Optimization of parameters for doping of metals on activated carbon for respirator applications

Abstract

To remove different contaminants from an effluent waste stream, it is imperative that a suitable material having considerable adsorption tendency must be selected. Activated carbon (AC) is considered as the best candidate to accomplish this goal. Core objective of this work is to enhance capability of activated carbon to adsorb gases of low molecular weight and high volatility by impregnating specific metals on the surface of activated carbon using various salts in different medium i.e. basic and neutral. Imbibing limit is used as the method of impregnation and shaking time is nearly one minute after introducing few drops of impregnating solution. Final form of impregnant is either oxide or sulphate while oxide is the desirable form because in this form of impregnant, the sample needs not to be heated at elevated temperatures to remove volatiles or calciners. Mass variations of samples with rise in temperature give clue that at 160 °C calciners are removed from the surface of activated carbon. BET surface area analysis gives information that after impregnation there is no considerable change in the value of available pores of activated carbon, which is contrary to previous research. AAS results confirm that metal doping in alkaline medium has imparted a comparatively higher concentration of zinc metal to the AC surface as compared to impregnation in neutral medium. In addition, optimized concentration of zinc oxide in alkaline (ammonia solution) medium was 1.17 M of zinc oxide and in neutral medium it is 0.4 M. Optimized temperature to heat the sample to remove volatiles is 160 °C. Peaks of zinc oxide are not prominent at low temperature, nevertheless when temperature of sample is raised up to 450 °C, the peaks become prominent and the results match well with available literature.