Oil separation from oil in water emulsion by coalescence filtration using kapok fibre

In this study, the stable emulsion of engine oil in water of concentration 10% was prepared using a non-ionic surfactant. Kapok fibres were used as filter beds to separate oil from the oil-water emulsion. The surface morphology of fibres was investigated using Scanning Electron Microscope (SEM) analysis and chemical bond analysis of fibres done using Fourier transform infrared (FTIR). Kapok filter beds were prepared with three different bed heights 10, 20 and 30 mm each with four different porosities 0.90, 0.92, 0.95 and 0.98 for preparing the coalescence filter. The oil-water emulsion (influent) was pumped into the filtration column and the coalesced oil droplets, water, as well as un-coalesced oil droplets, especially the finer oil droplets, were collected as effluent. Oil separation efficiency was evaluated in terms of change in droplet size (D50) and oil concentration from influent to effluent. With increasing porosity and bed height, apart from porosity of 0.92, the separation efficiency increases. Increasing the bed heights at lower porosities does not improve the efficiency of the process. A combination of 0.98 porosity and a bed height of 30 mm provided the highest filtration performance in terms of oil separation efficiency and D50 droplet ratio. At 0.98 porosity, increasing the bed height from 10 mm to 30 mm resulted in a D50 droplet ratio of 0.25-0.14, representing a significant decrease in droplet size in the effluent and therefore an increase in oil separation efficiency from 91.3% to 99.63%.

Study of oil sorption behavior of filled and structured fiber assemblies made from polypropylene, kapok and milkweed fibers

This article reports on oil sorption behavior of fiber assemblies made up of single natural and synthetic fibers as well as blend of natural and synthetic fibers when tested with high density oil and diesel oil. A series of filled fiber assemblies were prepared from 100% polypropylene, kapok, and milkweed fibers and another series of bonded structured fiber assemblies were prepared from a 70/30 blend of kapok and polypropylene fibers and a 70/30 blend of milkweed and polypropylene fibers. It was observed that the porosity of the fiber assemblies played a very important role in determining its oil sorption capacity. The polypropylene fiber assembly exhibited the highest sorption capacity (g/g) followed by the kapok and milkweed fiber assemblies at porosity <0.98. At higher porosities (above 0.98), polypropylene filled fiber assembly has poor sorption capacity due to large sized inter fiber pore. The kapok and milkweed fibers have intra fiber porosities of 0.81 and 0.83, respectively. All the fiber assemblies showed higher oil sorption capacity with the high density oil as compared to the diesel oil. As the kapok and milkweed fiber have low cellulose content, hence their slow degradation is an advantage in fresh and marine water applications. The good sorption capacity of kapok and milkweed fiber assemblies along with their bio-degradable nature offer great scope for structuring them into fiber assemblies with large porosity and uniform pores to have efficient oil sorbents.