In the present article, the synthesis of zeolite imidazole framework-11 (ZIF-11) by ultrasonic-assisted hydrothermal process and its application as an electrode modifier for electrochemical determination of uric acid in urine are demonstrated. The obtained materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and nitrogen adsorption/desorption isotherms. It was found that the ZIF-11 with rhombic dodecahedron topology and high surface area (1066 m2.g-1) was synthesized in a certain temperature and found in around 25–40°C, and other crystalline phases of zinc benzimidazolate deferring from ZIF-11 phase were found in less 25°C or higher than 40°C. The ZIF-11 is stable in the pH range 6-10. The modification of glassy carbon electrode was performed with ZIF-67 using the drop-casting procedure. The present ZIF-11 modified electrode was employed to study the electrochemical behavior of uric acid (UA). UA oxidation is catalyzed by this electrode in aqueous buffer solution (pH 7) with a decrease of 70 mV in overpotential compared to glassy carbon electrode. With the differential pulse–anodic stripping voltammetry (DP-ASV) method, the oxidation current of UA versus its concentration shows good linearity in the range 20–540μM ( R = 0.998 ) with a detection limit of 0.48 μM ( S / N = 3 ). The obtained ZIF-11 modified electrode was applied in the detection of UA content in urine samples, and satisfied results were obtained.

In the present paper, the composite of zeolite imidazolate framework-11 (ZIF-11) and activated carbon derived from rice husks (RHAC) was synthesized. The obtained materials were characterized by XRD, SEM, EDX-mapping, and nitrogen adsorption/desorption isotherms. The final composite ZIF-11/RHAC exhibits an even dispersion of ZIF-11 particles on activated carbon matrix. Herein, an electrochemical sensor based on a ZIF-11/RHAC was developed for a rapid determination of triclosan (TCS). It was found that the oxidation of TCS is irreversible and involves the transfer of one electron. The linear range for TCS detection in the optimized experimental conditions was found to be 0.1-8 μM with the limit of detection of 0.076 μM. Finally, the proposed method was successfully employed to detect TCS in different personal care product samples with high accuracy, which was confirmed by a good agreement between these results and those obtained using high-performance liquid chromatography (HPLC).

Porous TiO2/activated carbon (AC) material was synthesized by grafting peroxo-hydro titanium complexes to rice husk-derived activated carbon. It was found that the morphology of TiO2/AC consists of TiO2 fine particles highly dispersed on the AC matrix. The obtained TiO2/AC composites with high surface area and a red shift exhibit an excellent adsorption performance in both single and trinary system toward methylene blue (MB), methyl orange (MO), and methyl red (MR). The isotherm models including extended Langmuir, P-factor, ideal adsorbed solution theory (IAST) for Langmuir, Freundlich, and Sips models were applied to study the adsorption equilibrium data of trinary solutions. It was found that IAST for Freundlich and Langmuir models were the most suitable one to describe the adsorption of the three dyes on TiO2/AC material. The high maximum adsorption capacities (mmol g-1) in single/trinary mixture were found as 0.452/0.340 for MB; 0.329/0.321 for MO; and 0.806/2.04 for MR. Moreover, the recyclability experiments showed that the adsorbent could be reused through photocatalytic self-cleaning for at least three cycles with stable capacity. Thus, the TiO2/AC can be effectively employed for the removal of dyes from industrial textile wastewater.