| dc.description.abstract | World’s most productive and valuable ecosystem is the wetlands. Quality and functions of wetlands have been
affected adversely by deforestation, fertilizers, and pesticides among others. Pollution by phosphates affect aquatic
life as they have serious side effects at very low levels. Silica molybdate was prepared by first chlorinating silica
sand using phosphorous pentachloride (PCl5) to give chlorinated silica. Amination of chlorinated silica was done
using Ethylenediamine (EDA) and later molybdate was chemically grafted to the aminated silica to yield silica
molybdate. Silica molybdate was used to reduce the levels of PO4
3- residues from wetland ecosystem.. Molecular
structure of the silica molybdate material was characterized using Fourier Transform Infrared (FT-IR). FT-IR results
showed Adsorption bands at 854cm-1 and 542cm-1 which were attributed to Mo=O and Mo-O stretching in
molybdate. Peaks observed at 1388 and 1662cm-1 were attributed with the vibration mode of Mo-OH bond and
bending mode of adsorbed water. Spectra peaks observed at 542, 634.58 and 898.97 cm-1 were attributed to the
adsorption of molybdate. The physical adsorption parameters which were examined using batch adsorption system
were; temperature, pH, contact, time, initial concentration using sorption models, adsorption kinetics and
thermodynamics. Results showed that optimum pH for biosorption of PO4
2- was 6.0, optimal contact time was 30
minutes, optimum temperature was 45 ℃. The experimental results obtained showed that the maximum phosphate
adsorption of silica molybdate was achieved at 194.93mg/g at adsorption optimal conditions of pH, temperature
and contact time. The phosphate removal based on silica molybdate will offer several benefits such as low cost,
effectiveness and reliability to lower the levels of phosphates in wetland waters as compared to commercial
activated carbon. Based on the adsorption efficiency values obtained from this study and comparing them with
adsorption efficiency reported in the literature, it can be concluded that silica molybdate is super adsorbent for the
removal of phosphates from wetland waters. | en_US |
