Synthesis of superparamagnetic fe3o4@edta-ldh nanoparticles and its application in removing lead and cadmium ions contaminants from aqueous solutions

Samira Baniali,1 Ensieh ghasemi,2,* Akbar heydari,3 Zahra mousavi,4

1. department of toxicology ,Faculty of Pharmaceutical Sciences, Tehran Medical Sciences, Islamic Azad University
2. department of toxicology ,Faculty of Pharmaceutical Sciences, Tehran Medical Sciences, Islamic Azad University

Abstract


Introduction

Healthy drinking water has always been one of the most vital human needs. today, with increasing industrial activities and the entry of pollutants, including heavy metals to water resources, safe water supply has become a serious challenge. therefore, finding a method to remove these pollutants is important. the present study was aimed to produce fe3o4@edta-ldh nanoparticles and investigate its efficacy in absorbing lead and cadmium ions from laboratory and environmental samples.

Methods

materials: all chemicals used here were of reagent grade and used without further purification. ultrapure water was collected from a milli-q water purification system. analytical-grade fecl2•4h2o, fecl3•6h2o, ammonia (37%), al(no3)3, mg(no3)2 and ethylene diamine tetra acetic acid (edta) were obtained from sigmaaldrich. the heavy metals stock solutions (1000 mg.l−1) were prepared by dissolving an appropriate amount of their nitrate salts (merck, darmstadt, germany) in ultrapure water. the working solutions were prepared daily by appropriate dilution of the stock solutions in ultrapurewater. all glassware was rinsed with deionized water and dried in a dust-free environment before use. methods: adsorption of the heavy metals ions from aqueous solutions were investigated in batch experiments. fresh dilutions were used in each experiment. the adsorptions were carried out in a 50 ml beaker containing 5 mg.l−1 of each analyte in 10 ml deionized water. after addition of 50 mg of fe3o4@edta-ldh nanoparticles, the solution was gently stirred for 20 min using a mechanical stirrer at a constant rate of 800 rpm to facilitate the adsorption of the analytes onto the nanoparticles. after a period of time, magnetic nanoadsorbents were separated from the solution by magnetic separation. the initial and final concentration of pb(ii) and cd(ii) were determined using an aas. the removal efficiency of target ions adsorbed onto fe3o4@edta-ldh nanoparticles and the adsorption capacity were calculated by the following equations: [removal efficiency (%) = (ci – cf)/ ci *100] where ci and cf (mg.l−1) are the initial and final concentrations of the target heavy metals.

Results

According to the results of fourier transform infrared spectroscopy (ft-ir), x-ray diffraction (xrd) and scanning electron microscope (sem) the successful synthesis of nanoparticles was ensured. in order to achieve the highest efficiency, the laboratory conditions were optimized for ph = 7, time = 20 min, and fe3o4@edta-ldh = 0.05 g using the box-behnken design (bbc). the amount of cation adsorption by nanoparticles was measured using a atomic absorption spectroscopy (aas). the results of the experiments showed that in optimal conditions, fe3o4@edta-ldh nanoparticles has an efficiency of 90 to 100 percent for the removal of pb2+ and cd2+ ions from laboratory. the results of the environmental samples showed an average of 97% for the absorption of pb2+ and cd2+ by nanoadsorbent. reabsorption tests were also studied and showed a high efficiency of 98% using hcl solvent (0.5 mol / l).

Conclusion

In this study, a simple, novel and high efficient treatment technique based on the super paramagnetic fe3o4@edta-ldh nanoparticles was utilized for simultaneously adsorption and removal of pb(ii) and cd(ii) from different environmental water samples. the experimental parameters of removal process such as amount of nanoadsorbent, ph and adsorption time were optimized using a box–behnken design. under the optimum condition, the removal efficiencies in the range of 96–104% were obtained. the average removal efficiency for simultaneously removal of target ions was ≥99% at optimum condition. desorption and regeneration experiments was studied with eluent of hcl in different concentration and satisfactory results were obtained. also, the results of interference effect of coexistence cations show that the adsorption efficiencies of the studied heavy metals ions are almost unaffected up to the examined concentrations. the developed method proved to be a simple, fast, effective, sensitive with high removal efficiencies, with good reproducibility and repeatability. furthermore, after the adsorption process, the easy separation is provided only by applying an external magnetic field. finally, it can be concluded that the proposed method is an effective and less time consuming technique for simultaneously removal of target heavy metal ions in different environmental water samples.

Keywords

Fe3o4@edta-ldh, magnetic nanoparticles, heavy metals, magnetic layered double hydroxide