In recent years, the interest in waste water treatment increased to preserve the environment. The objective of this study is the removal of lead and cadmium ions from aqueous solution by treated Phragmites biomass (TPB). TPB was characterized by using Fourier transform infrared spectroscopy (FTIR) and energy dispersive X-ray analysis (EDS) which indicates the presence of functional groups that may be responsible of metal adsorption such as hydroxyl, carbonyl, sulfonate and carboxylate. Characterization by scanning electron microscopy (SEM) and surface area analysis using the Brunauer–Emmett–Teller method (BET) illustrated that TPB is nonporous with a small surface area. The influences of various experimental factors were investigated; the proposed method recommended the extraction of Pb+2 and Cd+2 metal ions by TPB at pH 5.0. A contact time of 60 and 45 min was required for the adsorption 50 mL (50 ppm) Pb+2 and Cd+2 respectively to reach equilibrium when 0.10 g TPB was used. The optimum TPB dosage was 0.20 g for adsorption both metal ions when adsorbate solution was 50 mL (50 ppm). Particle sizes of 0.125–0.212 mm showed the best metal ion removal of both metal ions. Thermodynamic study illustrated that both metal ions correlate more with Langmuir isotherm. Furthermore, chemisorption of Pb+2 and Cd+2 on TPB was more likely according to kinetic study data.
A series of batch lab-scale experiments were performed to investigate the performance of dead phosphorylated algal biomass of Spirogyra species for the bioadsorption of Cu +2 ions from aqueous solutions. FT-IR and SEM analyses were performed to characterize the phosphorylated and raw algae. The SEM analysis indicated that the phosphorus content increases by about 5 times. The isotherm equilibrium data indicated that phosphorylation enhances the removal of Cu +2 from water by about 20%. The experimental isotherms fit well to Langmuir models with R 2 values close to 0.99.Adsorption kinetic study was conducted to investigate the effect of initial Cu +2 concentrations, pH, and adsorbent dose on the loading capacity of algal biomass. The optimum pH for the process was around 6 and the corresponding maximum loading capacity was 65 mg/g. The pseudo second-order kinetics successfully modeled the kinetic results with R 2 values closed to 0.99. The thermodynamic results indicated that the bioadsorption process is endothermic and spontaneous at initial Cu +2 concentrations lower than 100 mg/L. The results were promising and encourage the design of a continuous process using algal biomass to remediate water polluted with heavy metals.
Purpose: To determine vildagliptin concentration in a pharmaceutical formulation using voltammetric analysis techniques, and optimize the parameters affecting the techniques. Method: Four types of voltammetry techniques, including cyclic voltammetry (CV), differential pulse voltammetry (DPV), square wave voltammetry (SWV), and linear sweep voltammetry (LSV), were employed to measure vildagliptin. Platinum (Pt) and glassy carbon (GC) were used as working electrodes, while KNO3 (1 M) and phosphate buffer (NaH2PO4/H3PO4) pH 6.8 were used to study optimal voltammetric analysis conditions. Results: CV results indicate that vildagliptin is electroactive and exhibits irreversible redox cycles while LSV results showed an oxidation peak current around 1.35 V that has high sensitivity and a linear standard regression line correlation coefficient of 0.9995. In addition, LSV results showed that vildagliptin has a lower limit of detection of ~ 0.241 mM and a limit of quantification of ~ 0.802 mM. Finally, the results show that vildagliptin has an acceptable level of recovery of 104.1 % and a relative standard deviation of 0.52 % for the commercially available vildagliptin tablets used in this study. Conclusion: The accuracy and precision of all applied voltammetric techniques for vildagliptin analysis are within accepted limits stipulated in pharmaceutical analysis quality control guidelines. The recommended method for vildagliptin analysis is LSV with Pt as the working electrode and KNO3 (1 M) as the supporting electrolyte.
Cladophora biomass has been treated and used for the removal of Lead and Cadmium ions from water, and the characterization of Cladophora biomass by Fourier transform infrared (FTIR) and energydispersive x-ray analysis (EDS) indicate the presence of functional groups of different components such as polysaccharides, amino acids, fatty acids and others. Scanning electron microscopy (SEM) and surface area analysis (BET) confirm nonporous algal biomass with small surface area. The parameters affecting metal ions removal from water such as adsorbent-solution contact time, pH of metal ion solution, algal biomass dose and mesh sizes have been studied. Isothermal study has been applied using Freundlich and Langmuir models.
In the present work TiO 2 nanotubes (TNT) have been synthesized by alkaline hydrothermal transformation. Then they have been doped with Gd element. Characterizations of doped and undoped TNT have been done with TEM and SEM. The chemical composition was analyzed by EDX, Raman and FTIR spectroscopy. The crystal structure was characterized by XRD. Carbon paste electrode has been fabricated and mixed with Gd doped and undoped TNT to form a nanocomposite working electrode. Comparison of bare carbon paste electrode and Gd doped and undoped TNT carbon paste electrode for 1.0 ×10 −3 M K 4 [Fe(CN) 6 ] voltammetric analysis; it was observed that Gd doped TNT modified electrode has advantage of high sensitivity. Gd doped TNT modified electrode has been used as working electrode for itopride assay in a pharmaceutical formulation. Cyclic voltammetry analysis showed high correlation coefficient of 0.9973 for itopride (0.04-0.2 mg/mL) with a limit of detection (LOD) and limit of quantitation values (LOQ) of 2.9 and 23.0 µg.mL −1 respectively.
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