Cornelius Tsamo, Miss Tjilha Etienne Hervé, Abba Paltahe, Djorwe Bonga
A natural soil rich in allophane was tested as adsorbent for the removal of phosphate ions from aqueous solution. The soil was characterized using particle size distribution, EDS, FTIR, XRD, TGA, and Nitrogen adsorption-desorption analyses. The effects of contact time, pH, initial concentration, adsorbent dose, and temperature and co-ions on adsorption were performed. The soil is Si-allophane rich as Al:Si is 1.03. It has a BET surface area of 41.7112 m²/g, total pore volume of 0.101018 cm³/g and average pore width of 96.8741 Å with over 80% particles having sizes <100µm. Nearly 100% of the phosphate was removed in 5 minutes. There is a strong linear relationship between amount adsorbed and initial concentration due to the ability of the adsorbent to generate more adsorption sites with increase loading. About 1000 mg/g was adsorbed for 0.05 g of adsorbent. This high affinity is illustrated by Langmuir equilibrium constant (b) value of 2000 L/mg, the Jovanovic constant (𝐾𝐽) of 0.002 and the ∆S° value of + 0.048 KJ/mol K. chloride and sulphate ions inhibits phosphate removal, but bicarbonate ions enhance phosphate removal. The phosphate removal is also enhanced with the simultaneous presence of cations and anions at low and elevated concentrations. The tested Si-rich allophane soil, which is cheap, locally available and needing no treatment is very effective in removing phosphate ions from wastewater.
Allophane, Soil, Phosphate, Adsorption, Co-ions, Isotherms
Cite this paper
Cornelius Tsamo, Miss Tjilha Etienne Hervé, Abba Paltahe, Djorwe Bonga. (2020) Local Si-allophane Rich Soil Adsorbent for Phosphate Removal From Synthetic Wastewater: Equilibrium, Kinetic, Thermodynamic and Co-ions Studies. International Journal of Chemistry and Chemical Engineering Systems, 5, 16-33