Sorption profile of mercury (II) from aqueous solution onto low-rank Pakistani coal

Abstract

The adsorption of mercury ions on low-rank Pakistani coal (LPC) has been studied as a function of shaking time, nature of electrolytes (HClO 4 , H 2 SO 4 and HNO 3), dose of adsorbent, metal ion concentration and temperature. The radio tracer technique was applied to examine the distribution of mercury (Hg 2+) using a batch method. Maximum adsorption was found to be at 0.0001 mol L −1 of HNO 3 solution, using 0.15 g of adsorbent for 4 mL of 4.985 × 10 −4 mol L −1 mercury concentration with equilibration time of 10 min. The adsorption of mercury was decreased with the increase in the concentrations of all the mineral acids used. The kinetic data indicated an intra particle diffusion process with sorption being pseudo-second order. The determined rate constant k 2 was 0.449 g mg −1 min −1. The adsorption data obeyed the Langmuir, Freundlich and Dubinin-Radushkevich isotherm plots over the mercury concentration range of 4.985 × 10 −4 to 2.991 × 10 −3 mol L −1. The characteristic Freundlich constants i.e. 1/n = 0.160 and K = 1.052 × 10 −1 m mol g −1 whereas the Langmuir constants Q = 3.531 × 10 −2 m mol g −1 and b = 28.522 × 10 3 dm 3 mol −1 have been calculated for the adsorption system. The uptake of mercury was increased with the rise in temperature (283−333 K). Thermodynamic quantities i.e. ∆H, ∆G and ∆S have been computed and discussed for the system. Sorbent was characterized by using SEM and FT-IR before and after the adsorption of mercury. Effect of diverse ions on the adsorption of mercury has also been investigated. Removal of mercury from tap water sample shows the applicability of the proposed method.

Adsorption Processing for the Removal of Toxic Hg(II) from Liquid Effluents: Advances in the 2019 Year

“…Several variables were investigated in the adsorption of Hg(II) by low-rank Pakistani coal (LPC) [39]. Maximum Hg(II) adsorption was found to be 1 × 10− 4 M nitric acid solutions, using a 38 g/L adsorbent dosage and 10 min of reaction time.…”