Rafaqat Ali Khan

Evaluation of electrical, dielectric and magnetic characteristics of Al–La doped nickel spinel ferrites

The paper reports the effects of lanthanum and aluminum ions, on the structural, electrical and magnetic properties of NiFe2O4 spinel ferrite nanoparticles. The precursors have been synthesized via a hydrothermal route in the presence of ascorbic acid (AA) using urea as a reducing agent and fuel for maintaining the uniform morphology and equal particle size distribution. In order to find out the optimum temperature (1023 K) for the formation of the spinel phase of the doped nickel ferrite, thermogravimetric analysis (TGA) for the un-annealed samples was performed. The X-ray diffraction patterns show that NiFe2−2xAlxLaxO4 have been well crystallized to spinel ferrite crystal structure with the Fd3m space group. The average crystallite size obtained is in the range of 9–19 nm, a size useful for attaining a suitable signal-to-noise ratio in high-density recording media and in electrical devices. In order to render the synthesized samples for diminishing eddy current losses, we were able to enhance the room temperature resistivity through proper selection of dopant used. The dielectric constant and dielectric loss decreased with applied frequency for all the samples showing normal behavior of ferrites. The calculated magnetic parameters such as saturation magnetization (Ms), remanence (Mr) and coercivity (Hc), showed increased values for some Al–La doped samples.

HYDROXYL RADICAL BASED DEGRADATION OF CIPROFLOXACIN IN AQUEOUS SOLUTION

This study reports the degradation of ciprofloxacin (CIP) by means of ionizing radiations. Kinetic studies with aqueous concentrations of 4.6, 10, 15, 17.9 mg/L reveals that degradation of CIP follows pseudo -first order kinetics and the decay constant increased with decrease in initial concentration of CIP. The removal efficiency, represented by G-value, decreased with increasing absorbed dose and increased with higher [CIP] 0 concentration at a given absorbed dose. The effects of bubbling CIP solution with N 2 , N 2 O or air on CIP degradation were also studied. The influence of various radical scavengers like tert -butanol, iso -propanol, HCO 3 - , CO 3 2- , NO 3 - and NO 2 - as radical scavengers in N 2 - saturated solutions of CIP indicated that •OH were more closely associated with the radiolytic decomposition of CIP than other radicals, such as e - aq or •H. The pH value of aqueous media played a crucial role in the degradation of CIP. It was observed that degradation efficiency was higher under acidic condition compared to degradation in natural or alkaline media. F - , CH 3 COO - and HCOO - were formed as a result of CIP degradation that were analyzed by ion-chromatography.

The interaction of a model active pharmaceutical with cationic surfactant and the subsequent design of drug based ionic liquid surfactants

Interactions of active pharmaceutical ingredients (API) with surfactants remain an important research area due to the need to improve drug delivery systems. In this study, UV-Visible spectrophotometry was used to investigate the interactions between a model low molecular weight hydrophilic drug sodium valproate (SV) and cationic surfactant cetyltrimethylammonium bromide (CTAB). Changes in the spectra of SV were observed in pre- and post-micellar concentrations of CTAB. The binding constant (Kb) values and the number of drug molecules encapsulated per micelle were calculated, which posed the possibility of mixed micelle formation and strong complexation between SV and CTAB. These results were compared to those of a novel room temperature surface active ionic liquid, which was synthesized by the removal of inorganic counterions from a 1:1 mixture of CTAB and SV. In this new compound the drug now constitutes a building block of the carrier and, as such, has considerably different surfactant properties to its building blocks. In addition, enhanced solubility in a range of solvents, including simulated gastric fluid, was observed. The study provides valuable experimental evidence concerning the performance of drug based surfactant ionic liquids and how their chemical manipulation, without altering the architecture of the API, leads to control of surfactant behavior and physicochemical properties. In turn, this should feed through to improved and controlled drug release rates and delivery mechanisms, and the prevention of precipitation or formation of polymorphs typical of crystalline form APIs.

The effects of nanoclay on thermal, mechanical and rheological properties of LLDPE/chitosan blend

Abstract The objective of this study was to prepare linear low density polyethylene (LLDPE)/chitosan/closite nanocomposites by using various concentrations of LLDPE, chitosan, and closite clay mineral. The nanocomposites were then characterized for their thermal, mechanical, and rheological properties by using different analytical techniques including thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), rheological characterization, tensile strength study, and scanning electron microscopy. The TGA demonstrated that crosslinked composites are thermally more stable than non-crosslinked composites. The DSC stated that the percentage crystallinity of crosslinked composites is lower than the non-crosslinked composites. It is also observed that the increasing quantity of chitosan and closite also reduces the percentage crystallinity of the prepared nanocomposites. Rheological characterization revealed that, crosslinked composites are viscoelastic in nature and have high complex viscosities (η*) and high dynamic shear storage modulus (G′), while non-crosslinked composites showed high dynamic shear loss modulus (G″). Tensile strength of crosslinked composites was much higher than non-crosslinked composites, however elongation at break (Eb) values of non-crosslinked composites are higher than crosslinked composites. The scanning electron microscopy displayed strong adhesion between matrix-filler-interphase in crosslinked composites, while some gaps were also observed in non-crosslinked composites. As a conclusion, chitosan, closite clay, and the LLDPE based nanocomposites with improved thermal, mechanical, and rheological properties can be successfully prepared by employing a peroxide-initiated melt compounding technique.

Restricted access-activated carbon clothes-based lead extraction from human serum: skipping the sample preparation step for biological media

ABSTRACT In this study, a new microextraction technique has been proposed which has the capability to extract lead (Pb) from human blood serum. Pb was directly extracted without any pretreatment step, whereas all the serum proteins were excluded. Initially, the surface of activated carbon cloths was decorated with bovine serum albumin using glutaraldehyde as cross-linker to prepare restricted-access-activated carbon cloths (RACCs). RACCs were then fixed in a filter holder to form a sorbent cartridge fixed at the tip of a syringe system coupled with electrothermal atomic absorption spectrometry. Experimental parameters that could possibly influence the extraction procedure were optimised. The limits of detection and quantification obtained were 1.9 and 6.3 μg L−1, respectively. Pb recoveries in fortified human serum samples were found in the range of 92.2–103.9%. The procedure was effectively used for Pb extraction in real samples devoid of any pretreatment step.

Sonochemically synthesized green sorbent for the simultaneous removal of trace metal ions: application and estimation of measurement uncertainty through bottom-up approach

Polyethyleneimine functionalized eggshell membrane (ESM–PEI) as a green biosorbent has been successfully utilized for the removal of toxic metals. ESM–PEI was sonochemically synthesized by cross-linking amine/amide functional groups of ESM with PEI using glutaraldehyde as a cross-linker. This overall functionalization was carried out in an ultrasonic bath. Surface modification of ESM–PEI was confirmed by Fourier transform infrared spectroscopy and scanning electron microscopy. All analytes were easily extracted by the ESM–PEI packed cartridge followed by spectrometric determination. After successful functionalization, the adsorption capacity of ESM–PEI improved almost 25 times over that of ESM. Different variables affecting the extraction efficacy were investigated. Under optimum conditions, the ESM–PEI packed cartridge showed good stability even after >70 adsorption/desorption cycles run while maintaining over 96% analyte recoveries. Validity of the proposed procedure was checked with certified reference materials as well as by assessing its precision (RSD values < 20%) and trueness (relative error < 11%) under day-to-day conditions. The developed procedure has been further validated by following ISO/IEC 17025 recommendations considering the possible uncertainties through a “bottom-up” approach. The proposed procedure was successfully applied to the environmental water samples for the extraction of Cu, Pb, Cd, and Ni, where ESM–PEI was found to be an environmentally friendly, economic, and more rugged biosorbent.

Comparative Studies on the Use of Binary and Ternary Combinations of Various Acidifying Agents for the Reduction of Soil pH

ABSTRACT The present study deals with the effects of addition of sulfur along with other acidifying agents for their ability to lower and maintain the pH in a given range for a longer period of time. The chemicals were subjected to batch test individually and in combinations. Treatments were applied to three soils of different textures: sandy clay loam, clay loam, and silt loam. A 1:1 soil/water paste along with the added amendment was maintained at room temperature for 2 months. Most of the chemical treatments lowered the pH significantly. Combinations containing S/Al2(SO4)3/H2SO4, S/Al2(SO4)3/H2O2, and S/H2O2/H2SO4 were found to be very effective in lowering the pH. The soil pH remained acidic for 2 months, indicating the suitability of chemically amended soil for the plantations requiring acidic soil pH.