Crystal violet dye removal from aqueous solution by electrocoagulation : bachelor thesis

Abstract

Uklanjanje boje Crystal Violet (CV) iz vodene otopine (4 ± 0.23 mg/L CV + 2 mg/L NaCl) procesom elektrokoagulacije (EK) provedeno je u dva smjera. U prvom slučaju promatran je utjecaj gustoće struje (0.016, 0.024 i 0.032 A/cm 2 ; pH = 3.2), dok je u drugom slučaju razmatran utjecaj početne pH vrijednosti (3.2, 5.5 i 7.0; i = 0.024 A/cm 2 ) na uklanjanje CV boje. Tijekom EK procesa, koji je trajao 50 minuta, promatrana je promjena pH, temperature, električne provodnosti te koncentracije CV boje. Učinkovitost uklanjanja CV boje EK procesom je izuzetno dobra. Pri tome, uklanjanje boje raste s vremenom trajanja procesa te porastom gustoće struje i porastom pH vrijednosti. Izuzetno dobri rezultati postignuti su primjenom najveće gustoće struje (potpuno uklanjanje nakon 40 min) te u slučaju početne pH vrijednosti od 5.5 (potpuno uklanjanje nakon 30 min). Tijekom EK procesa dolazi do potrošnje anodnog, ali i katodnog materijala. Potrošnja elektrodnih materijala se povećava s porastom gustoće struje i pH vrijednosti otopine pri čemu je utjecaj gustoće struje izraženiji. Izgled površina elektroda (snimljenih svjetlosnim mikroskopom) ukazuje na činjenicu da se anode tijekom EK procesa otapaju ravnomjerno i lokalno, dok katode uglavnom podliježu ravnomjernoj koroziji.The removal of the dye Crystal Violet (CV) from a aqueous solution (4 ± 0.23 mg/L CV + 2 mg/L NaCl) by the process of electrocoagulation (EC) was performed in two directions. In the first case, the influence of current density (0.016, 0.024, and 0.032 A/cm 2 ; pH = 3.2) was observed, whereas in the second case, the influence of initial pH (3.2, 5.5, and 7.0; i = 0.024 A/cm 2 ) on the removal of CV dye was considered. During the EC process, which lasted 50 minutes, changes in pH, temperature, electrical conductivity, and CV dye concentration were observed. The efficiency of CV dye removal by the EC process is extremely good. At the same time, the dye removal increases with the duration of the process and with the increase of the current density and pH of the solution. Extremely good results were obtained at the highest current density (complete removal after 40 min) and at an initial pH of 5.5 (complete removal after 30 min). During the EC process, anodic and cathodic material is consumed. The consumption of electrode material increases with the increase of current density and pH of the solution, with the influence of current density being more pronounced. The appearance of the electrode surfaces (taken with an light microscope) shows that the anodes dissolve uniformly and locally during the EC process, while the cathodes are mostly subject to uniform corrosion