Browsing by Author "Rajapaksha, AU"

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    Preparation and characterization of dendro biochar-hydroxyapatite composite: a potential material for defluoridation
    (IEEE, 2021-07) Rathnayake, A; Hettithanthri, O; Rajapaksha, AU; Vithanage, M; Adhikariwatte, W; Rathnayake, M; Hemachandra, K
    Hydroxyapatite (HAP) is a recognized material for fluoride adsorption; however, dissolution in acidic pH is a disadvantage, while dendro biochar (DBC) is a byproduct from dendro power plants in Sri Lanka. The objective of this study was to synthesize dendro biochar-hydroxyapatite (DBC-HAP) composite to reduce HAP dissolution and improve biochar's capacity for fluoride removal. Then it was characterized toward an enhanced fluoride removal in water. DBC-HAP composite was synthesized by the co-precipitation method. Pristine and composite materials were characterized using point of zero charge (pH PZC ), Fourier Transform Infrared spectroscopy (FTIR), X-ray Diffraction (XRD) and Thermogravimetric analysis (TGA) to understand its potential for fluoride removal. The pH PZC for DBC, HAP and DBC-HAP were 10.39, 6.82 and 8.52 respectively. The surface charge of DBC-HAP composite was reduced by a pH of 1.87 compared to DBC. FTIR bands confirmed mineralized functional groups such as Ca 2 + and −OH in the composite, which can facilitate defluoridation. XRD analysis indicated enhanced crystalline properties of the composite compared to DBC. TGA results exhibited changes in thermal stability for the composite compared to HAP. Overall characterization results of the DBC-HAP composite indicated the features of a low-cost, easily synthesizable defluoridation material.
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    Propensity and appraisal of biochar performance in removal of oil spills: A comprehensive review
    (Elsevier, 2021) Madhubashani, AMP; Giannakoudakis, DA; Amarasinghe, BMWPK; Rajapaksha, AU; Kumara, PBTP; Triantafyllidis, KS; Vithanage, M
    Recently, the adsorption-based environmental remediation techniques have gained a considerable attention, due to their economic viability and simplicity over other methods. Hence, detailed presentation and analysis were herein focused on describing the role of biochar in oil spill removal. Oil removal by utilizing biochar is assumed as a green-oriented concept. Biochar is a carbon-rich low-cost material with high porosity and specific surface chemistry, with a tremendous potentiality for oil removal from aqueous solutions. Oil sorption properties of biochar mainly depend on the biochar production/synthesis method, and the biomass feedstock type. In order to preserve the stability of functional groups in the structure, biochar needs to be produced/activated at low temperatures (<700 ᵒC). In general, biochar derived from biomass containing high lignin content via slow pyrolysis is more favorable for oil removal. Exceptional characteristics of biochar which intensify the oil removal capability such as hydrophobicity, oleophilicity or/and specific contaminant-surface interaction of biochar can be enhanced and be tuned by chemical and physical activation methods. Considering all the presented results, future perspectives such as the examination of biochar efficacy on oil removal efficiency in multi-element contaminated aqueous solutions to identify the best biomass feedstocks, the production protocols and large-scale field trials, are also discussed.