Dr. PARESHKUMAR YOGESHBHAI PAREKH
@vnsgu.ac.in
Assiatant Professor, Veer Narmad South Gujarat University
Veer Narmad south Gujarat University
RESEARCH, TEACHING, or OTHER INTERESTS
Analytical Chemistry, Polymers and Plastics, Materials Chemistry, Physical and Theoretical Chemistry
Scopus Publications
Scholar Citations
Scholar h-index
Scholar i10-index
Scopus Publications
Tanzila Pathan, Mayursing Girase, Debes Ray, Shailesh Padsala, Paresh Parekh, Mehul Khimani, Sabir Pathan, Ketan Kuperkar, Vinod K. Aswal, and Vijay I. Patel
Elsevier BV
Ankur Patel, Debes Ray, Paresh Parekh, Ketan Kuperkar, Bhavesh Bharatiya, Vinod K. Aswal, Pratap Bahadur, and Vijay I. Patel
Elsevier BV
Vijay Patel, Paresh Parekh, Mehul Khimani, Shin-ichi Yusa, and Pratap Bahadur
Elsevier BV
Paresh Y. Parekh, Vijay I. Patel, Mehul R. Khimani, and Pratap Bahadur
Elsevier BV
Ankur Patel, Debes Ray, Paresh Parekh, Vinod K. Aswal, Pratap Bahadur, and Vijay I. Patel
Elsevier BV
Ankur Patel, Debes Ray, Mehul Khimani, Jigisha K. Parikh, Paresh Parekh, Vijay I. Patel, Vinod K. Aswal, and Pratap Bahadur
Elsevier BV
Chitralekha Chakrabarti, Mehul Khimani, Vijay Patel, Paresh Parekh, Sadafara Pillai, Jitendra Mata, Rohit L. Vekariya, Poonam Bhadja, and Mohd. Muddassir
Elsevier BV
Paresh Parekh, Sayaka Ohno, Shin‐ichi Yusa, Chao Lv, Binyang Du, Debes Ray, Vinod Kumar Aswal, and Pratap Bahadur
Wiley
AbstractPoly(ethylene oxide)–poly(propylene oxide)–poly(ethylene oxide) (PEO–PPO–PEO) triblock copolymer (Pluronic F127) was modified by introducing poly(N‐isopropylacrylamide) (PNIPAM) at both the PEO ends, and the pentablock copolymer (PNIPAM41–F127–PNIPAM41, PN41) so prepared was characterized using gel permeation chromatography and 1H NMR spectroscopy. The degree of polymerization of NIPAM blocks at the two ends was 41. The solution behaviour and microstructure of PN41 aggregates in water were examined using UV–visible spectroscopy, micro‐differential scanning calorimetry and small‐angle neutron scattering (SANS) and compared with F127. Two lower critical solution temperatures (LCSTs) were observed for the pentablock copolymer, corresponding to PPO and PNIPAM blocks, respectively. The adsorption of PN41 on thiol‐grafted hydrophobic gold surfaces at various temperatures was investigated using a quartz crystal microbalance. It was found that the adsorption behaviour and mechanism of PN41 were mainly determined by the interactions of the pentablock copolymers with different chain conformations in dilute aqueous solutions at various temperatures. SANS measurements were used to determine the temperature‐dependent structural evolution of polymer micelles in aqueous solution. A NOESY study revealed that above the LSCT of PNIPAM, the interaction of PPO and PNIPAM protons increases and the distance between PPO and PNIPAM decreases. © 2019 Society of Chemical Industry
Mehul Khimani, Hiren Patel, Vijay Patel, Paresh Parekh, and Rohit L. Vekariya
Springer Science and Business Media LLC
Amit G. Shirke, Paresh Parekh, Bharatkumar Dholakiya, and Ketan Kuperkar
Wiley
AbstractUse of polyester‐type polyurethane foam (PUF) is an effective adsorbent for the removal of hazardous dye: crystal violet (CV) from an aqueous solution. In this adsorption study, the formation of hydrophobic ion pair (opposite charge attraction) between the charged species, i.e., cationic (basic) dye CV and anionic surfactant sodium dodecylsulfate (SDS) sorbed onto PUF. Chemical calculations were performed using quantum simulation to understand ion‐pair formation for CV–SDS at the semiempirical PM6 level. Adsorption studies were performed using 200 mg cylindrical PUF with an overhead stirrer in solutions containing varying compositions of the dye–surfactant mixture. The equilibrium thermodynamics and kinetics of the adsorption process were studies by measuring CV dye removal as a function of time and temperature. Results show that the formation of the dye–surfactant ion pair is necessary for effective adsorption onto PUF. Various adsorption isotherms, viz., Langmuir, Freundlich, Temkin, Dubinin–Radushkevich (DRK), Harkin‐Jura, and several kinetic models, viz., pseudo‐first order, pseudo‐second order, Elovich, and Intraparticle diffusion were used to fit the spectrophotometric result. The equilibrium adsorption data fit to the Langmuir isotherm gives the maximum adsorption of PUF as 33.39 mg g−1 from 200 mL 5.0 × 10−5 mol L−1 CV solution at 298.15 K. The kinetics study showed that the overall adsorption process follows pseudo‐second‐order kinetics. The Morris–Weber model suggests that an intraparticle diffusion process is active in controlling the adsorption rate. The Freundlich, Temkin, DRK adsorption isotherms showed that solute dye transfers from solution to the PUF adsorbent surface through physical adsorption. The Langmuir and Harkin‐Jura adsorption isotherms suggest that the adsorbent surface is homogeneous in nature. The thermodynamic data showed that the adsorption process is spontaneous and endothermic with a positive enthalpy change and a negative change in Gibb's energy.
U. Patel, P. Parekh, N.V. Sastry, V.K. Aswal, and P. Bahadur
Elsevier BV
Urja Patel, Paresh Parekh, Debes Ray, Vinod Kumar Aswal, Pratap Bahadur, and Rajib Ganguly
Wiley
P. Parekh, S. Ohno, S. Yusa, Emílio V. Lage, Matilde Casas, I. Sández-Macho, V. K. Aswal, and P. Bahadur
American Chemical Society (ACS)
The triblock Pluronic F127 was modified by introducing poly(N-isopropylacrylamide) (PNIPAM) at both the poly(ethylene oxide) ends, and the pentablock copolymer so-prepared was characterized by gel permeation chromatography and (1)H NMR. The degree of polymerization of NIPAM blocks at the two ends was 7. The solution behavior and microstructure of copolymer aggregates in water and aqueous salt solution were examined and compared with F127 by UV-visible absorption spectroscopy, microdifferential scanning calorimetry, dynamic light scattering (DLS), and small-angle neutron scattering (SANS). The behavior of the pentablock copolymer at the air/water interface was determined by Langmuir film balance. Two lower critical solution temperatures were observed for pentablock copolymer, corresponding to poly(propylene oxide) and PNIPAM blocks, respectively. DLS studies show that micelle size increased with increase in temperature and in the presence of salt. SANS measurements provided temperature-dependent structural evolution of copolymer micelles in water and salt solution. The copolymer displays an isotherm with four classical regions (pancake, mushroom, brush, and condensed state). The study has potential applications in controlled drug delivery due to the tunable phase behavior and biocompatibility of the copolymer.
P. Parekh, J. Dey, S. Kumar, S. Nath, R. Ganguly, V.K. Aswal, and P. Bahadur
Elsevier BV
Mehul Khimani, Paresh Parekh, Vinod K. Aswal, and Pratap Bahadur
Springer Science and Business Media LLC
A. Parmar, P. Parekh, and P. Bahadur
Springer Science and Business Media LLC
R. Ganguly, K. Kuperkar, P. Parekh, V.K. Aswal, and P. Bahadur
Elsevier BV
P. Parekh, R. Ganguly, V. K. Aswal, and P. Bahadur
Royal Society of Chemistry (RSC)
The influence of salicylic acid (SA) on the aggregation characteristics of Pluronic® P85 has been studied in the aqueous medium by dynamic light scattering (DLS), small angle neutron scattering (SANS), steady-state fluorescence and rheological measurements. DLS studies suggest that SA, which is used in the treatment of various skin diseases, induces a room temperature growth of the P85 micelles. Steady-state fluorescence studies and cloud point measurements attribute this to the ability of SA to stay in micellar corona and consequently dehydrate the copolymer micelles by displacing water from the corona region. A large increase in the viscosity of the P85 solutions accompanying the observed micellar growth, and SANS and rheological studies reveal that the P85 micelles undergo a sphere-to-rod shape transition in the presence of SA. Pluronics® being biomedically important surfactants, the observed effects suggest that P85 could be considered as a suitable agent as a carrier of SA, as well as a viscosity modifier of the formulations of SA. The studies also show that the effectiveness of SA in causing the observed micellar dehydration increases with a decrease in pH, which suggests that the observed effects of SA on the P85 micelles arise due to the presence of the unionized form of the SA in the micellar corona region. Rheological studies show that unlike other Pluronic® worm like micellar systems, the viscoelastic behavior of the present system shows close conformity with the Maxwell law. Such difference in the behavior has been attributed to faster restructuring and breaking processes of the P85 micelles due to the high hydrophilic PEO group content (50%) of P85 molecules.
P. Parekh, K. Singh, D.G. Marangoni, V.K. Aswal, and P. Bahadur
Elsevier BV
Paresh Parekh, Kulbir Singh, D. Gerrard Marangoni, Vinod K. Aswal, and Pratap Bahadur
Wiley
P. Parekh, K. Singh, D.G. Marangoni, and P. Bahadur
Elsevier BV
Paresh Parekh, Arpan Parmar, Suresh Chavda, and Pratap Bahadur
Informa UK Limited
In present study, we have investigated the effect of an anionic surfactant sodium dodecyl sulfate (SDS) and clay on calcium alginate beads was studied to remove methylene blue (MB) and to improve the adsorption capacity. The effects of various experimental parameters, such as shaking rate, initial dye concentration, temperature, and pH on the adsorption rate, have been studied. Equilibrium studies showed that the sorption of the dye was enhanced in presence of SDS. Scanning electron microscope (SEM) analysis showed that SDS entrapped beads have more pores and cavities which could be responsible for improved adsorption of MB. The kinetics of cationic dye adsorption nicely followed pseudo-second-order process. The evaluated thermodynamic parameters (ΔG o, ΔH o, ΔS o) suggest endothermic adsorption of MB. The results revealed that the surfactant entrapped alginate could be considered as potential adsorbents for MB removal from aqueous solutions.
P. Parekh, D. Varade, J. Parikh, and P. Bahadur
Elsevier BV