No abstract

Today, owing to the environmental and health drawbacks associated with synthetics dyes, stringent standards are imposed by many countries including Mauritius. Following this issue, great enthusiasm is evoked in the rival of natural colourants which are nowadays gaining popularity due to their green approach. Two well-known, readily available and low cost natural dyes bearing plants in Mauritius namely beetroot (Beta Vulgaris) and turmeric (Curcuma Longa) were opted in this study. A comparative study between the extraction of betalains and curcuminoids from the two plants were systematically evaluated between conventional magnetic stirring (MS) and novel microwave assisted extraction techniques (MAE). The optimum operating conditions to yield maximum hues from the two plant species were 50 % aqueous ethanol, agitation speed of 160 rpm, microwave power of 320 W, particle sizes of 0.45 mm and a solid to solvent ratio (SSR) of 1/35. Under the optimised conditions, the results demonstrated that the extraction yields for MAE were higher and more efficient than the conventional one. Consequently, for MS extraction of beetroot and turmeric, the maximum yields recovered were 69.55 % and 48.00 %, whilst the yield for MAE extraction rose to 89.64 % and 79.73 % respectively. Using the experimental data, this research also explored Peleg's and Elovich's kinetic models of dyes extraction.

Faced with demographic explosion and fuelled by its endeavours to become developed, Mauritius has seen a hike in its electricity consumption pattern. The bulk of electricity is generated by burning solid fuels which are namely coal and sugarcane bagasse. Consequently, ash is produced as waste product. Till date, both coal and bagasse ashes are being disposed of in a very unsustainable manner. Due to the availability of numerous studies on coal ash, focus has been laid on bagasse ash. This study analyses the possible ways of valorising bagasse bottom ash (BBA) and bagasse fly ash (BFA) better suited for the Mauritian context. A series of laboratory tests namely moisture content (MC), pH, electrical conductivity (EC), loss on ignition (LOI) and monitoring of the leaching behaviour of phosphate and nitrate were carried out. To monitor the leaching behaviour of nitrate and phosphate, a leaching model has been developed. Following the experimental analysis, several potential utilisation are put forward.