Optical Absorption, Kinetics and Thermodynamic Studies of Pr(III) and Nd(III) Ions with N-Acetyl L-Cysteine in Presence of Ca(II) ions

Interaction of N-acetyl-L-cysteine (NAC) with Pr3+ (Pr(NO3)3·6H2O) and Nd3+ (Nd(NO3)3·6H2O) ions are studied in presence of Ca2+ (Ca(NO3)3·4H2O) ion in an aqueous and organic solvent by applying the spectroscopic technique for quantitative probe of 4f-4f transition. The complexation was determined by the variation in the intensities of 4f-4f absorption spectral bands and by applying the change of symmetric properties of electronic-dipole known as Judd-Ofelt parameters Tλ (λ = 2,4,6). On the addition of Ca2+ ion in the binary complexation of praseodymium and neodymium with N-acetyl-L-cysteine (NAC) there is an intensification of bands which shows the effect of Ca2+ toward the heterobimetallic complex formation. Other parameters like Slater-Condon (Fk), bonding (b1/2), the Nephelauxetic ratio (β), percentage covalency (δ) are also used to correlate the complexation of metals with N-acetyl-L-cysteine (NAC). With the minor change in coordination around Pr3+ and Nd3+ ions, the sensitivity of 4f-4f bands is detected and further used to explain the coordination of N-acetyl-L-cysteine (NAC) with Pr3+ and Nd3+ in presence of Ca2+. The variation in oscillator strength (Pobs), energy (Eobs) and dipole intensity parameter help in supporting the heterobimetallic complexation of N-acetyl-L-cysteine. In kinetics investigation, the rate of the complexation of both hypersensitive and pseudo-hypersensitive transition is evaluated at various temperature in DMF solvent. The value of the thermodynamic parameters such as ΔHo, ΔSo and ΔGo and activation energy (Ea) also evaluated.

Surface Functionalized Halloysite with N-[3-(Trimethoxysilyl)Propyl] Ethylenediamine for Chromium and Nickel Adsorption from Aqueous Solution

In this study, -[3-(trimethoxysilyl)propyl] ethylenediamine - modified Indonesian natural halloysite was applied for Cr(III) and Ni(II) adsorption from aqueous solution. The studies include the physicochemical characterization of the synthesized material by using XRD, SEM, gas sorption analyzer, and FTIR analyses. Furthermore, the adsorption experiments were performed at a batch system for investigating the adsorption kinetics and thermodynamic. The results showed no significant changes in either the material crystallinity or specific surface area, but the changes of surface functional groups identified the anchored ammine modifier. Kinetic modeling showed pseudo-second-order model best fitted the experimental data for both adsorbents. Moreover, the thermodynamic studies represented the chemisorption interaction of modified halloysite with the adsorbate since the average adsorption enthalpy values are at 44.3 kJ/mol and 41.70 kJ/mol for Cr(III) and Ni(II), respectively.

Quality assessment of drinking water of Multan city, Pakistan in context with Arsenic and Fluoride and use of Iron nanoparticle doped kitchen waste charcoal as a potential adsorbent for their combined removal

In majority cities of Pakistan, ground water is the main source of drinking water supply in the taps. Studies from different areas of Pakistan reported the presence of arsenic (As3/5+) and fluoride (F−) in drinking water supplies and can be envisaged as a deep-rooted cause of daily exposure of these in humans. The present study was planned with three way approach, i.e., to assess drinking water quality in Multan city, a highly populated and industrial activity area; synthesis of nano-adsorbent for simultaneous, effective and low-cost removal of fluoride and arsenic and manage waste by utilization of kitchen waste for synthesis of the nano-adsorbent. Out of 30 samples collected, 80% and 73% samples were found exceeding maximum residual limits (MRL) for F− and As3/5+, respectively, while 53% samples had both As3/5+ and F− concentrations greater than MRL. All these water samples were then treated with prepared nano-adsorbent, i.e., iron nanoparticles doped kitchen waste charcoal after evaluating the optimized experimental parameters and application of adsorption, kinetics and thermodynamic models. The nano-adsorbent showed high removal efficacy 81–100% for F− and 13–100% for As3+.