ADSORPTION OF P-NITROPHENOL ON CARBON-BLACK - TEMPERATURE EFFECT

Using a number of carbon black samples, which in some instances showed very different textural properties and adsorption capacity, the effect of temperature on the adsorption of p-nitrophenol (PNP) from aqueous solution was investigated. From the adsorption isotherms determined at 20, 30 and 40-degrees-C, the plot of b (the slope of ln X = a + bT, where X was the amount of PNP adsorbed) against the relative concentration (C/C0) enabled us to compare the thermal stability of the adsorbed state for all adsorbents and to follow its variation with C/C0. The stability was strongly dependent on textural properties of the adsorbents. It was lower when the adsorption occurred on the external surface or in large pores than when the process took place in micropores. The influence of the lateral interactions on the stability appeared to be marked. The stability of the adsorbed state at high surface coverages and above the first adsorption layer as well as the activated diffusion process could also be studied.