The mixture was reduced by 8(M) ammonia solution. â A black slurry was produced. â Nanoparticles were separated using magnetic decantation and washed ...
Effective removal of heavy metals and dyes from drinking water utilizing bio-compatible magnetic nanoparticle Dwiptirtha Chattopadhyay, Keka Sarkar*
Department of Microbiology, University of Kalyani, Kalyani – 741235, West Bengal, India.
: Introduction :
: Aim of the work : Removal of heavy metal (Cr) and dye (MG) from drinking water were investigated in a cost-effective, rapid, environment friendly way utilizing magnetic nanoparticles.
Objectives 1. Synthesis and characterization of iron nanoparticle by a novel technique. 2. Reactivity of as synthesized particle on microbial growth for bio-compatible properties. 3. Potentiality of the surface modified particle towards removal of heavy metal (e.g – Cr) and dye (e.g – Malachite Green (MG)) from water.
1. Synthesis of iron nanoparticle by a novel technique Same volume of FeSO4 and KNO3 were taken in a tube. The mixture was reduced by 8(M) ammonia solution. A black slurry was produced. Nanoparticles were separated using magnetic decantation and washed with methanol. The nanoparticles were kept in methanol and surface modified accordingly for various applications.
Characterization of the synthesized iron nanoparticle : As synthesized iron nanoparticles were characterized using TEM, SEM and DLS. From TEM image the size of the iron particle was found to be 6 to 7 nm. SEM image implied amorphous nature of the nanoparticle which is again supported by the SAED pattern analysis. From DLS the Zeta potential (ζ) of the particle was found to be –26.9 mV.
SAED pattern of iron nanoparticle
TEM image of iron nanoparticle
SEM image of iron nanoparticle
Zeta potential data of iron nanoparticle
Surface modification of iron nanoparticle – Synthesis of Glutathione coated iron nanoparticle : It was prepared by slowly adding 1 g of iron nanoparticle in 30 mM glutathione solution (pH – 9) under steering condition (2000 rpm).
Synthesis of Sodium Dodecyl Sulfate (SDS) coated iron nanoparticle : For SDS coating 5% (w/v) SDS solution was prepared in water and to it 1 g of iron nanoparticle was added slowly under steering condition (515 rpm).
UV-Vis spectrophotometric data demonstrating the surface fictionalization of iron nanoparticle by SDS and GSH with control :
2. Bacterial Growth experiment The comparative study on growth of bacteria under normal condition and under the influence of magnetic nanoparticle was carried out. Various concentration of nanoparticles (i.e 100 μg/mL, 200 μg/mL ) were added into 50 mL LB medium containing E. coli DH5α (a) and B. subtilis (b) separately, along with control to track the normal microbial growth . Optical density measurement at 600 nm indicated the bacterial growth interacting with nanoparticle and the viability was determined from a plot of the log of the optical density versus time.
3. Potentiality of the surface modified particle towards removal of A) Heavy metal (Cr) and B) Dye (Malachite Green (MG)) from water
Chromium
Chromium ranks 21st among the elements in crustal abundance.
The hexavalent species i.e. Cr(VI) is most toxic because of its high mobility.
Occupational exposure to Cr(VI) compounds leads to a variety of clinical problems like – perforation of the nasal septum, asthma, bronchitis, pneumonitis, inammation of the larynx and liver and increased incidence of bronchogenic carcinoma.
Skin contact of Cr(VI) compounds can induce skin allergies, dermatitis, dermal necrosis and dermal corrosion.
The toxicological impact of Cr(VI) originates from the action of this form itself as an oxidizing agent, as well as from the formation of free radicals during the reduction of Cr(VI) to Cr(III) occurring inside the cell.
Recommended maximum allowable concentration in drinking water for chromium (VI) is 0.05 mg per liter .(WHO)
A) Uptake studies of Chromium (VI) in batch process
Cr(VI) uptake studies have been performed using glutathionated iron nanoparticles. Adsorption studies were performed by adding different concentration (0.1 – 1.0 µg/mL) of potassium di-chromate to 100µg/mL, 200µg/mL and 400µg/mL of GSHloaded iron nanoparticles separately (at pH 7). After desired incubation (24 h at 37 ± 2 °C) Cr(VI) loaded nanoparticles were separated with magnetic decantation and the supernatant has been analyzed for Cr(VI) concentration using Cr(VI) specific colorimetric reagent Sdiphenylcarbazide (DPCZ).
Effect of pH on Cr(VI) adsorption Chromium(VI) absorption by the GSH-iron nanoparticle was evaluated at different pH (3, 11).
Malachite Green (MG)
Malachite green, chemically is a triarylmethane dye.
Used as a dyestuff and has emerged as a controversial agent in
aquaculture. It is highly effective against important protozoal, fungal and helminthic infections.
It is also used as a food coloring agent, food additive, a medical disinfectant and ant as well as a dye in silk, wool, jute, leather, cotton, paper and acrylic industries.
Its effects on the immune system, reproductive system and genotoxic, carcinogenic properties have been found recently.
Use of this dye has been banned in several countries and not approved by US Food and Drug Administration.
B) Absorption studies of Dye (Malachite Green – MG) using SDS coated iron nanoparticle MG uptake studies were performed in a batch process. Adsorption studies were performed by adding water sample containing MG to SDS-loaded iron nanoparticles . At pH 3.0 the adsorption was highest . After incubation (24 hr) the MG loaded nanoparticles were separated with magnetic decantation. Concentration of MG in the supernatant was monitored spectrophotometrically by measuring the absorbance of the solution at 627 nm.
: Conclusion : Our preliminary study of heavy metal removal (Cr(VI)) and dye (MG) removal using surface functionalized iron nanoparticle showed excellent efficiency. This novel and convenient procedure is safe, rapid and inexpensive for adsorption and removal of toxic compounds from water compared to the other troublesome methods. Further study to optimize the adsorption efficiency should be performed that would develop cost effective, reusable platform to mitigate the pollution.
: Acknowledgement :
This research work has been carried out with the financial support of: University Grant Commission, Govt. of India (Major Research Project-41-1178/2012SR) & University of Kalyani, Kalyani , Nadia, West Bengal.
: References : 1) A. Afkhami, R. Moosavi, T. Madrakian; Talanta, 2010 ,785: 82. 2) W. Zhang;Journal of Nanoparticle Research, 2003, 323: 5. 3) Chatterjee S, Bandyopadhyay A , Sarkar K ; 2011 , Journal of Nanobiotechnology. 9:34. 4) Urone. PF ; 1955, Anal. Chem. 27: 1354–1355. 5) Culp SJ, Beland FA ; 1996. J. Am. Coll. Toxicol. 15: 219-238. 6) Hiraide M, Sorouradin MH, Kawaguchi H ; Anal. Sci, 1994, 10: 125-128.
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