Equilibrium, kinetic and thermodynamic studies of mercury adsorption on almond shell

Abstract

The application of almond shell as a low cost natural adsorbent to remove Hg(2+) from aqueous solution was investigated. Batch experiments were carried out to evaluate the adsorption capacity of the material. The chemical and physical parameters such as pH, sorbent amount, initial ion concentration, and contact time were optimized for the maximum uptake of mercury onto the solid surface. Adsorption isotherms were expressed by Langmuir and Freundlich adsorption models, and the experimental data were found to fit the Langmuir model rather than the Freundlich. The maximum adsorption capacity obtained from the Langmuir isotherm was 135.13 mg/g. A kinetic study was carried out with pseudo-first-order and pseudo-second-order reaction equations and it was found that the Hg(2+) uptake process followed the pseudo-second-order rate expression. The thermodynamic values, ΔG(0), ΔH(0) and ΔS(0), indicated that adsorption was an endothermic and spontaneous process. The potential of this material for mercury elimination was demonstrated by efficient Hg(2+) removal from a synthetic effluent.

Zero valent cobalt impregnated silica nanoparticles for the sanitation of contaminated water

“…The positive value of Δ S ° reflected an increased degree of randomness at the solid/liquid interface during adsorption of all the three contaminants. Similar type of observations have been made during adsorption studies of MB , TNT , and Hg (II) by different researchers.…”

“…However, the linear plot of t / q t versus t evidently showed that the experimental results and the calculated values of q e (Table ) obtained by the pseudo‐second‐order kinetic model were comparable [Supporting Information, Figure S8(b)]. The values of R 2 (0.998–0.999) calculated from the pseudo‐second‐order‐kinetic model were relatively higher than those for the pseudo‐first‐order model (0.828–0.994), indicating that the pseudo‐second‐order adsorption mechanism was dominant in the adsorption process of Hg (II) on Co/SiO 2 .…”

“…The R 2 values (Table ) of Langmuir isotherm (0.998) was found relatively higher than that of Freundlich (0.984). It indicated that the adsorption behavior may be well fitted to the Langmuir isotherm model involving homogeneous monolayer adsorption process . Based on the experimental results, the maximum adsorption capacity ( q m ) of Hg (II) on Co/SiO 2 was calculated to be 40.24 mg/g (Table ).…”

Selective and sensitive determination of Cd(II) ions in various samples using a novel modified carbon paste electrode

“…The obtained residues were dissolved in 20 mL of bi-distilled water and filtrated by filter paper. The filtrate was diluted by 50 mL of bi-distilled water (Khaloo et al 2012). Aliquots of the solution were introduced to the proposed methodology for Cd(II) investigation.…”

Control of mercury emissions: policies, technologies, and future trends

“…107,108 Moreover, the use of agricultural products and by-products has been widely investigated as a replacement for current adsorbents for removing mercury and mercury compounds from gas, water, and wastewater. 109 Also, the best available adsorption technologies to control mercury emission will be considered by the performance and cost. Therefore, advanced adsorption technology and adsorption behavior on mercury will be developed by economic and environmental evaluations for the adsorbents with additives to prevent mercury release into the atmosphere.…”