Ertugay, Neşe; Keleş Güner, Eda

This study investigates, for the first time, the potential of Thuja plicata (TP) cone-derived activated carbon for the removal of the azo dye Reactive Red 2 (RR2) from aqueous solutions. Activated carbon was produced via microwave irradiation to enhance the adsorption capacity of the raw material. The prepared activated carbon (TPAC), synthesised using a chemical activating agent, was characterised by Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX), and Fourier Transform Infrared Spectroscopy (FTIR). SEM analysis demonstrated that TPAC exhibited increased surface porosity and an irregular morphology after adsorption at the optimal pH. EDX results confirmed that carbon and oxygen were the dominant elements, with elevated contents post-activation. BET analysis indicated a decrease in the specific surface area from 66.64 to 20.35 m2 g−1 after RR2 adsorption, likely due to pore blockage. Batch adsorption experiments were conducted to evaluate the influence of several parameters, including solution pH, adsorbent dosage, initial dye concentration, and temperature. The maximum removal efficiency (54%) was achieved at pH 3 with an adsorbent dosage of 0.01 g. The adsorption capacity increased with rising dye concentration, reaching a maximum of 309.56 mg g−1 at 60 mg L−1. Adsorption isotherms, kinetics, and thermodynamic properties were also evaluated. The Freundlich isotherm model exhibited the best fit to the equilibrium data, indicating multilayer adsorption on a heterogeneous surface. Kinetic data were best described by the pseudo-second-order model, suggesting that chemisorption was the rate-limiting step. Thermodynamic analysis confirmed that the adsorption of RR2 onto TPAC was a spontaneous and exothermic process.

Yavuz, Sevtap Caglar; Yavuz, Emre; Ozdokur, Kemal Volkan

In the present work, ZnMoO4/Ag2WO4 nanocomposite was synthesized via facile hydrothermal and chemical precipitation method for determination of photocatalytic performance on organic contaminants such as methylene blue and trimethoprim. The synthesized nano-photocatalyst was characterized using various instrumental techniques. Photocatalytic degradation of methylene blue and trimethoprim by the samples was realized under UV light irradiation. The obtained results demonstrated that photocatalytic degradation of methylene blue by ZnMoO4/Ag2WO4 was 99.6% in 30 min. The bare ZnMoO4 produced 57.8% and Ag2WO4 produced 76.7% photocatalytic degradation of methylene blue in 60 min. The synthesized ZnMoO4/Ag2WO4 nanocomposite, about which there is little information on remediation of organic pollutants, had possessed the outstanding photocatalytic degradation performance on methylene blue and trimethoprim due to pseudo first order kinetic.

Kuşcu, Ceren; Özdokur, K. Volkan; Koçak, Süleyman; Ertaş, F. Nil

Recently, cobalt oxides attract a special attention mainly due to their excellent electrocatalytic activity towards various compounds. This study concerns with electrochemical preparation of cobalt oxide modified glassy carbon electrodes decorated with platinum nanoparticle in the pursuit of its catalytic applications. The parameters affecting the deposition conditions have been evaluated by monitoring oxygen reduction reaction (ORR) in pH 5.0 acetate buffer. Under optimal conditions, the composite film electrode surface was utilised as a platform forbiosensor development. Polyphenol oxidase enzyme was immobilised onto the electrode surface for phenol detection, and the influence of solution and operational parameters have been investigated. The medium pH and the enzyme amount have been optimised as pH 7.0 and 0.3 mg, respectively. Chronoamperograms were recorded for phenol detection in micromolar levels.

Cubuk, Osman; Colak, Isıl; Özdokur, Kemal Volkan; Caglar, Bulent; Coldur, Fatih; Topcu, Cihan

A voltammetric carbon paste sensor (CPS) was described for the detection of chlorite ion in water analysis. For the construction of the voltammetric CPS, organo-bentonites were synthesised by intercalation of N-cetylpyridinium (NCP) at different amounts into interlayer gap of bentonite. Some features of the obtained organo-bentonites such as structural, thermal and morphological were investigated by using various techniques. Afterwards, the voltammetric behaviour of the (Formula presented.) solution was investigated with cyclic voltammetry in the potential range of 0.0–1.0 V at a scan rate of 50 mV s−1 based on the obtained organo-bentonites as electroactive material. The characterisation of the prepared organo-bentonites as electroactive material, the effect of the amount of NCP–bentonite (NCP–B) in modified CPS on the 10.0 mM CIO2- response was tested by chancing the percentage of NCP–B in the range of 2.50–12.50% under identical experimental conditions. The pH of the measurement cell was optimised by using 0.04 M Britton–Robinson buffer in the range of pH 2.0–12.0. Under the optimised conditions, developed sensor exhibited a linear response in the range of 2.0 × 10−5 to 2.0 × 10−4 M chlorite ions concentrations. The detection limit and the limit of quantification were figured out as 6.0 × 10−6 and 2.0 × 10−5 M, respectively. The repeatability and reproducibility of the sensor were calculated as 5.0% and 6.8% (N = 5), respectively. Finally, the sensor was successfully applied for the analysis of bottled water, and the mean recovery was found as 103 ± 3%.