Removal of nitrate from aqueous solution using modified granular activated carbon

Abstract

In this study, a commercial granular activated carbon was modified with sodium hydroxide followed by a cationic surfactant to increase its efficiency for nitrate removal from water. Physicochemical properties of untreated activated carbon and treated activated carbons were characterized in the terms of FTIR spectroscopy, N 2 adsorption-desorption, and SEM analyses. The surface properties of ACs were determined by N 2-adsorption isotherm data and modeled with several mathematical models. The results showed that the combination of two treatments could improve the nitrate removal efficiency, which is mainly attributed to the modification by cationic surfactant, while the porous volume and specific surface area did not seem to play an important role in the nitrate uptake. In batch experiments, the influence of several operating parameters on the nitrate adsorption capacity was investigated including solution pH, adsorbent dosage, contact time, initial nitrate concentration, temperature and competing ions. Small continuous column test was performed to investigate the feasibility of using each adsorbent. Results of this study suggest that using two-step treatment can be a promising method to enhance the efficiency of activated carbon for nitrate removal from water.

Assessment of Surfactant Modified Activated Carbon for Improving Water Quality

“…However, treatment with NaOH or HNO 3 prior to surfactant modification has been shown to minimise the reduction in the BET specific surface surface or micro pore volume and ultimately increase the net surface charge of the modified activated carbons. Mazarji et al [27] recorded that the BET specific surface area and micro pore volume of a virgin activated carbon, 888 m 2 /g and 0.376 cm 3 /g increased to 901 m 2 /g and 0.400 cm 3 /g respectively after NaOH treatment but slightly reduced to 722 m 2 /g and 0.310 cm 3 /g after CTAB modification of the NaOH treated activated carbon. They obtained percentage nitrate removal of NaOH-CTAB modified activated carbon, 80%, >NaOH-pre-treated activated carbon, 16% > virgin activated carbon, 8%.…”

“…However, increase in initial concentration increases the driving force causing more adsorbate to bind onto the adsorbent. Hence, for a fixed mass of adsorbent, increase in initial concentration of adsorbate increases the specific adsorbate uptake until equilibrium is attained [26] [27].…”

“…In addition, reduction of the micro-pore volume above CMC has high tendency of masking the active binding sites originally present on the virgin activated carbon thereby reducing their contribution to physical adsorption, surface complexation and electrostatic interaction to the main ion exchange. Few researchers fixed surfactant concentration below CMC [17] [27] or above CMC [21] during adsorption experiments. Such approach may prevent optimising the capacity of the modified activated carbons.…”

Adsorption of Nitrate onto ZnCl2‐Modified Coconut Granular Activated Carbon: Kinetics, Characteristics, and Adsorption Dynamics

“…Adsorption, in general, is the removal process of soluble substances that are in solution on a suitable interface [1]. Activated carbon has gained wide attention as an efficient adsorbent which can adsorb various pollutants in aquatic phase especially organic pollutants [12]. However, it shows poor adsorption towards anionic pollutants.…”

Activated carbon produced from Glycyrrhiza glabra residue for the adsorption of nitrate and phosphate: batch and fixed-bed column studies

“…Urbanization, industrialization, high usage of agricultural fertilizers, combined with inappropriate treatment of wastewater, have led to contamination of the environment and groundwater resources by toxic pollutants including organic, and inorganic ions like nitrate and phosphate. Nitrogen and phosphorous are used in agriculture due to their high solubility in water and nutritious values for the plants [1][2][3]. However, excessive release of nitrate and phosphate to the environment adversely affects the ecosystem and human health [4,5].…”