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The phosphoric acid activated carbon (PAC) was derived from waste wooden pallets by a two-step chemical activation technique, carbonization and phosphoric acid activation in sequence. A widely used commercial activated carbon, Calgon Filtrasorb 400 (F400), was studied in parallel for comparison. The physical properties and surface chemistry of the activated carbons were characterized using BET-[N.sub.2] adsorption, elemental analysis, Boehm's titration, Fourier transform infrared spectroscopy, and x-ray photoelectron spectroscopy. PAC possessed physical properties (surface area and pore volume) that were comparable to those of F400, but displayed distinct surface chemistry in terms of [pH.sub.PZC] surface acidity and basicity, and surface functional groups. Batch studies were conducted to evaluate the methylene blue (MB) and phenol adsorption capacity of PAC and F400 and their dependence on pH, contact time, and initial adsorbate concentration. Experimental results showed that the solution pH slightly influenced the adsorption of MB and phenol on F400, whereas it had no effect on their adsorption on PAC. Equilibrium adsorption data were fitted with an Langmuir isotherm equation. In comparison with F400, PAC showed a higher adsorption capacity for MB but lower for phenol. Given the comparable physical properties of PAC and F400 and the polar nature of MB and phenol, surface chemistry of the two carbons appeared to determine the adsorption mechanism and capacity. The strongly negative surface of PAC, due to phosphoric acid activation, facilitated the adsorption of positively charged MB, whereas the presence of oxygen-containing functional groups on PAC inhibited phenol adsorption. DOI: 10.106l/(ASCE)0733-9372(2008)134:5(338) CE Database subject headings: Adsorption; Wood; Activated carbon; Phenol.

The rapid small-scale column test (RSSCT) has become a popular method for sizing granulated activated carbon (GAC) systems and columns for water treatment facilities. In this procedure, the GAC is ground and a specific size fraction is used for the RSSCT. Since GAC is produced and activated using different processes from different starting materials (e.g., bituminous, lignite, wood, etc.), the possibility exists that the extent of activation and, hence, the adsorptive capacity and surface reactivity may vary throughout the GAC particles. This would be the case if there were less activated inner cores in the GAC particles. If there is a variation in the sorption properties throughout the GAC particles, then grinding the GAC may result in smaller particles that have different properties than the bulk GAC. This study was carried out to test this commonly assumed hypothesis that the limited-sized ground particles represent the same adsorptive properties as the bulk GAC. Four activated carbons (manufactured from different source carbons) were studied. Gas adsorption tests determined the physical morphology, Boehm's titrations checked the chemical nature of the surface oxides, and the Mohs hardness test was performed on all bulk GACs and ground fractions. No apparent differences were found in the total surface area, cumulative pore volume, or pore size volume of fractions generated by grinding activated carbons. In addition, the Boehm technique did not identify any significant differences in the chemical nature of the surfaces of the various size fractions of GAC. The Mohs hardness test did not indicate any variations in the hardness of the bulk GAC, the ground fractions, and the unground core. Based on the methods and materials used, the underlying assumption in the RSSCT analysis--that there are no variations in the different size fractions of the ground GAC--appears to be correct. DOI: 10.1061/(ASCE)0733-9372(2008)134:3(216) CE Database subject headings: Activated carbon; Columns; Water treatment plants; Adsorption.

Biodegradability of chlorinated aliphatic (carbon tetrachloride) and aromatic (chlorophenol) compounds under acidogenic condition was investigated at pH of 5.0 to 5.5. Batch tests were used to evaluate biodegradability, adsorption capacity, and inhibitory effects of the chlorinated compounds on the fermentative microbial consortium. The biodegradability of carbon tetrachloride differed from that of the chlorophenols tested. Carbon tetrachloride was degraded to dichloromethane, and its adsorption onto the biomass was minimal. Inhibition of the acidogenic process was not observed for carbon tetrachloride at 10 mg/L. Chlorophenols (penta, tri, di, and mono) were not degraded at all, even after addition of vitamin supplements, increased incubation time, and increased primary to secondary substrate ratio. Chlorophenol removed from the aqueous phase by adsorption can be recovered from the acidogenic sludge. Pentachlorophenol was inhibitory to the acidogenic culture, whereas 2-chlorophenol was not. Microbial community analysis revealed the bacteria therein were primarily rumen and enteric bacteria. The results showed that it is possible to dechlorinate at least an aliphatic chlorinated compound under acidogenic conditions. DOI: 10.1061/(ASCE)0733-9372(2008)134:3(177) CE Database subject headings: Adsorption; Degradation; Chlorination.

Endosulfan, one of the most widely used pesticides in various sectors including agriculture, has been reported posing a threat to the ecology as well as to the environment. Contamination of groundwater and surface water sources with various pesticides is well documented, and this problem is prominent, particularly in rural areas. In the present study, efforts are made to remove endosulfan from water using wood charcoal, a local and low cost adsorbent. It gave removal efficiency of more than 90%. Equilibrium time was found to be around 5 h. Wood charcoal showed an uptake capacity of 0.53 mg/g with initial endosulfan concentration in the range of 0.25-5 mg/L and 1.77 mg/g for the range of 2-50 mg/L. Langmuir isotherm gave a better prediction of adsorption capacity than the Freundlich. The Langmuir isotherm fit also gave a better correlation with the experimental data. In the desorption study carried out, 10% solutions of acetone, methanol, acetic acid, saturated EDTA solution, and distilled water were used as eluents. Ten percent methanol solution was found performing well with an adsorbent regeneration of more than 80% after four cycles of adsorption desorption. Desorption was found to follow a zero order equation in the case of 10% solutions of both acetone and methanol. DOI: 10.1061/(ASCE)0733-9372(2008)134:2(102) CE Database subject headings: Adsorption; Desorption; Equilibrium; Abatement and removal; Ecology; Pesticides; Water pollution.