IRSPAS 2017
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Item Equilibrium studies on the adsorption of heavy metals, dyes and phenol by phosphoric acid modified rice husk.(International Research Symposium on Pure and Applied Sciences, 2017 Faculty of Science, University of Kelaniya, Sri Lanka., 2017) Parthiban, G.; Rifna, M. S. F.The removal of contaminants from wastewater is still far away from a satisfactory solution. In fact, the selection of a particular wastewater treatment technology should not be based uniquely on its efficiency, but should rather integrate environmental and economical aspects. Within this framework, the main objective of this study is the removal of various contaminants in wastewater including heavy metals (Cadmium and Copper), dyes (Methyl Red and Methylene Blue) and Phenolic compounds via an environmental friendly green technology method. In this study, grounded rice husk was examined as sorbent material which was chemically modified with Phosphoric acid (1.0 M) and was found to be effective in removing the contaminants. Batch studies were performed on synthetic wastewater at room temperature to evaluate the effects of various parameters such as contact time, pH, initial concentration of the solution and adsorbent dose on removal efficiency of the pollutants. The experiment was also applied to treat two samples of industrial wastewater containing Cadmium and Carmoisine E122. The removal efficiency was found to be pH dependant. The removal efficiency was higher for Phenol and Methyl Red at low pH values and it was shown that the removal efficiency was higher for heavy metals and Methylene Blue at higher pH values. The equilibrium was reached approximately in 2 hours for all the contaminants. Equilibrium sorption data were fitted into Langmuir, Freundlich, Temkin and Dubinin-Radushkevich (D-R) isotherms. Of the four adsorption isotherms, the R2 value was higher for D-R isotherm for the adsorption of Cadmium (0.979), Freundlich and Temkin isotherms for the adsorption of Copper (0.945), Freundlich isotherm for the adsorption of Methyl Red (0.994), Temkin isotherm for the adsorption of Methylene Blue (0.953) and Langmuir isotherm for the adsorption of Phenol (0.987). Adsorption data were well described and adsorption isotherm constants were determined from the respective adsorption isotherm equations. The present study analyzed the adsorption of rice husk and concluded that treated rice husk gave comparatively better adsorption efficiency. The treated rice husk can be implemented on large scale industrial applications after field studies.Item Development and application of rice-straw biochar for removal of selected heavy metals (Pb, Cd and Cr) in contaminated paddy soil.(International Research Symposium on Pure and Applied Sciences, 2017 Faculty of Science, University of Kelaniya, Sri Lanka., 2017) Irosha, K. P. C.; De Silva, D. S. M.Biochar which is derived from carbon rich biomass such as wood, manure and leaves, is increasingly recognized as multifunctional material for various applications like contaminant management in soil and water, soil amendment in agriculture etc. In this study, rice-straw derived biochar was produced at a temperature of 400 ºC in the presence of concentrated H3PO4. The resulted biochar was subjected to oxidation by different agents including KOH, HNO3 and H2O2 to enhance its adsorption properties. The pore size distribution of modified, non-modified and commercial biochar types was studied using scanning electron microscope (SEM) technique and functional group analysis was carried out using the Fourier transform infrared spectroscopic (FTIR) technique. The FTIR spectroscopic analysis revealed significant increase in concentrations (based on peak area with constant amount of samples) of the functional groups such as carboxylic, alcoholic hydroxyl, phenolic hydroxyl and carbonyl groups available on the surface of the KOH treated sample. The SEM analysis revealed about 40% increment in pore diameter of the rice straw biochar that was modified with KOH. The paddy soil sample analyzed was amended with known amounts of heavy metal (Pb, Cd, and Cr) containing salts prior to analysis. To study the heavy metal adsorption capacity of modified, non-modified rice straw biochar and commercial biochar types, biochar (5 g x 7) which were packed and sealed in cellulose bags (5 x 5 cm2) were introduced to the soil samples (3 kg in a side sealed rain-gutter). All the experiments were performed in triplicate. The amounts of heavy metals in amended soil, after treating with biochar, and adsorbed by biochar were measured using Atomic absorption spectroscopic (AAS) technique. The AAS study revealed that all modified rice straw biochar types adsorbed heavy metal ions more efficiently than its non-modified counterpart. Further, this analysis revealed that H2O2 treated biochar is more likely to adsorb Pb and Cd, while the KOH treated biochar is more suitable for Cd and Cr adsorption.Item Assessment of polycyclic aromatic hydrocarbons and heavy metals in the vicinity of an oil refinery in Sri Lanka using moss as a bioindicator.(International Research Symposium on Pure and Applied Sciences, 2017 Faculty of Science, University of Kelaniya, Sri Lanka., 2017) Nirmani, L. P. T.; Deeyamulla, M. P.Polyaromatic hydrocarbons (PAHs) and heavy metals are toxic compounds emitted from various anthropogenic sources and have a great effect on the human health as well as on the environment. Population living closer to the vicinity of an oil refinery may be at a greater risk of exposure to PAHs through inhalation, ingestion, and direct contact with the contaminated media. Atmospheric deposition of pollutants occur through both wet and dry deposition. Biomonitoring agent and passive monitoring technique were used in this study to evaluate heavy metal and PAH content in moss (Hyophila Involuta) collected from 30 sampling sites around the Sapugaskanda oil refinery with a 5 km radii. Sample collection was carried out in two separate days in September 2016. This study aimed to obtain a possible correlation between the atmospheric deposition of heavy metals and radial distribution pattern using epiphyte mosses collected from each sites. 16 PAHs were identified and quantified using High Performance Liquid Chromatography (HPLC). Bioaccumulation ability of seven heavy metals (Cr, Ni, Cd, Cu, Pb, Fe and Zn) were evaluated by Ion coupled plasma mass spectroscopy (ICP – MS). Contamination factor (CF) and Pollution loading index (PLI) were determined with reference to the background heavy metal concentration values. Maximum heavy metal accumulation was observed in a 2 km radii from the oil refinery. All the sampling sites showed CF>1 except for heavy metals Cr and Cd in few sampling sites. Pollution loading index for each radius showed a higher value with reference to the background levels. Low molecular weight (LMW) PAHs move away from the source (Sapugaskanda refinery) and high molecular weight (HMW) PAHs deposit near the emission source. Total concentration of carcinogenic PAHs varied from 0.25 to 13.75 ng/g. According to the study, total PAHs deposition observed around the vicinity of the oil refinery was in the range of 20 – 4398 ng/g. Due to the similar pollution sources, PAHs have often been found to coexist with environmental pollutants including heavy metals. Correlation studies were carried out statistically. There was a positive correlation between the Fe with Low molecular weight Polyaromatic hydrocarbons (LMW PAH) and High molecular weight polyaromatic hydrocarbons (HMW PAH) (p< 0.05). There were few correlations among several metals. Fe showed a positive correlation with metals such as Ni, Cu and Cd whereas Ni showed positive correlation with Cu and Cd. There was no significant correlation among other metals and PAHs. (p> 0.05).