OPTIMIZATION OF THE ADSORPTION METHOD FOR PESTICIDE REMOVAL


Thesis Type: Postgraduate

Institution Of The Thesis: Erciyes University, Fen Bilimleri Enstitüsü, Turkey

Approval Date: 2022

Thesis Language: Turkish

Student: EMİNE YILMAZ

Supervisor: Filiz Dadaşer Çelik

Abstract:

The aim of this thesis is to examine the removal of metolachlor using four different activated carbons and to determine the conditions that will increase the removal efficiency. Experimental studies were carried out in two stages. In the first stage, methods were developed for the measurement of metolachlor in a High Performance Liquid Chromatography (HPLC) instrument by means of direct injection and liquid-liquid microextraction (DLLME). At this stage, the flow rate, temperature, mobil phase ratios, wavelength and analysis time were optimized by experimental studies. In the second stage, the removal of pesticides by adsorption using modified and unmodified activated carbons was studied and kinetic and isotherm tests were applied. In experimental studies, experimental design was made using the Taguchi method. The most suitable conditions determined in direct analysis were 20 minutes, 80% acetonitrile -20% pure water, 1.20 ml/min flow rate, 200 bar pressure and UV254 230 nm wavelength at 50 °C. It was carried out with a µL injector draw. With the most suitable conditions selected in direct analysis, the solvent type 1,2-dichloroethane, dispersive solvent type methanol, solvent volume 300 µL, dispersive solvent volume 1.0 mL were found for metolachlor by DLLME method. Considering the removal efficiencies in the kinetic tests, the time to reach the adsorption equilibrium phase was determined as 72 hours, and the pseudo-second order kinetic model better suited the adsorption process. According to the modified Freundlich isotherm model, the highest adsorption capacity among the capacities of activated carbons was obtained with AC Puriss activated carbon (106.7 mg/g), and the lowest adsorption capacity was obtained with Norit CA1 adsorbent (50.3 mg/g). In the tested activated carbon adsorption, as a result of the isotherm test with metolachlor, a removal efficiency of 90-99% was achieved with activated carbon at increasing doses.