Removal of Pb(II) from aqueous solution by natural and synthetic calcites

Abstract

ABSTRACT. A comparative evaluation of the adsorption capacity and kinetics of Pb(II) uptake by both synthetic and natural calcites has been undertaken using batch equilibration technique. The originality of the calcite materials was confirmed by XRD and elemental composition by XRF. The point of zero charge values of 9.57 and 8.20 were obtained by mass titration method for synthetic and natural calcite, respectively. The maximum adsorption capacities of 200 mg/g and 150 mg/g Pb(II) of synthetic calcite and natural calcite were obtained at initial lead loading of 1200 mg/L at 25±2 °C, respectively. The study showed a very slight dependence of sorption capacity on the ionic strength and pH, but a strong dependence on the particle size and contact time. The sorption data results fitted better the Langmuir than the Freundlich isotherms. The kinetic data fitted well to pseudo-first order sorption kinetic model with a regression coefficient value of 0.96 and 0.94 for synthetic and natural calcites, respectively. Desorption of Pb(II) from calcite surface was achieved with efficiency of 95% using 4 M HNO3. The extent of reversibility of sorption reaction was a function of the equilibrium pH of calcite-Pb(II) solution suspension.

Adsorption studies of zinc(II) on magnetite, baobab (Adansonia digitata) and magnetite–baobab composite

“…The isotherm yielded a good linear plots having Freundlich adsorption intensity, n, constant for Zn(II) on MG, (4) The n values predict whether the adsorption of a given ion is favourable or not. Since n > 1 for adsorption of Pb(II) and Zn(II), the adsorption intensity is favourable at higher concentration (Adekola et al 2011)]. Figure 8 represents the Temkin isotherm behaviour for the adsorption of Zn(II) on magnetite, baobab and magnetite-baobab composite.…”

A novel zerovalent manganese for removal of copper ions: synthesis, characterization and adsorption studies

“…ions concentrations using atomic adsorption spectrophotometer (AAS) model AA320 N. The determination of the residual concentration using AAS was done in triplicate and the mean value for each set of the experiments was calculated. Investigation of other operational parameters such as effects of pH, contact time, adsorbent dose, temperature and ionic strength was carried out following a similar procedure (Adekola et al 2012;Hao et al 2010). Adsorption capacity and the removal efficiency were obtained using Eqs.…”

Kinetics, thermodynamics and competitive adsorption of lead and zinc ions onto termite mound

“…The n value indicates whether the nature of adsorption is favourable or otherwise. A value less than 1 indicates that sorption intensity is favourable over the entire range of concentration, while a value greater than 1 favours sorption at higher concentration (Adekola et al 2011). It could be concluded from the value obtained that the adsorption is favourable at higher concentrations for both Pb(II) and Zn(II).…”