The focus of this research was to synthesize novel clay-biochar composites by incorporating montmorillonite (MMT) and red earth (RE) clay materials in a municipal solid waste (MSW) biochar for the adsorptive removal of tetracycline (TC) from aqueous media. X-ray Fluorescence Analysis (XRF), Fourier Transform Infrared Spectroscopy (FTIR), Powder X-ray Diffraction (PXRD) and Scanning Electron Microscopy (SEM) were used for the characterization of the synthesized raw biochar (MSW-BC) and clay-biochar composites (MSW-MMT and MSW-RE). Results showed that minute clay particles were dispersed on biochar surfaces. The FTIR bands due to Si-O functional group vibrations in the spectra of the clay-biochar composites provided further evidence for successful composite formation. The kinetic TC adsorption data of MSW-MMT were well fitted to the Elovich model expressing high surface activity of biochar and involvement of multiple mechanisms in the adsorption. The kinetic TC adsorption data of MSW-BC and MSW-RE were fitted to the pseudo second order model indicating dominant contribution of chemisorption mechanism during the adsorption. The adsorption differentiation obtained in the kinetic studies was mainly due to the structure of the combined clay material. The adsorption isotherm data of all the adsorbents were well fitted to the Freundlich model suggesting that the adsorption of TC onto the materials occurred via both physisorption and chemisorption mechanisms. In comparison to the raw biochar and MSW-RE, MSW-MMT exhibited higher TC adsorption capacity. Therefore, MSW-MMT clay-biochar composite could be applied in the remediation of TC antibiotic residues in contaminated aqueous media.
The island nation of Sri Lanka became a plantation economy back in the 19th and 20th centuries,and a significant number of farmers’ livelihoods still depend on agriculture itself. With the low cost of transportation and high solubility, urea fertilizer is leading the industry of agriculture. The current local urea demand is completely met by importations. A constant supply of Natural Gas (NG) is essential to manufacture urea locally. This study mainly focuses on introducing a viable solution for completely importing urea using indigenous gas in place. Amongst the discoveries made around the country, the Dorado reservoir exhibits high quality with a clean, thick deposition. In order to assess the feasibility, the reservoir potential was reviewed and production and supply profiles of NG were analysed by acquiring data regarding local demand quantities. A cost benefit analysis of establishing a urea plant was prepared with the involvement of a German organization. Previously identified economical quantity and price was applied to the Fiscal Regime for the Dorado reservoir with the assistance of PRDS and three case scenarios were proposed. The cases involve developing NG by the investing company with the most economical gas rate identified,i.e., 70 MMScf/d, where around 20 MMScf/d of it will be utilized to manufacture urea. The excess production of NG will either be sold to the government or integrated to a power plant, which is preferred as it introduces additional benefits to the economy. Further analysis can be made depending on different modes and methods of transporting NG and locations of the plants which can manipulate the costs with better focus on achieving higher yield.
The technology of Sodium ion battery is expected to replace Lithium-ion battery in near future. The chathodes of Lithium-ion battery are prepared using transition metal composites such as oxides, phosphates and silicates and Sodium-ion batteries are also being tested using such composite chathodes. However, these designed cathodes for sodium-ion batteries show a less capacity. This research was conducted in order to prepare a suitable cathode for a sodium-ion battery. The material was formed through a solid-state reaction of sodium phosphate and copper iodide. The composite which was expected to be formed was sodium copper phosphate. The chathode of the battery was fabricated using mixture of active material, activated carbon and polyvinylidene fluoride (PVDF). Cathode was prepared on an aluminum foil and anode was sodium pressed on a copper plate. The synthesized Material was characterized using powder X-Ray Diffraction (XRD) method. Energy Dispersive X-Ray Analysis (EDEX) was performed in order to identify the chemical composition. Charge discharge curves and cyclic voltammetry was taken to characterize the electrochemical properties of the cell. XRD pattern and EDEX results confirmed that the desired composite was formed. The discharging capacity of the battery was calculated to be 103.12 mA h g-1. The cyclic voltammetry analysis has shown that an oxidation and reduction process occurred while charging and discharging.
In exploration geophysics, seismic surveys and their interpretations provide the most reliable information of the subsurface structures. Extensive work on the determination of the subsurface structure has been carried out in both Cauvery and Mannar basins of offshore Sri Lanka. Freely available satellite- gravity and magnetic data suggest that the Lanka Basin may have the necessary sediment volume for the occurrence of hydrocarbons. However, without seismic data, this suggestion cannot be tested further. As an alternative to acquiring additional seismic data in the region, this research focused on digitising 50,000 km of vintage seismic lines from the National Geophysical Data Centre (NGDC) data repository and converting them into Seg-Y format. Key seismic horizons on the digitised sections were interpreted to provide details of the seabed and acoustic basement in the time domain. Regional sedimentary thickness maps were compiled in the time domain interpolating the interpreted horizons using ‘kriging’ method. The velocity data acquired in the region were used to convert the maps from time to depth domain. The results indicate that average thickness of sediments in the region varies around 5000 m to 6000 m, where the maximum thickness is around 8000 m in the North Eastern part of the Lanka basin. The thickness maps can be used as a reference dataset to plan commercial seismic surveys in the future for hydrocarbon exploration in the Lanka Basin.
In this paper, we investigate the release of heavy metals from sludge produced from an electrical industry using both organic and inorganic acids. Single and sequential extractions were conducted to assess heavy metals in different phases of the sludge. Metal release from sludge was investigated in the presence of three inorganic acids (nitric, sulfuric, and phosphoric) and three organic acids (acetic, malic, and citric) at concentrations ranging from 0.1 to 2.0 mol L−1. Sequential extraction indicated the presence of Cu primarily in the carbonate fraction, Pb in the residual fraction, and Ni in the FeMn oxide fraction. The cumulative release rates of heavy metals (i.e., Pb, Cu, and Ni) by 1.0 mol L−1 of acid increased with the use of the following acids in the order of: malic < sulfuric < acetic < phosphoric < citric < nitric. Acetic acid exhibited the highest release of Cu, at a rate of 72.62 × 10−11 mol m−2 s−1 at pH 1, and malic acid drove the release of Pb at a maximum rate of 3.90 × 10−11 mol m−2 s−1. Meanwhile, nitric acid provided the maximum rate of Ni release (0.23 × 10−11 mol m−2 s−1) at pH 1. The high rate of metal release by organic acids is explained through ligand-promoted mechanisms that enhance the release of metal ions from the sludge. The results from our study emphasize that an understanding of the metal release mechanism is key to selecting the optimal acid for the maximum recovery of heavy metals.