Search Results

You are looking at 1 - 3 of 3 items for

  • Author: Zahoor H. Farooqi x
Clear All Modify Search
Open access

Zahoor H. Farooqi, Zonarah Butt, Robina Begum, Shanza Rhauf Khan, Ahsan Sharif and Ejaz Ahmed

Abstract

Poly(N-isopropylacrylamide-co-methacrylic acid) microgels [p(NIPAM-co-MAAc)] were synthesized by precipitation polymerization of N-isopropylacrylamide and methacrylic acid in aqueous medium. These microgels were characterized by dynamic light scattering and Fourier transform infrared spectroscopy. These microgels were used as micro-reactors for in situ synthesis of copper nanoparticles using sodium borohydride (NaBH4) as reducing agent. The hybrid microgels were used as catalysts for the reduction of nitrobenzene in aqueous media. The reaction was performed with different concentrations of cat­alyst and reducing agent. A linear relationship was found between apparent rate constant (kapp) and amount of catalyst. When the amount of catalyst was increased from 0.13 to 0.76 mg/mL then kapp was increased from 0.03 to 0.14 min-1. Activation parameters were also determined by performing reaction at two different temperatures. The catalytic process has been discussed in terms of energy of activation, enthalpy of activation and entropy of activation. The synthesized particles were found to be stable even after 14 weeks and showed catalytic activity for the reduction of nitrobenzene.

Open access

Zahoor H. Farooqi, Tanzila Sakhawat, Shanza Rauf Khan, Farah Kanwal, Muhammad Usman and Robina Begum

Abstract

Poly(N-isopropylacrylamide-co-acrylic acid) [P(NIPAM-co-AAc)] microgels were synthesized by precipitation polymerization. Copper nanoparticles were successfully fabricated inside the microgels by in-situ reduction of copper ions in an aqueous medium. The microgels were characterized by Fourier Transform Infrared Spectroscopy (FT-IR) and Dynamic Light Scattering (DLS). Hydrodynamic radius of P(NIPAM-co-AAc) microgel particles increased with an increase in pH in aqueous medium at 25 °C. Copper-poly(N-isopropylacrylamide-co-acrylic acid) [Cu-P(NIPAM-co-AAc)] hybrid microgels were used as a catalyst for the reduction of 4-nitrophenol (4-NP). Effect of temperature, concentration of sodium borohydride (NaBH4) and catalyst dosage on the value of apparent rate constant (kapp) for catalytic reduction of 4-NP in the presence of Cu-P(NIPAM-co-AAc) hybrid microgels were investigated by UV-Vis spectrophotometry. It was found that the value of kapp for catalytic reduction of 4-NP in the presence of Cu-P(NIPAM-co-AAc) hybrid microgel catalyst increased with an increase in catalyst dosage, temperature and concentration of NaBH4 in aqueous medium. The results were discussed in terms of diffusion of reactants towards catalyst surface and swelling-deswelling of hybrid microgels.

Open access

Maria Arshad, Abbas Khan, Zahoor H. Farooqi, Muhammad Usman, M. Abdul Waseem, Sayyar Ali Shah and Momin Khan

Abstract

Due to their potential application in various fields of science and technology, the eco-friendly bio-synthesis of silver (Ag) nanoparticles (NPs) is a growing area for researchers. In this study, we report the green synthesis of Ag nanoparticles and their characterization by using various techniques. For the preparation of Ag particles, aqueous plant extract of ailanthus altissima was used as a reducing medium for Ag+ ions of silver nitrate to Ag0. UV-Vis spectrophotometry was used to trace the formation of Ag particles by noting their surface plasmon resonance peaks (400 nm to 440 nm). Fourier transform infrared spectroscopy (FT-IR) was employed to reveal the chemical composition of Ag nanoparticles which were capped by plant extract. Scanning electron microscopy (SEM) was used to get the lattice image, morphology and average size of Ag particles. The average size distribution of Ag NPs dispersed in aqueous media was also measured using dynamic light scattering (DLS). It was found that DLS results are in good agreement with those obtained from SEM. The synthesized particles were then subjected to the antibacterial and antifungal activities by studying them against various species, such as bacillus cereus, staphylococcus aureus, pseudomonas aeruginosa, E. coli and A. parasiticus, A. niger and A. flavus fungi. It was noted from the growth curves of both bacteria and fungi that in the presence of silver nanoparticles they show more in-zone growth as compared to the plant extract.