Characterization of acid tar waste from benzol purification

The use of concentrated sulphuric acid to purify benzene, toluene and xylene produces acidic waste known as acid tar. The characterization of the acid tar to determine the composition and physical properties to device a way to use the waste was done. There were three acid tars two from benzene (B acid tar), toluene and xylene (TX acid tar) purification streams and one which was from the storage tank (HT acid tar). The viscosity and density varied greatly amoung the three acid tars with B acid tar having the lowest viscosity (28.3mPa.s) and HT acid tar having the highest viscosity (63.592Pa.s). For density HT had the lowest (1.43g/ml) and TX had the highest (1.549g/ml). The sulphuric acid % concentration was 15.4% for HT, 23.7% for TX and 24.2% for B acid tar. The solubility test also showed a difference in the three acid tars, B acid tar was more soluble in water than in methanol while the other two were more soluble in methanol than in water. GC MS and FT-IR results showed that TX and HT acid tars had weak organic acid such carboxylic acid, alcohols and aldehydes. The B acid tar had few organics as compared to TX and HT. The results show that the sulphuric acid is being lost in the holding tank and the physical and chemical properties of B and TX acid tar are different thus the need to treat differently if they are to be treated separately. The HT acid tar has properties that make it easier to work with; an example is the high viscosity and the high organic content.Keywords: Acid tar, benzol processing, sulphuric acid, organic acids, characterization and viscosit

Activated carbon from baobab fruit shells through domestic processes

Surface and groundwater pollution is rampant due to poor waste management and runoff. Dry regions of the country also writhe from water scarcity which leaves communities to resort to unsafe water supplies for domestic use. It is estimated that about 90% rural households in Zimbabwe consume untreated water (Hoko, 2005) and that more than 75% of Zimbabwe's population lives under water stressed conditions in most rural areas (Manyanhaire et al., 2009). Commercially produced activated carbon is expensive. The aim of the research was to investigate the production of activated carbon from baobab fruit shells (a cheap raw material) using a method that can be employed at rural homesteads in removing organic pollutants. Two methods of producing activated carbon were also compared i.e. activating before carbonization and activating after carbonization. Activating with salt after carbonization proved to be the efficient (adsorption% 93.2). A contact time of 60 minutes was determined as the maximum time required for adsorption and a pollutant concentration equivalent to 0.3M oxalic acid gave the highest adsorption of 98.9%. The activated carbon from baobab fruit shells follows a Langmuir isotherm which explains the existence of a monolayer and the saturation of adsorption sites on the activated carbon. It was concluded that activated carbon from baobab fruit shells have the potential of removing organic pollutants from water.Keywords: activated carbon, percentage adsorption, carbonization, adsorption, organic pollutants and fruit shell

The case for a 3rd generation supraglottic airway device facilitating direct vision placement

Although 1st and 2nd generation supraglottic airway devices (SADs) have many desirable features, they are nevertheless inserted in a similar ‘blind’ way as their 1st generation predecessors. Clinicians mostly still rely entirely on subjective indirect assessments to estimate correct placement which supposedly ensures a tight seal. Malpositioning and potential airway compromise occurs in more than half of placements. Vision-guided insertion can improve placement. In this article we propose the development of a 3rd generation supraglottic airway device, equipped with cameras and fiberoptic illumination, to visualise insertion of the device, enable immediate manoeuvres to optimise SAD position, verify whether correct 1st and 2nd seals are achieved and check whether size selected is appropriate. We do not provide technical details of such a ‘3rd generation’ device, but rather present a theoretical analysis of its desirable properties, which are essential to overcome the remaining limitations of current 1st and 2nd generation devices. We also recommend that this further milestone improvement, i.e. ability to place the SAD accurately under direct vision, be eligible for the moniker ‘3rd generation’. Blind insertion of SADs should become the exception and we anticipate, as in other domains such as central venous cannulation and nerve block insertions, vision-guided placement becoming the gold standard