adsorption of the reactive azo dyes onto nh4cl-induced activated carbon

background: the efficacy of nh4cl-induced activated carbon (nac) was examined in order to adsorb rr198, an azo reactive model dye, from an aqueous solution. methods: the effects of ph (3 to 10), adsorbent dose (0.1 to 1.2 g/l), dye concentration and contact time on the adsorption efficiency were investigated. results: the results showed that the removal of dye was highest at a solution ph of 7 and a powder dose of 1.1 g/l. the 85.9%, 72.6% and 65.4% removal of rr198 was obtained for a concentration of 25, 50 and 100 mg/l, respectively, at a relatively short contact time of 30 minutes, and at optimum ph and nac concentrations of 1 g/l. the experimental data for kinetic analysis illustrated a best fit to the pseudo-second-order model. the study data on equilibrium were modeled using langmuir, freundlich and dubinin–radushkevich models; the langmuir equation provided the best fit for the data. conclusion: therefore, the nac appears to be an efficient and appropriate adsorbent for the removal of reactive azo dyes from waste streams.