Speaker
Description
Petroleum industry is the leading domain in certain countries, and at the same time it contributes significantly to environmental pollution due to oil spills and leakage, and presence of refinery products in wastewater. In many regions including Middle East fresh water is scare and requires careful handling and treatment. In this work, we developed a green chitosan-based porous aerogel (sponge) for oil-water emulsions separation and removal of toxic fossil-based pollutants such as chloroform and xylene that are partially soluble in water.
Hydrophobic aerogels were fabricated during two-stages synthesis. First, chitosan was dissolved in acetic acid followed by addition of glycidoxypropyltrimethoxysilane as crosslinking agent. Solutions were freezed at -20°C and then freeze-dried at -80°C. Second, porous aerogels were treated with silanization solution to obtain a hydrophobic surface and functionalize the material. Obtained products were characterized using a set of techniques that confirmed their chemical structure – solid-state 13C-NMR, FTIR, XRD, TGA, BET, and SEM. Wettability of materials was tested with water contact angle measurements. The effectiveness of chitosan aerogel in emulsion separation was examined for direct “oil-in-water” emulsions, using chloroform as the hydrocarbon phase, and aerogel as adsorbent. Emulsions were prepared with an oil-water ratio of 1:9 with deionized water and sweater (57 g/L) and stabilized with different surfactants – nonionic Tween 20 and cationic DTAB. Emulsions were analyzed qualitatively with an optical microscope before and after separation, and quantitatively using GC-FID measurements of chloroform in water.
During development of final product, optimal chitosan-glycidoxypropyltrimethoxysilane molar ratio and composition of coating solution was determined. Characterization with SEM revealed a porous sponge-like texture of the material. Water contact angle values on the aerogels surface varied in the range 130-160°. The results reveal that seawater-chloroform emulsions were less stable that those in deionized water. The material absorbs 28 g/g of pure chloroform within 10 minutes. The highest separation efficiency was achieved for the seawater/DTAB/chloroform emulsion, reaching 98%. Deionized water/DTAB/chloroform emulsion was separated with the efficiency of 85%. High affinity to the hydrocarbon phase allows rapid absorption of the organic phase and only minor interaction with water. In addition, tortuous channels within the structure allow hydrocarbons to be trapped, thereby maintaining the absorption process.
The present study developed a novel material based on chitosan, which is the second most abundant natural polymer on the planet. Fabricated aerogels/sponges can be upscaled until industrial amounts and used as water filters in locations that release oil or its toxic derivatives such as BTEX. The suggested locations include oil fields, refineries, petrochemical laboratories, or small plants.
| Country | Saudi Arabia |
|---|---|
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