Photocatalytic removal of cyanide with illuminated TiO2

Abstract

Effects of TiO(2) dosage, pH and initial cyanide concentration on the removal efficiency of cyanide from aqueous solutions with illuminated TiO(2) have been investigated. Adsorption and oxidation were recognized as significant processes for the elimination of cyanide. From the Langmuir isotherm, the maximum adsorption capacity was determined as 17.24 mg/g at pH 7. Adsorbed amount of cyanide slightly increased as the TiO(2) dosage increased. However, as no significant increase was observed above 1 g/L TiO(2), an optimum TiO(2) dosage was determined as 1 g/L. Photocatalytic oxidation efficiency of cyanide was greatly affected by the solution pH. It increased as the solution pH decreased. The photocatalytic oxidation efficiency after 120 min was 80.4% at pH 3 while it was only 20.4% at pH 11. Photocatalytic oxidation of cyanide was well described by the second-order kinetics. Photocatalytic reaction with illuminated TiO(2) can be effectively applied to treat industrial wastewater contaminated with cyanide.

Effect of organic matter on cyanide removal by illuminated titanium dioxide or zinc oxide nanoparticles

“…HA, oxalate, EDTA, NTA and phenol were used as organic matter. TiO 2 and ZnO dosage equal to 1 g/L was used for all experiments because this dosage was identified as an optimum dosage from our previous paper [2,17]. The initial solution pH was adjusted by adding 0.1 M NaOH and HCl.…”

“…Cyanide (CN) is a highly toxic component, which is generated from several industrial activities such as gas production, pharmaceutical, mining, electroplating processes and coal gasification [1,2]. It is known that wastewater generated from electroplating industry contains high concentration of cyanide [3].…”

“…The toxicity of CNCl may exceed that of equal concentrations of cyanide. At an alkaline pH, CNCl hydrolyzed into the cyanate ion (CNO – ), which has only limited toxicity [1,2]. …”

Cobalt-doped ZnS-reduced graphene oxide nanocomposite as an advanced photocatalytic material

“…Many researchers have studied different techniques for the removal of dyes from wastewater, including nanofiltration [5,6], coagulation/flocculation [7,8], micellar enhanced ultrafiltration [9], oxidation [10][11][12], ozonolysis [13][14][15], the use of activated carbon [16,17] and biological treatment techniques [18,19]. However, these conventional wastewater treatment techniques are either expensive or a lot of wastes are generated during the purification process, which limits their application.…”

Application of Semiconductor Photocatalytic Materials for the Removal of Inorganic Compounds from Wastewater

“…Table 7.2 summarizes the application of semiconductor materials for the photocatalytic removal of cyanide species. The use of TiO 2 in the slurry form for the photocatalytic degradation with artificial UV light of both free and complex cyanide compounds has been extensively investigated (L opez-Muñoz et al 2009;Marugan et al 2008;Osathaphan et al 2013;Siboni et al 2011b). Lopez Muñoz carried out the removal of Ag(CN) 2 À in the presence of oxygen using the TiO 2 photocatalytic treatment.…”