Department: Chemical Engineering
Ugonabo, V. I.
Onukwuli, O. D.
Coag-flocculation and adsorption of pharmaceutical and vegetable oil waste water were carried out using natural materials. Natural materials such as Corchorus olitorius seed (COSC), Pleurotus tuberregium sclerotium (PTSC), Mucuna prurien seed (MPSC), Telfaria occidentialis seed (TOSC), Maginata achatina shell (SSC), were used as bio-coagulants while Magnifera indica seed (MSA), Treculia africana husks (BFHA), Oryza sativa husks (RHA), Kaolinite(UCA) and Laterite were employed as adsorbents. The characterization of the waste waters, coag-flocculants and adsorbents were carried out following methods of American water works Association (AWWA) and Association of Analytical Chemists (AOAC) etc. The nephelometric bench scale jar test was employed for the coag-flocculation study and subsequently, a multiple batch adsorption program was implemented. The coag-flocculants were prepared following the methods of Gunaratna, et al and Jatto, et al, for seed derived coagulants and Maginata achatina shell, respectively. The adsorbents were produced based on the method of high temperature (300 – 9000C) furnace carbonization of Magnifera indica seed, Treculia africana husks and Oryza sativa husks. The carbonized samples together with kaolinite and Laterite were later activated with sulphuric acid. Factors sensitivity analyses of pH, dosage, settling time, adsorbent mass and stirring time were conducted using one factor at a time (OFAT) and Design of experiment (DOE) methods. For the DOE, the system was subjected to statistical (23 Central composite Design CCD) modeling for optimization purposes. Results obtained from coag-flocculants characterization showed that, the percentage protein content, being the coag-flocculation active agent in PTSC, MPSC, SSC, COSC and TOSC were 43.70%, 40.75%, 38.50%, 29.57% and 27.00% respectively. PTSC had the highest percentage of protein content of all the coag-flocculants used. The maximum coag-flocculation performance was recorded for PTSC at the rate constant K of 2.491E-04l/g.min, coagulation period 1/2 of 0.07min, coag-flocculation efficiency E(%)> 92% at the optimum dosage of 0.2g/l and pH of 10 . Fourier transform infrared spectra of the activated carbon and non-carbons show a number of discernable peaks, depicting the complex bio-mass structure and numerous functional groups (such as – OH, C = O, C – H, Si-O-Si, AI-O-H and Si-O) that favored the adsorption of the colloidal particles. The X-ray diffraction pattern for all the adsorbents (BFHA, RHA, LATERITE, UCA, MSA) shows that quartz, silicate, alumina and kaolinite were major constituents though other element such as zaherite, magnesium, Lithium etc were in trace quantities. Scanning electron micrographs of samples show extensive widened pores and morphological changes in particle geometry of the adsorbents, which were more pronounced in activated carbons, indicating that the carbon particles were in the form of spherical pores with a range of sizes. Adsorbents characterization results shows that activated carbon from Magnifera indica seed (MSA) had the highest value of surface area (adsorption capacity determinant) and total pore volume of 1658.00cm2/g and 0.6600, respectively. For MSA, the maximum percentage adsorbate removal were recorded for pH, adsorbent mass, stirring time and removal efficiency at 2, 1.0g, 60min and (97.366% pharmarceutical industry effluent(PIE) and 93.8182% vegetable oil industry effluent(VIE) The adsorption data best fitted to Freundlich isotherm model, while the data was best described by Temkin isotherm model. Pseudo second order best described the kinetics of the adsorption process. The calculated values of G0, H0, and S0, indicates the spontaneous and endothermic nature of the reaction and increased randomness of the adsorbates at the solid-solution interface.