Adsorption process of heavy metals by low-cost adsorbent: a review

In this article, the potential of various low-cost adsorbents for the removal of heavy metals from contaminated water has been reviewed. Various conventional methods for heavy metal removal such as precipitation, evaporation, electroplating and also ion exchange have been applied since previous years. However, these methods have several disadvantages such as only limited to certain concentrations of metals ions, generation large amount of toxic sludge and the capital costs are much too high to be economical. Hence, adsorption using low-cost adsorbents is found to be more environmentally friendly. Adsorption is the alternative process, for heavy metal removal due to the wide number of natural materials or agricultural wastes gathering in abundance from our environment. High adsorption capacities, cost effectiveness and their abundance in nature are the important parameters which explain why the adsorbent is economical for heavy metal removal. In this review, a list of adsorbent literature has been compiled to provide a summary of available information on a wide range of low cost adsorbents for removing heavy metals from contaminated water. The application of available adsorption models such as the isotherm, kinetics and thermodynamics as well as the influence of parameters on metal adsorption by low cost adsorbent shall be reviewed to understand the adsorption mechanism of low-cost adsorbents

Adsorption of Pb(II) ions by using Mangrove-Alginate Composite Beads (MACB): isotherm, kinetics & thermodynamics studies

Present study explored the potential of using mangrove-alginate composite bead (MACB) as adsorbent for the removal of Pb(II) ions from aqueous solution. The batch sorption was studied under different initial concentration (20 to 100 mg/L), contact time (5 to 210 min) and solution temperature (35 to 650C). The Langmuir, Freundlich, and Temkin isotherm models were used to analyze the experimental equilibrium data and isotherm constants. A comparison of kinetic models applied to the adsorption of Pb(II) ions on MACB beads was evaluated using pseudo-first order and pseudo-second order kinetics models. The experimental data were fitted well with the pseudo-second order kinetic model, means the mechanism of diffusion process is controlled by the adsorption reactions and not depend by the mass transfer during adsorption. Based on thermodynamics parameters, the results show that the adsorption capacity increases with an increase in temperature. The negative value of ΔHo (-1.402 kJ mol-1) and the decreasing kd value with increasing temperature, which indicate the sorption of Pb(II) onto MACB beads was feasible and an exothermic reaction. The positive value ΔSo(8.256 Jmol-1K-1) reflects good affinity of Pb(II) ions towards the MACB beads. The results described the potential for the MACB beads to be used as adsorbent for the removal of Pb(II) ions from wastewater

Comparative study on adsorption of PB(II) ions by alginate beads & mangrove-alginate composite beads

The aim of the present study report on the adsorption performance of alginate bead (AB) and mangrove-alginate composite bead (MACB) bead adsorbents for the removal of Pb(II) ions from aqueous solution. The effects of pH and initial concentration with contact time on the adsorption properties of Pb(II) onto both adsorbent were investigated and were described by isotherm and kinetic studies. The isotherm adsorption data were fitted well to Freundlich isotherms for both beads and the maximum adsorption capacities of the AB and MACB beads were 29.02 mg g-1 and 10.84 mg g-1, respectively. The kinetics adsorption data were best described to a pseudo-second-order kinetic models showing that the MACB beads had a higher kinetic adsorption rate at 2.6084 g mg-1 min-1 compared to AB at 0.7043 g mg-1 min-1

Development of novel adsorbent-mangrove-alginate composite bead (MACB) for removal of Pb(II) from aqueous solution

This study described a preparation of novel composite adsorbent for heavy metal removal by immobilized mangrove bark into alginate as supporting matrix. The removal of Pb(II) ions from aqueous solution by mangrove-alginate composite bead (MACB) was investigated by performing batch adsorption studies to evaluate the performances of the bead. It was found that the adsorption of Pb(II) ions by MACB beads was pH dependent, as the maximum percentage removal was obtained at pH 5.0. The results revealed the superior parameters of MACB beads had attained about 99.15% efficiency in conditions of 7 g L−1 MACB concentration, 150 min contact time, 5.0 as the initial pH, and 250 rpm agitation speed. The adsorption kinetic data can be well described using pseudo-second-order model and the equilibrium data were fitted well by Freundlich isothermal model, respectively. Thermodynamic parameters were calculated and revealed that the adsorption process is an exothermic and spontaneous reaction within range of temperature of 35–65 °C. This indicates that the MACB beads can be used as a promising adsorbent for removal of heavy metals from aqueous solutions