and chlorogenic acid (20.13 M −1 ). The adsorption of divalent cations of Cu, Zn, Cd and Pb by coffee grounds and tea leaves from aqueous solutions was described by Utomo and Hunter (2006). Both materials exhibited strong affinity for these ions, which could be described by a simple single-site equilibrium model.…”

Spent coffee grounds as a valuable source of phenolic compounds and bioenergy

“…In particular, some studies have highlighted the possibility of using SCG to remove basic dyes (Franca et al, 2009) or heavy metal ions (Tokimoto et al, 2005;Utomo and Hunter, 2006;Zuorro and Lavecchia, 2010) from contaminated waters. For metal ions, the order of adsorption capacity was Cd 2þ gt; Zn 2þ gt; Pb 2þ gt; Cu 2 and the effectiveness of metal removal was higher between pH values of 4 and 10 (Utomo and Hunter, 2006). These properties seem to be closely related to the presence of phenolic compounds with metalchelating properties and to the protein content.…”

Biosorption of Cu(II) and Pb(II) from aqueous solutions by chemically modified spent coffee grains

“…A number of authors have reported the use of coffee by-products to remove either organic (Boonamnuayvitaya et al 2004;Oliveira et al 2008) or inorganic (Utomo and Hunter 2006) pollutants from water.…”