THE USE OF LOW-RANK COAL-BASED ADSORBENTS FOR THE REMOVAL OF NITROPHENOL FROM AQUEOUS-SOLUTION

A range of Victorian brown coal based materials (Yallourn brown coal, grus, briquette char, power station char and an activated carbon) have been assessed as potential adsorbents for the removal of organics from aqueous wastes. The compound il-nitrophenol has been used as the adsorbate. The influence of adsorbent dosage levels, particle size, and the presence of buffer solution components, other electrolytes, and pH on the kinetics of adsorption of nitrophenol have been investigated. For some adsorbents, pH changes in the acidic region appear to have little influence on adsorption rates of nitrophenol, but for chars, reduced pH conditions appear to reduce adsorption rates. In the alkaline pH range, leaching from some of the adsorbents occurs, with the extent of leaching reducing as the carbon content of the adsorbent increases. Adsorption capacities for Yallourn coal, grus, briquette char and power station char using nitrophenol in phosphate buffer have been measured. The technique of differential pulse polarography has been shown to be useful as a means of measuring nitrophenol adsorption in situ for concentrations up to 30 mg l(-1).