[1] Univ Putra Malaysia, Inst Math Res INSPEM, Serdang 43400, Selangor, Malaysia
[2] Univ Putra Malaysia, Fac Sci, Dept Phys, Serdang 43400, Selangor, Malaysia
[3] Univ Putra Malaysia, Fac Sci, Dept Chem, Serdang 43400, Selangor, Malaysia
[4] Univ Putra Malaysia, Fac Environm Studies, Dept Environm Sci, Serdang 43400, Selangor, Malaysia