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In this study, reduced graphene oxide (RGO)-decorated Co3O4 nanorods were synthesized via a hydrothermal method and characterized for supercapacitor applications. XRD, FTIR, Raman, SEM, HRTEM, and XPS analyses confirmed the successful formation of pure-phase cubic Co3O4 and the effective integration of RGO. Among the samples, Co3O4@180 °C showed the highest crystallinity and was selected for RGO decoration. The RGO/Co3O4@180 °C nanocomposite exhibited superior electrochemical performance due to synergistic effects between the pseudocapacitive Co3O4 nanorods and the high conductivity of RGO. Cyclic voltammetry and galvanostatic charge–discharge tests revealed a specific capacitance of 710 F/g at 10 mV/s and 681 F/g at 2 A/g for the RGO/Co3O4@180 °C electrode. The enhanced performance is attributed to improved electron transport, higher surface area, and better electrolyte accessibility provided by RGO.
The recent research work presents a modified Poly tetrafluoroethylene (PTFE) cross-linked chitosan membrane (mPTFECs) as an effective adsorbent for the removal of fluoride (F-) ions from aqueous systems. The batch adsorption process was statistically enhanced and validated using Response Surface Methodology. The maximum capacity of the mPTFECs for F- was calculated to be 42.71 mg g- 1, showing high affinity of mPTFECs for F- . The data for adsorption in equilibrium were found to fit the Langmuir isotherm (R2 = 0.994) which indicates a monolayer adsorption on a homogeneous surface. Results of the kinetics study revealed that F- adsorption was best explained by pseudo-second-order (R2 = 0.995). Thermodynamic studies indicate that F- adsorption onto mPTFECs is spontaneous as well as exothermic and driven by enthalpy. The membrane's effectiveness was further tested on real water samples in actual conditions. Moreover, regeneration studies indicated that after five successive adsorption-desorption cycles, the membrane maintained significant adsorption performance, indicating its reusability and cost-effectiveness. The potential of mPTFECs as an effective and sustainable adsorbent for adsorption removal is highlighted in the study.
The Barzilai–Borwein (BB) method is R-linearly convergent on strongly convex quadratics, although neither the objective value nor the gradient norm is generally monotone. We construct an explicit current-point Lyapunov function for the quadratic dynamics after the warm-up step, assuming that both endpoints of the initial active spectrum survive this step. If a<b are these endpoints and P_a,P_b are the corresponding spectral projectors, then f(x) :=‖ P_a∇ f(x)‖^2b/a+b‖ P_b∇ f(x)‖^2a/a+b satisfies, for BB1, BB2, and every fixed positive weighted delayed Rayleigh rule, f(x_k+1) =(b-a/b+a)^2 e^-2D_a,b(τ_k)f(x_k), D_a,b(τ_k)≥0, where τ_k=1/α_k is the reciprocal step. The function is obtained by denormalizing the endpoint coboundary certificate in the sharp-rate analysis of Yang and Yuan. We prove that the endpoint exponents are the unique minimax choice among endpoint monomials and illustrate the Lyapunov law on a nonmonotone BB1 trajectory. Using this law, we also give a proof of R-linear convergence of the method in finite dimensions.
The effective removal of synthetic dyes from wastewater remains a significant challenge in environmental remediation due to their complex molecular structures and resistance to biodegradation. In the present study, Zeolitic Imidazolate Framework-67 (ZIF-67) was successfully synthesised via the co-precipitation method and evaluated for the effective adsorption of cationic crystal violet (CV) dye from aqueous solutions. The synthesised composite was comprehensively characterized using several analytical and electron microscopic techniques, viz., XRD, FTIR, SEM-EDS, BET, zeta potential, and pHpzc, confirming its structural, morphological, and surface characteristics. Under optimized conditions (CV concentration: 50 mg L−1, adsorbent dose: 10 mg, pH: 7.0, and contact time: 60 min), ZIF-67 exhibited the maximum adsorption capacity of 698.9 mg g−1. This high adsorption efficiency was attributed to the crystalline nature and large specific surface area of 367.1 m2 g−1. Equilibrium adsorption data were best described by the Freundlich isotherm model, whereas the adsorption kinetics followed the pseudo-second order model. Thermodynamic analysis revealed that the resulting adsorptive mechanism was spontaneous, endothermic, and entropy-driven. Furthermore, the optimal conditions for the batch adsorption experiments were validated using response surface methodology. These findings demonstrate that ZIF-67 is a promising adsorbent for the efficient decontamination of CV from wastewater.
A novel cleft-type cholic acid dimer was synthesized from native bile acid through a six-step reaction sequence. Structural characterization was performed using FTIR, 1D NMR (1H, 13C and DEPT135), 2D NMR (1H,1H COSY; 1H,13C HSQC; 1H,13C HMBC) and ESI-MS (+). The dimer could entrap both polar and nonpolar guests within its invertible pockets, adapting to changes in solvent polarity. Specifically, UV-Vis absorption and in silico simulations revealed a moderately stable 1:1 host-guest complex for the dimer with Cresol Red sodium salt in an organic solvent. The docked dimer-pyrene complex, investigated by molecular modeling studies, demonstrated an identical 1:1 binding ratio and moderate stability in the micromolar concentration range. Steady-state fluorescence investigations implied that the quenching of pyrene emission by the dimer in an aqueous environment was chiefly a collisional or dynamic pathway rather than the generation of a ground-state dimer-pyrene assembly.
