ABSTRACTIn this work, the micro powder was the product of cedar leaf (MPCL) is used as a low-cost adsorbent for the removal of Pb2+ ions from aqueous solutions. Bath experiments were used to determine the best adsorption conditions The adsorption percentage of Pb2+ ions MPCL samples at different initial pH, contact time (tc), adsorbent dosage and temperature (T) were investigated. Effective removal of metal ions was demonstrated at pH values of 5. Metal adsorption onto MPCL was evaluated by Langmuir and Freundlich isotherms. Results indicate that the Langmuir isotherm model is the most suitable one for the adsorption process using MPCL (R2=0.9987), thus indicating the applicability of monolayer coverage of Pb(II) ion on MPCL surface. The relationship between thermodynamic parameters was used to predict the absorption process. According to Thermodynamic analysis, the process exothermic and natural (ΔHo= -21.65 kJmol-1 and ΔSo = - 56.4 kJmol-1 K-1).Keywords: Pb2+; adsorption; micro powder; cedar leaf; Thermodynamic; MPCL پرونده مقاله

In this study, the electrochemical determination of oxazepam in plasma samples was studied. The composite of graphene oxide/boron (B-RGO) was synthesized via the hydrothermal method and it was cast on the glassy carbon electrode (GCE). The polyaspartic acid (poly(ASP)) was deposited on the B-RGO by electropolymerization to prepare the modified electrode named B-RGO/ poly(ASP)|GCE. The B-RGO and B-RGO/poly ASP were characterized using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Electrochemical studies were performed by cyclic voltammetry (CV), linear sweep voltammetry (LSV) and differential pulse voltammetry (DPV) methods. The experimental parameters affecting the reduction of oxazepam such as pH, preconcentration time, scan rate and other analysis conditions, and instrumental parameters were optimized. Under the optimal conditions, the linear range was obtained from 0.001 to 800 μM with a correlation coefficient of 0.998. The repeatability of the method for the electrode to electrode and one electrode were 4.3% and 4.9%, respectively. The limit of detection (LOD) of 0.3 nM and the limit of quantitation (LOQ) of 1 nM were obtained. The high efficiency of the developed electrode in the determination of oxazepam in the plasma sample was proved by using acceptable results and satisfactory relative recovery percentage (>90%). Based on our calculation, the heterogeneous electron transfer rate constant (ks) was 1.92 s-1. The interaction between oxazepam and modifier was single-layer and multi-layer adsorption, respectively in low and high concentrations. پرونده مقاله