Sung H. Han

One-pot synthesis of PVA-capped silver nanoparticles their characterization and biomedical application

The rapid one-pot synthesis of silver nanoparticles (SNPs) at room temperature by using hydrazine hydrate as reducing agent and polyvinyl alcohol as stabilizing agent is reported. The SNPs were characterized with UV-visible (UV-Vis) spectroscopy, x-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM) and transmission electron microscopy (TEM). The synthesized silver nanoparticle shows surface plasmon resonance at 410?nm. The XRD reveals face-centered cubic (FCC) structure of SNPs. FE-SEM, AFM and TEM show that nanoparticles have spherical morphology with diameters in the range of 10?60?nm. The antimicrobial activity of synthesized hybrid material against strains of four different bacteria (Bacillus cereus, Escherichia coli, Staphylococus aureus, Proteus vulgaris), that are commonly found in hospitals has been studied. The results indicate that such particles have potential applications in biotechnology and biomedical science.

Synthesis and enhancement of photocatalytic activities of ZnO by silver nanoparticles

Herein, we reports synthesis, characterization and photocatalytic degradation of Rhodamine B under natural sunlight using zinc oxide and Ag-ZnO composite. Zinc oxide nanoparticles were prepared by simple wet chemical method using ethanol-water mixture. Ag-ZnO composite was prepared in two steps by dispersing synthesized ZnO in silver nitrate solution and subsequently reducing it with Ocimum tenuiflorum leaves extract as bioreducing agent. The synthesized bare zinc oxide and Ag-ZnO composite was characterized by various techniques like XRD, DRS, FE-SEM, TEM, SAED, PSD, Zeta potentials, etc. Zinc oxide being wide band gap material can absorbs UV light from solar spectrum which is only 5% so is not efficient material for dye degradation under sunlight. The absorption of visible light was increased by preparing the Ag-ZnO composite. The enhancement in photocatalytic activities of Ag-ZnO composite was observed than bare ZnO. This enhancement is due to shift of absorption edge of ZnO in visible region and decrease in band gap.

Effect of Sintering Temperatures on the Synthesis of SnO Nanospheres

In this communication we report the rapid nanostructure of SnO2 with a spherical morphology which has been prepared in large scale via sol-gel method. The products were characterized with scanning electron microscopy, X-ray powder diffraction, transmission electron microscopy, FTIR, and photoluminescence spectroscopy. The strong photoluminescence of the nanosphere in visible region suggested possible application in nanoscaled optoelectronic devices. A possible growth mechanism for the SnO2 nanosphere in terms of solvation, hydrolysis, and polymerization was proposed.

Selective determination of selenium(IV) from environmental samples by UV-visible spectrophotometry using O-methoxyphenyl thiourea as a chelating ligand

A selective extraction–spectrophotometric method has been developed for determination of selenium(IV) using O-methoxyphenyl thiourea (OMePT) as a chelating agent. The basis of the proposed method is the spectrophotometric determination of selenium(IV)–OMePT complex obtained after extraction of selenium(IV) from 3.5 M hydrochloric acid media using OMePT in chloroform solvent. The complex shows maximum absorbance at 350 nm against the reagent blank. The Beer’s law was obeyed over the concentration range 5–60 µg mL−1 of selenium(IV). The optimum concentration range was 20–50 µg mL−1 as evaluated from Ringbom’s plot. The molar absorptivity and Sandell’s sensitivity of the selenium(IV)–OMePT complex in chloroform were 3.312 × 102 L mol−1cm−1 and 0.2384 µg cm−2, respectively. The composition of selenium(IV)–OMePT complex was 1:2 established from slope ratio method, mole ratio method and Job’s continuous variation method. The complex was stable for more than 72 h. The interfering effect of various foreign ions was studied and suitable masking agents were used wherever necessary to enhance the selectivity of the developed method. The proposed method was successfully applied for the determination of selenium(IV) from real samples, viz. pharmaceutical formulations, shampoo, vegetable sample, synthetic mixtures and environmental samples. Repetition of the method was checked by finding the relative standard deviation (RSD) for 10 determinations which was 0.35%.

Development of a reliable analytical method for extraction spectrophotometric determination of ruthenium(III) from catalyst and fissium alloy using o-methylphenyl thiourea as a chromogenic chelating ligand

A simple and selective method is developed for the extraction spectrophotometric determination of ruthenium(III) using o-methylphenyl thiourea (OMPT) as a chromogenic chelating ligand. The basis of the proposed method is ruthenium(III)-OMPT complex formation in aqueous hydrochloric acid media (3.0molL(-1)) after 5.0min heating on a boiling water bath and the complex formed is extracted into chloroform. The absorbance of green colored ruthenium(III)-OMPT complex is measured at 590nm against the reagent blank. Beers law was obeyed up to 42.5μgmL(-1) of ruthenium(III) and the optimum concentration range is 7.56-39.81μgmL(-1) of ruthenium(III) as evaluated by Ringboms plot. Molar absorptivity and Sandells sensitivity of ruthenium(III)-OMPT complex in chloroform are 2.34×10(3)Lmol(-1) cm(-1) and 0.043μgcm(-2) respectively. The composition of ruthenium(III):OMPT complex (1:2) was established from slope ratio method, mole ratio method and Jobs continuous variation method. Complex was stable for more than 48h. The interfering effect of various foreign ions was studied and suitable masking agents are used wherever necessary to enhance the selectivity of the method. Proposed method is successfully applied for determination of ruthenium(III) from binary and ternary synthetic mixtures, synthetic mixtures corresponding to fissium alloy and ruthenium catalyst. Repetition of the method was checked by finding relative standard deviation (R.S.D) for 10 determinations which was 0.23%. A scheme for sequential separation of palladium(II), ruthenium(III), rhodium(III) and platinum(IV) has been developed.