Removal heavy metals from water,using magnetite nanosphers

Nazanin Zamani,1,* Negar zamani,2

1. tabriz university of medical science,faculty pharmacy
2. tehran university of medical science

Abstract

Introduction

Exposure to heavy metals is one of the most severe global environment problems.heavy metals are non-biodegradable in nature.(pb2+) is commonly used in households and many industries.lead is commonly used in battery manufacturing, paints,pulps and paper industries. wastewater discharge from battery and paint manufacturing industries are the major anthropogenic lead sources. thus industrial wastewater is considered to be a potential source of lead pollution.excess lead consumption causes anemia,irritability,dizziness and renal sickness. usepa has set the maximum permissible limit of lead in drinking water at 0.015 mg/l. who and the bis have set the maximum permissible limit of pb2+ in drinking water at 0.01 mg/l. chemical precipitation,ion exchange,adsorption, ultrafiltration,membrane separation have been used for metal removal.adsorption is often superior since it is effective,easy handling,flexible and selective.many adsorbents have been used for cr6+ and pb2+ removal, but keen interest exists in improve and advanced low cost adsorbents with high surface areas and sorption capacities. nanosorbents are sought because small particle sizes and high surface areas enhance chemical reactivity and adsorbate interactions and these remove contaminants over a wide concentration range rapidly. we considered nano sized fe304 particles to remove heavy metals due to their magnetic properties, high surface area,chemical stability,easy synthesis and low toxicity.

Methods

Several scientists studies were reviwed in thisretrospective article and some efficinet methods were used for reaching their goal and some of them are written here. first group is yana bagbi and etal that(fe304)nanoparticles were synthesized using a co-precipitation method reported elsewhere. briefly,16.2g fec13 and 6.3g fec12 were dissolved in distilled water and stirred. fe3+-fe2+ solution ph was adjusted to 8.0 using aqueous naoh.after magnetite slurry formation,color turned into black.then ultrasonicated. the liquid phase was separated by centrifugation.the leftover residue was washed to remove any excess alkalinity.then dried. the band gap energy of magnetite nps was determined. ferric chloride hexahydrate, sodium acetate and polyvinylpyrrolidone were added to ethylene glycol.this mixture was covered and stirred on a magnetic stirrer.the color and solution changes from yellowish-brown to dark-brown.the solution was transferred to teflon-lined stainless-steel autoclave and heated in the furnace.the solution was cooled and the black precipitate was separated from the solution by applying external magnetic field,washed with ethanol and vacuum dried. chromium and lead adsorption isotherms were obtained in the 10-100 mg/l concentration range.a known quantity of magnetite nanospheres was added to working solution and shaken at specific temperature for specified time.following magnetic separation,the filtrate was analyzed on a flame atomic absorptionspectrometer.chromium and lead adsorbed was determined.the ground water contains a complex system of ions,which may compete with cr6+/pb2+ during adsorption.to check the interference of other ions on magnetite nanosphere removal efficiency,a groundwater sample was collected from the sahibabad, district ghaziabad,uttar pradesh,india.cr6+ and pb2+ adsorption studies were conducted using spiked samples.a known weight of nanospheres was added to the spiked samples,followed by agitation.magnetic particles were removed using a simple magnet and solutions were analyzed.initially,metals were adsorbed on nanoparticles from solutions.then nanoparticles were stripped using naoh(for cr)and hn03(for pb) by agitating.the nanoparticles were separated and supernatants metal ion concentration was analyzed.

Results

Lead sorption studies were conducted to investigate the effect of initial phs, contact time,temperature and adsorbent concentrations. ground and surface waters contain a complex mixture of ions.these may innuence the adsorption of cr6+ and pb2+ on magnetite nanospheres. therefore, the efficiency of the magnetite nanospheres for cr6+ and pb2+ removal was investigated. a groundwater sample from sahibabad, uttar pradesh, india was analyzed and then spiked with cr6+ and pb2+, separately.the optimum parameters were selected to remediate cr6+ and pb2+ using magnetite nanospheres. and removal of cr6+(up to 65%) and pb2+(up to 70%) was achieved.this can be increased to 100% by increasing the dose of nanospheres.thus, these nanospheres work well to remove cr6+ and pb2+ in presence of other ions.

Conclusion

Finally,our previous studies showed cr(vl) was partially reduced to trivalent chromium cr(iii). further studies are required to address whether those iron oxides can remove pb,cr using either the reduction or adsorption process. moreover,despite that one of the most widely used methods is coprecipitation,magnetite nanoparticles synthesized using different methods or synthesis conditions may display different abilities due to their different sizes and structures.

Keywords

Magnetite nanospheres,solvothermal method,mesoporous, sorption,lead and chromium removal.