African black velvet tamarind (Dialium guineense) as a green adsorbent for groundwater remediation

Abstract

Process shells of black velvet tamarind fruits was investigated as an adsorbent for the potential removal of the pollutant heavy metal ions of Fe, Cr, Pb, Mn and Zn in well water samples collected from six different locations in Enugu Metropolis, Eastern Nigeria. Fourier Transform Infra-Red Spectroscopy absorption bands characteristic of stretching, scissoring and bending vibrations of - O-H groups of alcohols (R-OH) and phenols (Ph-OH), Sp3 (–C-H) of an oxygen bonded carbon atom, –C-O-C- bond and Sp2 (---C==C—H) carbons in a ring structure were seen between 3400 to 3200 cm-1, 1438 to 1371 cm-1, 2922/2851 cm-1 and 1155/1028 cm-1 as well as the 1509 cm-1 in the infra-red region of the electromagnetic spectrum in the infra-red absorption spectrum of processed black velvet tamarind fruit shells. Metal ion analysis was carried out by Flame Atomic Absorption Spectroscopy. The results showed that the adsorbent removed 40.50 to 63.30, 33.33 to 52.63, 26.23 to 48.05 and 15.00 to 37.84% respectively of Fe, Zn, Cr and Mn in the well water samples but was ineffective in removing Pb. This demonstrates the usefulness of black velvet tamarind fruit shells in decontaminating heavy metal burdened water and suggests that the technique has potential to reclaim polluted water of such nature, ameliorate the problems of insufficient potable water and waste disposal as well as protect the environment from heavy metal pollution.