[1] Univ Malaya, Dept Chem Engn, Kuala Lumpur 50603, Malaysia
[2] Univ London Imperial Coll Sci Technol & Med, Dept Chem Engn, South Kensington Campus, London SW7 2AZ, England
[3] UCSI Univ, Chem & Petr Engn Dept, Fac Engn Technol & Built Environm, Kuala Lumpur 56000, Malaysia