Evaluation of Activated Carbon from Fluted Pumpkin Stem Waste for Phenol and Chlorophenol Adsorption in a Fixed –Bed Micro-Column

Fluted pumpkin stem waste, which is both a waste and pollutant, was chemically modified with ortho-phosphoric acid and used to adsorb phenol and chlorophenol in fixed bed micro column It was found that the carbon bed sorption capacity for phenol and chlorophenol (77.20 and 80.0 mg/g) were higher than the equilibrium sorption studies. The critical bed depth increased with increasing phenol and chlorophenol concentrations. An increase in phenol and chlorophenol concentration from 100 to 200mg/l increased the rate constant, critical bed depth (Do) and bed sorption capacity, for phenol 77.20 to 160.00mg/g and chlorophenol 80.00 to 173.20mg/g. The breakthrough time, exhaustion time, uptake capacity decreased as the flow rate increased. Chlorophenol and phenol uptake capacity increased with increase in bed height. Experimental data for the change in concentration were correlated using the bed depth service time (BDST) model. In all parameters determined chlorophenol had better adsorption than phenol. Fluted pumpkin is the largest consumed vegetable in the West African sub region and therefore, creates one of the major agro waste problems in Nigeria. Preliminary investigations showed that several tons of these waste are produced daily in market places around the country but scarcely useful and therefore create environmental nuisance. The results obtained could be useful for the application of agricultural wastes for phenol and chlorophenol removal from industrial wastewater. @ JASEM In the seventies of the last century, the combined global production of phenol and chlorophenols approached 200 million Kg (Atuanya and Chakrabarti, 2003), which has been manufactured in paper, textiles, pharmaceuticals and fertilizer industries. These compounds usually cannot be totally utilised and eventually will be discharged out from industrial processes. Hence a proper waste water treatment method or strategy is needed to tackle industrial effluents. Adsorption has gained increasing popularity in recent years as a unit operation for removing pollutants from effluents (Mall et al., 2006; Wang and Li, 2007), because the process produces a high quality treated effluent which can meet stringent environmental emission standards. In the search for potential low-cost sorbents for pollutant attenuation in aqueous medium, a number of materials have been investigated for their ability for pollutant attenuation. Some of these sorbets are; (cassava waste biomass, tea factory waste, fluted pumpkin stem waste and water spinach (Horsfall et al., 2003; Cay et al., 2004; Ekpete et al., 2010; Tarawou et al., 2010). Although batch systems produce interesting information in the form of isotherms, adsorption columns, simulate commercial and industrial adsorbers and real world environmental solutions. The advantages of a fixed bed system include little operator attention, easy inspection and cleaning for regeneration of adsorbent, and fewer instances of adsorbent particles in the effluent. Disadvantages include the large physical area needed to operate the fixed bed and higher capital investment. Fluted pumpkin (Telfairia occidentalis HOOK F) is a creeping vegetative shrub that spread low across the ground with large lobed leaves and long twisting tendrils. T.occidentalis is grown in some parts of West Africa for its nutritional uses (Horsfall and Spiff, 2005). Several workers have reported the nutritional composition of fluted pumpkin seeds (Fagbemi et al., 2005; Ganiyu, 2005; Agatemor, 2006; Fasuyi, 2008). A single stem with leaves weighing 1.2kg produces less than 200g of leaves, leaving over 1kg stem as waste. Fluted pumpkin is the largest consumed vegetable in the West African sub region and therefore creates one of the major agro waste problems in Nigeria. Preliminary investigations showed that several tons of these waste are produced daily in market places around the country but scarcely useful and there fore create environmental nuisance. Various researches have been conducted for adsorption of phenol and chlorophenol using other adsorbents over the past years. None have been reported on the adsorption of phenol and 2chlorophenol using activated carbon derived from fluted pumpkin stem waste. The objective of the current investigation was to evaluate the sorption of phenol and chlorophenol on to the fluted activated carbon in a downward flow packed bed column arrangement. The effects of design parameters, such as bed height, initial phenol and chlorophenol concentration and flow rate have been investigated. The breakthrough profiles for the sorption of phenol and chlorophenol were analyzed using bed depth service time (BDST) model. MATERIALS AND METHODS The fluted pumpkin stem waste (Telfairia occidentalis Hook F) used for this study was obtained from Iwofe market Rumuolumeni Port Harcourt. The