Activated Carbon Adsorbent Porosity and Loading Factor Effects on the Adsorption Efficiency of Groundwater Treatment System for Crude Oil Hydrocarbons and Solid Metals Impurities Recovery in Niger Delta Region (Published)
Despite how large hydrosphere tends to occupy the earth (70%), unavailability of useful industrial and domestic water (especially within oil producing countries) happens to be increasing daily, proportional to increase in population density, industrialization, poor wastes management and fossil fuel processing, which promotes hydrocarbons and solid metals contaminants deposition within human environments, with high potency of altering surface and groundwater quality, making water treatment using adsorbent such as activated carbon (AC), a most recommended measure. This work focus on assessment of AC porosity and loading factor effects on crude oil hydrocarbons and solid metals recovery efficiency of an adsorption system using Niger Delta regions groundwater as adsorbate medium. Coconut shells activated carbon (CSAC) were produced at different carbonated temperatures of 500oC, 700oC and 900oC, and their porosities as function of the monolayer capacity () were equally determined using the LBET analytical tool. After which the CSACs were used in treatment of hydrocarbon based contaminated groundwater of Okrika LGA (Niger Delta region of Nigeria), at different packed bed adsorbent loading factor (ALF): 100% CSAC-500oC, 100% CSAC-700oC, 100% CSAC-900oC, 50:50% CSAC-500oC:700oC and 50:50% CSAC-500oC:900oC. The LBET analytic results identifies CSAC-500oC adsorbent to be of 0.0485 intercept and 751.8797 Kpag/cm3 monolayer capacity (), while CSAC-700oC shows intercept of 0.0485 with 1086.9565 Kpag/cm3 , then CSAC-900oC. shows intercept of 0.0225 and of 1250 Kpag/cm3 which depicts a higher porosity. The LBET result was able depicts that increase in carbonation temperature of an AC promotes the increase in the adsorbent porosity. Also, the treatment result using hydrocarbon contaminated ground water identifies the 900oC carbonated AC to be of higher recovery efficiency (86.85%) on solid metals and BTX recovery from Okrika groundwater, such that groundwater consisting Benzene, Toluene, o-Xylene, m-Xylene, p-Xylene, and Ethylbenzene aromatic compounds at 29.63721 ppm, 36.48904 ppm 19.32716 ppm, 15.56647 ppm, 12.29102 ppm, and 27.81541 ppm contaminant level respective, was treated to 6.26581 ppm, 7.90743 ppm, 1.25129 ppm, 0.0000 ppm, 0.0000 ppm, and 0.61832 ppm using the 900oC produced CSAC, while that of the 700oC reduced the aromatics to 10.78562 ppm, 12.90318 ppm, 5.32647 ppm, 1.28593 ppm, 0.000 ppm, and 4.93820 ppm, and that of 500oC reduced them to 13.85162 ppm, 17.90648 ppm, 8.61773 ppm, 4.37570 ppm, 1.54382 ppm and 11.91048 ppm, which are (700oC and 500oC CSAC) both less efficient compared to that achieved by the used of CSAC-900oC. Also, the reactor adsorption performance proves to be more effective in using a combined ALF approach with 50:50 loading factor of 500oC – 900oC-CSAC most efficient in treatment of the hydrocarbon contaminated water, such that the untreated groundwater Benzene, Toluene, o-Xylene, m-Xylene, p-Xylene, and Ethylbenzene levels depleted to 2.51623 ppm, 3.40394 ppm, 0.0000ppm, 0.0000 ppm, and 0.0000ppm, 0.0000 ppm respectively when assessed. It’s concluded that high carbonation temperature of adsorbent increase adsorbent porosity, which proportionally increases the adsorbent efficiency over reactor resident time of the studied system. Also, a combined ALF approach is most appropriate for effective water treatment.
Keywords: Oil-spillage, adsorbent loading factor (ALF), carbonation temperature, contaminates recovery factor, groundwater treatment, langmuir adsorption model, water pollution