Recycling of industrial solid waste for the removal of mercury (II) by adsorption process

Fe(III)/Cr(III) hydroxide, a waste byproduct obtained from the treatment of Cr(VI) containing wastewaters in a fertilizer industry, has been used for the adsorption of Hg(II) from aqueous solution. The influence of various parameters such as metal ion concentration ( 10–40 mg/L), agitation time (1–160 min), adsorbent dosage (5–250 mg per 50 ml), temperature (24 – 44°C) and pH value (4 – 10) on the removal of Hg(II) has been studied. The adsorption follows both Langmuir and Freundlich isotherm models. The applicability of the Lagergren kinetic model has been investigated. Almost quantitative removal of Hg(II) from a solution containing 40 mg/L in a 50 al solution by 175 mg of adsorbent occurred at an initial pH of 5.6. Adsorption was uniformaly high (91 X) in the initial pH range 4.0 to 10.0. Temperature studies showed that the adsorption process was endotheraic in nature. Desorption of Hg(II) showed that it is solubilised in 2 % KI to the extent of 65 %.