Preparation and Characterization of Tertiary Amine Functionalized MCM-41 for the Removal of Nitrate from Aqueous Solution

Nitrate is known as one of the major pollutants in water. The presence of nitrate in water together with phosphates, pesticides and heavy metals create public health and environment hazards because it enhanced the growth of algae and causes depletion of dissolved oxygen. Nitrate is a stable and highly soluble ion with low potential for co-precipitation or adsorption, thus making it difficult to be removed from water. Scientists and technologists have been doing numerous researches to invent the best nitrate removal processes. Among them, adsorption methods are favorable due to its simple application and economical operation because sludge production and disposal issues are at minimal. Amine functionalized mesoporous silica represents one of the potential adsorbents offering an opportunity to remove nitrate ions from aqueous solutions. Some successful studies have been done by applying primary amine-functionalized mesoporous silica, APTMS MCM-41 as adsorbents and 40% percentage removal was achieved. The aim of this research project is to study the nitrate removal efficiency by using tertiary amine functionalized, AEPTMS MCM-41 as adsorbents at different percentage loading of tertiary aminosilanes group. The preparation of the samples was done by using co-condensation method. The experimental work was carried out by mixing the functionalized samples with nitrate solution at different initial nitrate concentrations and time duration in order to perform kinetics and isotherms study. Absorbance of the final nitrate solution was analyzed by using UV-Vis spectroscopy. Based on the results obtained, the percentage removal of nitrate from sodium nitrate solution increases with increasing loading of tertiary aminosilanes group in the samples. Kinetic study showed that the kinetic data follows Pseudo-second order model while for isotherm study, the isotherm data of MCM-41 loaded with 10% and 20% AEPTMS fitted well by using Langmuir isotherm model while the pure MCM-41 fitted by Freundlich isotherm model. Sample characterization by using FTIR spectroscopy proved the presence of aminosilane group (N-H) in the sample.