Preparation of oleophilic perlite by polymer encapsulation

Abstract

A new oil adsorbing material was synthezised' using expanded perlite . To render perlite oleophilic and hydrophobic it was coated with a suitable hydrocarbon polymer. Perlite was first size classified to assure uniformity and purified from metallic oxide impurities by floatation in ether. After evaporation of adsorbed atmospheric water- it kiss coated using different polymers and different methods. Four subtances were chosen for coating: paraffin, polystyrene, high molecular weight polyethtylene and low molecular weight polyethylene. These substances were solvent deposited on perlite usingappropriatesolvents at suitable temperatures and the solvent was subsequently evaporated. Paraffin due to its volatility could be vapor deposited on perlite under vacuum without the use of solvent. Both paraffin and low molecular weight polyethylene were melt deposited on perlite because of their low melting temperatures. Using these techniques samples with various levels of coating of each material were obtained. These samples were then tested for their oil and water adsorption capability. Further they were conpared among themselves with respect to oil adsorption and cost to choose the best adsorbent. A coating method was also chosen to optimize cost and ease o f manufacture using t h e adsorbent with the highest oil adsorption capacity . Reproducility of the above experiments was tested to calculate accuracy and precision of the work performed. The best adsorbent was found t o be the 48 % low molecular weight polyethylene coated perlite obtained by the melt deposition method. The solid material thus prepared adsorbs 7.4 times its weight in liquid oil, no water, and costs about 108 TL/ Kg. Finally the capacity of the 48% low molecular weight polyethylene coated perlite for hydrocarbon vapor adsorption was tested by passing n-heptane saturated a i r through it. The material adsorbed about one to two its weight in gaseous hydrocarbon. The results were as expected : coating perlite with hydrocarbonlike polymers considerably decreased its water affinity and increased tremendously its oil adsorption capacity. This new material can be used as an efficient sorbent for adsorbing oil and other non-polar organic substances from water surfaces and city water, as well as hydrocarbon vapors from flue gases. It can probably be used in any field requiring oil or non-polar substance removal.