Photocatalytic degradation of tetracycline using nanosized titanium dioxide in aqueous solution

Abstract

The aim of the study was to investigate the degradation kinetics of tetracycline antibiotic by nanosized titanium dioxide under ultraviolet irradiation. Enhancement of photocatalysis by addition of Hydrogen peroxide was also evaluated. Various experimental parameters such as initial tetracycline concentrations, initial titanium dioxide concentration, initial pH, reaction times, initial Hydrogen peroxide concentrations, as well as water matrix using ultrapure water, drinking water and secondary effluent were investigated. The initial rate of photocatalytic degradation of tetracycline well fitted the Langmuir-Hinshelwood kinetic model (R 2 = 0.9926) with a reaction rate constant of 1.4 mg/L min. The degradation rate depended on initial tetracycline concentration and initial pH. The degradation rate also increased with higher titanium dioxide density and reached a plateau at titanium dioxide concentration of 1.0 g/L. The tetracycline degradation rate was higher in drinking water compared to ultrapure water. The addition of Hydrogen peroxide to titanium dioxide suspension significantly enhanced the tetracycline degradation rate and substantially reduced the time required to degrade 100 % of tetracycline. Changes of chemical oxygen demand values during photolysis indicated that tetracycline transformed into intermediate products without complete mineralization. The ultraviolet visible spectra obtained before and after ultraviolet irradiation in the presence of titanium dioxide can indicate the formation of 4a,12a-anhydro-4-oxo-4-dimethylaminotetracycline.

Photocatalytic Performance of Titanates with Formula MTiO3 (M= Fe, Ni, and Co) Synthesized by Solvo-Combustion Method

“…This figure clearly indicates that the absorbance of the band located at 368 nm decreases with the reaction time indicating rupture of phenolic groups to aromatic rings B, also shows that the absorbance of the bands located at 270 nm decrease with reaction time, we can attribute this to the production of acylamino and hydroxyl groups. These results suggest that they are a by-product, which is more recalcitrant and therefore difficult to eliminate at 100% 30,31 .…”

Factors Influencing Imazapyr Herbicide Removal from Wastewater Using Photocatalytic Ozonation

“…Similar finding have been reported by Usharani et al, 14 and by Gar Alalma et al 15 These authors have reported first order reaction kinetics for the degradation and mineralization of chlorinated pesticides and insecticides and other various water pollutants by photocatalytic ozonation. [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33] The results, shown in figure 5, demonstrates that the optimal conditions for imazapyr degradation with photocatalytic ozonation is neutral pH. On the other hand, the combination of two oxidation systems, ozonation and photocatalysis, for water treatment under optimal conditions are reported to have increased oxidation efficiencies (synergy) compared to the sum oxidation efficiencies of these two oxidation systems separately.…”

“…A possible explanation resides in the fact that as imazapyr concentration rises, it is possible that more organic substances are deposed on the surface of TiO 2 , whereas less number of photons are available to reach the catalyst surface and the probability of reaction between imazapyr molecules and oxidizing species also decreases, thus resulting in less degradation percentage. [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32] …”

“…[10][11][12] However, The degradation of Imazapyr has also been investigated by other authors using photocatalysis and ozone and results showed lower concentration compared to photocatalytic ozonation. [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] The photocatalytic ozonation degradation of pesticides is largely dependent on operating parameters such as TiO 2 dosage, initial herbicide concentration and solution pH. [31][32] Understanding the effects of these factors on the photocatalytic degradation efficiency have an importance when designing a sustainable and efficient technique for wastewater treatment.…”

Metronidazole Removal Methods from Aquatic Media: A Systematic Review

“…The basis of photocatalytic reactions is that if the semi-conductive particles are irradiated with high-energy radiation, high-energy electron pairs and holes are formed; these generated electron pairs -holes are the initiator of oxidation -reduction process through the production of free radicals, and finally they lead to the mineralization of organic compounds emissions. One of the most important semiconductors is TiO 2 , which is an affordable, available, non-toxic, and very high performance semiconductor (18). Reyes et al (2006) studied the removal of tetracycline antibiotic using TiO 2 nanoparticles under UV irradiation and concluded that in general the use of photocatalytic refinement can be used as an interesting topic in degradation of tetracycline antibiotic and replacement of existing conventional.…”