Nitrate removal from aqueous solution by glucose-based carbonaceous adsorbent: Batch and fixed-bed column adsorption studies

In the present study, the glucose-based carbonaceous adsorbent was prepared from glucose, melamine and urea by using ZnCl2 activation and heated at 550 degrees C under N-2 flow. The sample was treated for the 1st, 2nd and 3rd activation process, and they were characterized by N-2 adsorption and desorption isotherms, elemental analysis and X-ray photoelectron spectroscopy (XPS). The results showed that the content of nitrogen increased and that of oxygen decreased with the increasing of the number of activation process. The adsorbent obtained after the 2nd activation showed the best adsorption properties and was used in batch and fixed-bed column adsorption studies. In batch adsorption experiments, we investigated the factors affecting nitrate adsorption such as initial concentration, solution pH, adsorption isotherms and adsorption kinetics. The isotherm data and kinetic data were fitted well to the Langmuir isotherm model and pseudo-second-order model, respectively, and the maximum adsorption capacity calculated by Langmuir model was 1.58 mmol/g at pH 3. The adsorption performance of the adsorbent in industrial application mode was also investigated by fixed-bed column experiments. The breakthrough time of the packed column was 160 min for the initial nitrate concentration of 200 mg/L at pH 3. The saturated column could be regenerated by 1 mol/L HCl and reused for at least 5 adsorption-desorption cycles. The column showed good adsorption performance in both coexisting ions solution and real contamination water.