Adsorption characteristics of Orange II and Chrysophenine on sludge adsorbent and activated carbon fibers.

Sludge adsorbent (SA) and commercial activated carbon fibers (ACFC and ACFT) were applied to Orange II and Chrysophenine (CH) adsorption (BET surface area: ACFC>ACFT>SA). ACFT was primarily in the micropore range, while SA was approximately 500 A (macropore) and 80 A (mesopore). The ACFC pore volume was high in both the mesopore and micropore regions. Measurement of the oxygen surface functional groups of the adsorbents using Boehm's titration method showed a similar distribution on the carbon fibers (mainly in the carbonyl group), while SA was mainly in the carboxyl, lactone and phenolic groups. The SA, ACFC and ACFT adsorption capacities of Orange II (30-80 mg/l) ranged from 83 to 270, 209-438, and 25-185 mg/g at temperatures ranging from 10 to 60 degrees C, respectively. CH concentration ranged from 30 to 80 mg/l, corresponding to SA and ACFC adsorption capacities of 39-191 and 48-374 mg/g over the defined temperature range, from 10 to 60 degrees C. CH adsorption on ACFT was low. The adsorption capacity of Orange II on ACFT was lower than on SA at 10 degrees C, but at higher temperatures the Orange II molecules were transported into the ACFT, producing an adsorption capacity similar to that of SA. Mass transfer increased with temperature, overcoming the adsorption energy barrier. Overall, SA and ACFC were more effective than ACFT.