A Dried Hydrophobic Aquaphyte as an Oil Filter for Oil/Water Emulsions

In the present study, dead biomass derived from a hydrophobic aquatic plant, a Salvinia sp. found in Southern Brazil, was studied as an oil filter for oil/water emulsions. The performance of the Salvinia sp. biomass as such was compared to that of a processed peat (Peat Sorb) that is sometimes used as a sorbent for oil. In the utilization of the Salvinia sp. and Peat Sorb as filters for oil in oil/water emulsions the results of two equal tests were averaged in order to verify the reproducibility of the experimentation. In the experiments the emulsion was passed through the filters until saturation of the filter was indicated by the appearance of oil in the filtrate (breakthrough). For Salvinia sp., the average amount of emulsion passed through the filter until breakthrough was 18.7 l containing 10.61 g oil. The amount of oil retained was 9.53 or 1.33 g oil/g biomass. Thus, 90% of the oil in 18.7 l emulsion was retained by the biomass. The tests using Peat Sorb were performed under the same conditions as for the aquaphyte biomass. The average amount of emulsion passed through the filter until breakthrough was 4.0 l containing 2.68 g oil. The amount of oil retained was 1.66 or 0.26 g oil/g Peat Sorb. Thus, the Peat Sorb retained 62% of the oil in 4.0 l emulsion. The superiority of the Salvinia sp. for removing oil from such emulsions, since the surface areas of the two materials are similar, appears to be due to the hydrophobicity and the hair like projections of the surface of the aquaphyte biomass.