Adsorption of liquid fuel dimethyl amino ethyl azide from dilute aqueous solution on activated carbon prepared from walnut shell

Dimethyl amino ethyl azide (DMAZ) is a non-carcinogenic liquid fuel in space programs. Low concentrations of DMAZ should be separated from dilute aqueous solution to prevent the environmental pollution. Activated carbon, prepared from walnut shell through zinc chloride activation, was characterized and assessed to remove DMAZ from dilute aqueous solutions. At initial concentration of 500 ppm of DMAZ, the optimum conditions were obtained as pH 10, agitation speed of 100 rpm, and adsorbent dosage of 0.29 g. Under the optimized conditions, the removal percentage was obtained as 85.95%. Adsorption data for DMAZ uptake by the activated carbon was analyzed according to Langmuir, Freundlich, Tempkin, and Dubinin–Radushkevich (D–R) adsorption models. The results indicated that the Freundlich model agreed well with the isotherm data. Among the pseudo-first-order, pseudo-second-order, Elovich, and intraparticle diffusion kinetic models, the kinetic process can be described by a pseudo-second-order rate equation very well. It was found that the activated carbon prepared from walnut shell could be considered as an appropriate adsorbent for DMAZ in dilute aqueous solution.