UV/VIS characterization and FT-IR analysis of harmattan dust across Sub-Sahara Region of Africa

Abstract

The suspended dust particles that blow across Nigeria as a result of north-east trade wind emanating from the Sahara desert annually are locally referred to as Harmattan. Suspended dust samples were collected across ten different stations in Nigeria; namely: Maiduguri (11º49'N, 13º09'E), Potiskum (11º43'N, 11º02'E), Bauchi (10º17'N, 09º 48'E), Jos (9º55'N, 8º55'E), Lafia (08º49'N, 07º50'E), Abuja (09º09'N, 07º11'E), Minna (9º36'N, 06º35'E), Ilorin (8º36'N, 4º 35'E), Oyo (8º12'N, 3º42'E) and Iwo (7º63'N, 4º19'E) and analyzed using Fourier Transform Infrared (FT-IR) and UV-Visible spectroscopy. The quantitative, qualitative and optical characterization analyses were carried out on all the samples collected across all the stations considered, in order to obtain the functional groups and some elements present in the samples. The FT-IR spectra peaks show that the transmittance waveband from 3337.8 cm-1 to 3291.2 cm-1 corresponds to the Hydroxyl group, H-bonded OH stretch in plane and out of plane bonds for all the stations considered. These bonds represent the presence of transition metals and unsaturated bonds found in the samples, which include K, Ca, Ti, Mn, Fe, Ni, Cu, Zn, Mo, As, Zr, Pb, V, Sr, Cr and Ce. The samples collected across all stations have maximum UV absorbance peaks at around 210 nm waveband and weak visible light absorbance peaks (orange – red spectra) around 620 nm and 700 nm. The study concluded that the transmittance waveband, the waveband absorbance peaks and the elemental composition of the dust samples analyzed vary from station to station. This study will however recommend that further study be made for the purpose of environmental awareness.