Synthesis of porous carbon derived from coal tar residue via bimetallic salt activation for effective and selective adsorption of thallium(I)

As a highly toxic rare metal, the removal of thallium (Tl) from wastewater has been widely investigated, and adsorption is considered one of the most promising treatment technologies for Tl-containing contaminated water because of its cost-effectiveness, convenience, and high efficacy. In this work, coal tar residue (CTR)-based porous carbon was synthesized through K 2 FeO 4 activation, and applied in adsorbing Tl(I). K 2 FeO 4 could synergistically produce porosity and load iron oxide on the produced porous carbon surface because of the catalytic cracking and oxidative etching during the activation of CTR. The adsorbent was synthesized at 800 ℃ with a mass ratio of K 2 FeO 4 /CTR being 3 (PC 3–800 ) showed optimal Tl(I) adsorption performance. The removal efficiency and distribution coefficient of PC 3–800 were above 95 % and 10 4 mL/g, respectively, in a wide pH range (4−10). Furthermore, the selection and reusability of PC 3–800 were favorable. The adsorption was a spontaneous, exothermic, and entropy increase process. The adsorption process was dominated by electrostatic attraction, surface complexation, and surface oxidation . The results suggested that removing Tl(I) from contaminated water via CTR-based porous carbon was feasible.