Micellar effect upon the rate of alkaline hydrolysis of carboxylic and carbonate esters

AbstractThe alkaline hydrolysis of carboxylate (1-naphthylbutyrate) and carbonate esters (2-(methylsulfonyl)-ethyl-4-nitrophenylcarbonate) in the presence of different surfactants has been studied. The rate of hydrolysis of these esters was determined under pseudo first order condition in which the concentration of NaOH was kept in large excess over the [ester]. The cationic micelles of cetyltrimethylammonium bromide (CTABr) and cetyltrimethylammonium sulfate ((CTA)2SO4) enhanced the rate of hydrolysis of esters to a maximum value and thereafter, the increasing concentration of surfactant decreased the reaction rate. The anionic micelles of sodium dodecyl sulfate (SDS) inhibited the rate of the hydrolysis. The reaction proceeds through the attack of OH− ions on the carbonyl carbon forming tetrahedral intermediate. The tetrahedral intermediate is unstable and collapses immediately to yield respective acid and alcohol. The micelles influence the stability of tetrahedral intermediate, in turn, altering the rate of hydrolysis. The variation in the rate of hydrolysis by micelles was treated by considering the pseudophase ion-exchange model and Menger–Portnoy model. The added salts viz. NaBr, NaCl, and LiCl inhibited the rate of the reaction in the presence of cationic and anionic micelles. The kinetic parameters i.e. km and Ks were determined from the rate–[surfactant] profile

High-efficiency DNA extraction using poly(4,4′-cyclohexylidene bisphenol oxalate)-modified microcrystalline cellulose magnetite composite

In this study, we studied the DNA extraction capability of poly(4,4-cyclohexylidene bisphenol oxalate) following the surface modification and composite formation with that of microcrystalline cellulose (MCC) and magnetic iron oxide nanoparticles (NPs). The physical characterization techniques like scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectroscopy, energy-dispersive X-ray analysis (EDX), and thermogravimetric analysis (TGA) were employed for the poly(bisphenol Z oxalate)-MCC-magnetite composite during different stages of its formation. The results confirmed the successful modification of the polymer surface. On testing in the presence of three types of binding buffers, a high value of 72.4% (out of 10,000 ng/μL) efficiency with a total yield of DNA at ng and absorbance ratio of A260/A280 (1.980) was observed for the 2 M GuHCl/EtOH binding buffer. These results were compared against the other two buffers of phosphate-buffered saline (PBS) and NaCl. The lowest value of DNA extraction efficiency at 8125 ng/μL of 58.845% with absorbance ratios of A260/A280 (1.818) for PBS was also observed. The study has concluded an enhancement in the DNA extraction efficiency when the polymer is in the composite stage along with cellulose and magnetite particles as compared against the bare polymer

Nickel nanoparticles-modified electrode for the electrochemical sensory detection of Penicillin G in bovine milk samples

The monitoring of chemical and antibiotic residues like amoxicillin, penicillin, tetracycline, and vancomycin in the food originating from the animal and plant sources can prevent the humans from getting exposed to the antibiotic-induced allergic reactions and also decreased immunity towards the microbial population. By taking into consideration the necessity of developing effective and sensitive techniques for milk containing Penicillin G antibiotics in an easy and cost-effective mode, the present work deals with the electrochemical sensor made up of nickel nanoparticles (NiNPs). In order to enhance the chemical stability and biocompatibility, the NiNPs were crosslinked with (3 aminopropyl)triethoxysilane (APTES) and the formed composite was thoroughly characterized using the physical characterization techniques. In addition, the qualitative analysis results confirmed the nanocomposite’s synergetic effect towards the oxidation of Penicillin G. Further, the quantitative analysis towards the use of a nanocomposite electrode due to the changes in pH, scan rate, accumulation time and potential, nanoparticle (NP) amount, etc. was optimized. The limit of detection and limit of quantitation of Penicillin G with this composite were detected to be 0.00031 μM and 0.00100 μM, respectively. Overall, from the results, it can be indicated that the fabricated NiNP sensor can find its applications as a potential electrode material for the qualitative and quantitative analysis of Penicillin G in liquid samples

Ply-stacking effects on mechanical properties of Kevlar-29/banana woven mats reinforced epoxy hybrid composites

© The Author(s) 2022. This is an open access article distributed under the Creative Commons Attribution License, to view a copy of the license, https://creativecommons.org/licenses/by-nc/4.0/Development of new hybrid laminated composites of Kevlar-29 (K-29)/banana fiber (Musa acuminata) mats to meet future demand for fiber reinforced polymer (FRP) composites has been investigated. The different ply-stacking sequenced Kevlar (K)/natural (N) banana reinforced epoxy polymeric hybrid composite samples were designated as KN1, KN2, KN3, KN4, KN5 and KN6, in addition to NN7 and KK8 for single or non-hybrid FRP (control) composite samples. The ply-stacking effects on mechanical properties of all the laminated composite were investigated. The maximum tensile, flexural, impact and interlaminar shear strengths (ILSS) were obtained with sample KN4, because of the stacking of its Kevlar and natural banana mats, which was K2/N4/K2 of 8 layers and different from other stacking sequences. The percentage improvements on tensile strength of sample KN4 when compared with other hybrid composite samples KN1, KN2, KN3, KN5 and KN6 were 6.3, 4.4, 3.6, 13.1 and 11.3%, respectively. While, same optimum sample KN4 recorded highest flexural strength among hybrid samples with percentage improvements of 122.19, 70.97, 31.03 and 83.68% when compared with other hybrid samples KN2, KN3, KN5 and KN6, respectively. Similar trend of results was obtained for their tensile and flexural moduli. But, both hybrid composite samples KN3 and KN4 recorded higher impact strengths of 3.0 and 2.8 J, respectively, when compared with other hybrid counterparts. The tensile and flexural strengths of sample KN4 were 147.48 and 223.69 MPa, respectively. The tensile properties of various theoretical model were compared with experimental values.Peer reviewe

Effects of fiber loadings and lengths on mechanical properties of Sansevieria Cylindrica fiber reinforced natural rubber biocomposites

© 2023 The Author(s). Published by IOP Publishing Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY), https://creativecommons.org/licenses/by/4.0/In this present investigation, Sansevieria cylindrica fiber was used as a reinforcement in a natural rubber matrix. Various biocomposite samples with different fiber contents (lengths and loadings) were fabricated, using compression molding process and vulcanizing technique by maintaining the temperature around 150 °C. From the results obtained, mechanical properties: tensile strength, modulus elongation at break and tear strength of 10.44 MPa, 2.36 MPa, 627.59% and 34.99 N respectively, were obtained from the optimum composite sample with length and loading of 6 mm and 20 wt% composition, respectively. The maximum hardness was observed at 76.85 Shore A from the composite sample of 6 mm and 40 wt%. The optimum properties can be attributed to the presence of strong interfacial adhesion between the Sansevieria cylindrica fiber and the natural rubber matrix. The mechanisms of failure of the biocomposites at their interfaces were examined and analyzed, using scanning electron microscopy (SEM). The micrographs obtained from SEM further confirmed that the Sansevieria cylindrica fibers were surrounded with more amount of natural rubber which can exhibit strong interfacial bonding between fiber and matrix. The optimal composites of this work can be used in general, abrasion resistant conveyor belt.Peer reviewe

DNA adsorption studies of poly (4,4′-cychlohexylidene bisphenol oxalate)/silica nanocomposites

The present study deals with the synthesis, characterization, and DNA extraction of poly(4,4′-cyclohexylidene bisphenol oxalate)/silica (Si) nanocomposites (NCs). The effects of varying the monomer/Si (3.7%, 7%, and 13%) ratio towards the size and morphology of the resulting NC and its DNA extraction capabilities have also been studied. For the NC synthesis, two different methods were followed, including the direct mixing of poly(4,4′-cyclohexylidene bisphenol oxalate) with fumed Si, and in situ polymerization of the 4,4′-cyclohexylidene bisphenol monomer in the presence of fumed silica (11 nm). The formed NCs were thoroughly investigated by using different techniques such as scanning electron microscopy (SEM), fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), powdered X-ray diffraction (XRD), and Brunauer–Emmett–Teller (BET) analysis where the results supported that there was the successful formation of poly(4,4′-cyclohexylidene bisphenol oxalate)/Si NC. Within the three different NC samples, the one with 13% Si was found to maintain a very high surface area of 12.237 m2/g, as compared to the other two samples consisting of 7% Si (3.362 m2/g) and 3.7% Si (1.788 m2/g). Further, the solid phase DNA extraction studies indicated that the efficiency is strongly influenced by the amount of polymer (0.2 g > 0.1 g > 0.02 g) and the type of binding buffer. Among the three binding buffers tested, the guanidine hydrochloride/EtOH buffer produced the most satisfactory results in terms of yield (1,348,000 ng) and extraction efficiency (3370 ng/mL) as compared to the other two buffers of NaCl (2 M) and phosphate buffered silane. Based on our results, it can be indicated that the developed poly(4,4′-cyclohexylidene bisphenol oxalate)/Si NC can serve as one of the suitable candidates for the extraction of DNA in high amounts as compared to other traditional solid phase approaches

Review on Carbon Dioxide Utilization for Cycloaddition of Epoxides by Ionic Liquid-Modified Hybrid Catalysts: Effect of Influential Parameters and Mechanisms Insight

The storage, utilization, and control of the greenhouse (CO2) gas is a topic of interest for researchers in academia and society. The present review article is dedicating to cover the overall role of ionic liquid-modified hybrid materials in cycloaddition reactions. Special emphasis is on the synthesis of various cyclic carbonate using ionic liquid-based modified catalysts. Catalytic activity studies have discussed with respect to process conditions and their effects on conversion and product selectivity for the reaction of cycloaddition of CO2 with styrene oxide. The reaction temperature and the partial pressure of CO2 have found to play a key role in cyclic carbonate formation. The role of other influential parameter (solvent effect) is also discussed for the conversion of cyclic/aromatic oxides to polycarbonate production. Our own research work that deals with ionic liquid-based halide-modified mesoporous catalyst (MCM-41 type) derived from rice husk waste has also been discussed. Finally, the role of carbon dioxide activation and ring-opening mechanisms involved in the cyclic carbonate product formation from CO2 have been discussed

Drug delivery and antimicrobial studies of chitosan-alginate based hydroxyapatite bioscaffolds formed by the Casein micelle assisted synthesis

The present study aims to develop a hydroxyapatite (HAP) based scaffold composite for orthopaedic applications and for that, we adopt a Casein (Cs) micelle assisted synthesis route for the formation of a composite. Following the synthesis and characterization of various fluorine (2% and 5%) substituted HAPs (FHAP), they have been tested for the release of Ciprofloxacin (CIP) drug and antimicrobial efficacy. The physicochemical characterization such as FTIR and Raman confirms the successful formation of the HAP composites. Similarly, the powder XRD and FESEM analysis have used for the confirmation of crystallinity and morphological behaviour, respectively. The elemental composition has confirmed using EDX analysis. The antimicrobial studies indicate that the 5% FHAP sample is possessing superior antifungal and antibacterial activities and the highest activity has been observed against the gram-positive bacteria (Staphylococcus aureus) with an inhibition zone of 47 mm while the gram-negative bacteria (Escherichia coli) has only 38 mm inhibition zone. The CIP drug release profile has been controlling with the Cs/5% FHAP sample. Therefore, this composite has carried out for the scaffold formation with the use of chitosan-alginate matrices. Further, characterization of chitosan-alginate/5% FHAP scaffold composite indicates porous, biodegradable, considerable water uptake and retention ability, along with the maintenance of controlled CIP drug-releasing properties. Based on the analysis, the as-synthesized chitosan-alginate/5% FHAP scaffold composite can be suitable for the biomedical and bioengineering applications of bone tissue growth and as an implant

Evaluation of porogen factors for the preparation of ion imprinted polymer monoliths used in mercury removal

In the present study, ion imprinted polymer monoliths (IIPMs) were developed to overcome the limitations of ion imprinted polymer particles (IIPPs) used for the removal of Hg(II) ions from waste water samples. The adsorbents preparation, characterization and Hg(II) removal were very well reported. The IIPMs on porogen optimization was prepared using the molding technique with Hg(II) as a template ion, [2-(methacryloyloxy)ethyl]trimethylammonium cysteine (MAETC) as ligand, methacrylic acid (MAA) as functional monomer, ethylene glycol dimethacrylamide (EGDMA) as cross-linker, benzoyl peroxide as an initiator and methanol and acetonitrile as porogen in the polypropylene tube (drinking straw) as mold. The IIPMs prepared with higher volumes of porogen were indicated to have a good adsorption rate for the Hg(II) removal along with good water permeability and larger porosity as compared to a lower volume of porogen. The IIPMs prepared using the binary porogen were able to improve the porosity and surface area of the monolithic polymers as compared to the single porogen added IIPMs. Finally, we indicate from our analysis that the IIPM having the efficient capacity for the Hg(II) ions is easy to prepare, and has higher water permeability along with high porosity and high adsorption capacity and all these factors making it one of the suitable adsorbent for the successful removal of Hg(II) ions

Iminodiacetic acid modified kenaf fiber for waste water treatment

In the present study, iminodiacetic acid (IDA)-modified kenaf fiber, K-IDA formed by the chemical modification of plant kenaf biomass was tested for its efficacy as a sorbent material towards the purification of waste water. The K-IDA fiber was first characterized by the instrumental techniques like Fourier transform infrared (FTIR) analysis, elemental analysis (CHNSO), and scanning electron microscopy (SEM). On testing for the biosorption, we found that the K-IDA has an increment in the adsorption of Cu²⁺ ions as compared against the untreated fiber. The Cu²⁺ ions adsorption onto K-IDA fits very well with the Langmuir model and the adsorption maximum achieved to be 91.74 mg/g. Further, the adsorption kinetics observed to be pseudo second-order kinetics model and the Cu²⁺ ions adsorption is a spontaneous endothermic process. The desorption study indicates a highest percentage of Cu²⁺ of 97.59% from K-IDA under 1 M HCl solution against H₂SO₄ (72.59%) and HNO₃ (68.66%). The reusability study indicates that the efficiency did not change much until the 4th cycle and also providing enough evidence for the engagement of our biodegradable K-IDA fiber towards the removal of Cu²⁺ ions in real-time waste water samples obtained from the electroplating and wood treatment industries