Column regeneration studies The columns

3.3. Column regeneration studies
The columns used for studying the effect of PD 153035 HCL on continuous flow biosorption were evaluated as to their potential for regeneration and reuse. Successful regeneration is a key process for the determination of the applicability of a sorbent in a water purification application.
The column was regenerated as described previously. During the regeneration almost 96% of the biosorbed Cu2+ was flushed with the first 100 ml batch, while another 3% is contained in the next two batches of the flush solution. The resulting solution was highly acidic as it contained the HNO3 used for the regeneration. Smaller HNO3 exposure times for the regeneration were found to cause small reduction in the subsequent biosorption cycle as 4 h of exposure to acid resulted in a 1% reduction of biosorption (data not presented).
The regeneration data under different pH conditions reveal very good regeneration properties for C. crinitophylla biomass, especially for the higher pH value where it retained almost 100% of the Cu2+ sorption capacity even after 35 consecutive sorption-regeneration cycles ( Fig. 6).