Groundwater nitrate contamination: Assessment and treatment usingMoringa oleiferaLam. seed extract and activated carbon filtration

Adsorption study of heavy metals in aqueous solutions aiming at the treatment of contaminated groundwater

This study evaluates the application of the vegetal activated carbon (AC), vegetable AC impregnated with Ag and Cu (0.08% m/m) and cationic Supergel^TM SGC650H resin for adsorption of Fe³⁺ and Pb²⁺ ions in closed and batch system. The best adsorption capacities were obtained by using the cationic resin SGC650H, pH 3, temperature of 30 °C and stirring speed of 100 rpm. Thus, the kinetic and equilibrium experiments, in mono- and bicomponent, were performed using SGC650H resin, wherein the kinetic models of pseudo-first and pseudo-second order presented a good fit to the kinetic data, for mono- and bicomponent, respectively. The Langmuir isotherm adequately represented the monocomponent equilibrium data, showing maximum adsorption capacities values of 7.18 and 4.00 meq g^-1 for Fe³⁺ and Pb²⁺, respectively. An inhibitory effect between the metal species was verified by fitting the modified extended Langmuir isotherm model to the binary equilibrium data, which allowed to predict changes in the surface affinity to the adsorbent by the metal ions. Based on the observed results, the use of SGC650H resin presents great potential for water treatment systems contaminated with heavy metals.

Water decontamination containing nitrate using biosorption with Moringa oleifera in dynamic mode

This study was conducted to assess the feasibility of using Moringa oleifera Lam. (MO) seeds in the biosorption of nitrate present in aqueous solutions by means of batch and fixed-bed column biosorption processes. The batch assays showed that nitrate biosorption is enhanced under experimental conditions of pH 3 and a biosorbent mass of 0.05 g. For the experiments in dynamic mode, the results obtained from the statistical parameters showed that lesser pH, lesser feed flow rate, and higher initial concentration will result in an increase of the maximum capacity of the bed. These conditions were confirmed by experimental analysis. The best experimental conditions, according to the values for percentage removal (91.09%) and maximum capacity (7.69 mg g^-1) of the bed, were those used in assay 1, which utilized pH 3, feed flow rate of 1 mL min^-1, and initial nitrate concentration of 100 mg L^-1.