Adsorption behavior of activated carbon derived from pyrolusite-modified sewage sludge: equilibrium modeling, kinetic and thermodynamic studies

摘要

Activated carbon was developed from sewage sludge using pyrolusite as an additive. It wasndemonstrated that the removal efficiency of two synthetic dyes (Tracid orange GS and Direct fastnturquoise blue GL) by the produced adsorbent was up to 97.6%. The activated carbon with pyrolusitenaddition had 38.2% higher surface area, 43.8% larger micropore and 54.4% larger mesoporenproduction than ordinary sludge-based activated carbons. Equilibrium adsorption isotherms andnkinetics were also investigated based on dyes adsorption tests. The experimental data were analyzednby the Langmuir and Freundlich models of adsorption, and the results fitted well to the Langmuirnisotherm. The kinetic data have been analyzed using pseudo-first-order, pseudo-second-ordernand intraparticle diffusion equation. The experimental data fitted very well with pseudo-secondordernkinetic model. Activation energies for the adsorption processes ranged between 8.7 andn19.1 kJ molu00011. Thermodynamic parameters such as standard free energy (ΔG0), standard enthalpyn(ΔH0) and standard entropy (ΔS0) were evaluated. The adsorption of these two dyes on the activatedncarbon was found to be a spontaneous and endothermic process in nature.