UV-Based Advanced Oxidation Processes of Remazol Brilliant Blue R Dye Catalyzed by Carbon Dots.

UV-based advanced oxidation processes (AOPs) (UV/H 2 O 2 and UV/S 2 O 8 2- ) with a titanium(IV)-doped carbon dot, TiP-CD, as a catalyst were developed for the decomposition of Remazol Brilliant Blue R (Reactive Blue 19), an anthraquinone textile dye (at T = 25 °C and pH = 7). The Ti-CD, with marked catalytic UV properties, was successfully synthesized by the one-pot hydrothermal procedure, using L-cysteine as carbon precursor, ethylenediamine as nitrogen source, PEG (polyethylene glycol) as a capping agent, and titanium(IV) isopropoxide (precursor of TiO 2 doping). Contrary to azo dyes (methyl orange, orange II sodium salt, and reactive black 5), which achieved complete degradation in a time interval less than 30 min in the developed AOP systems (UV/H 2 O 2 , UV/S 2 O 8 2- , and UV/TiO 2 ), the RBB-R showed relatively low degradation rates and low discoloration rate constants. In the presence of the catalyzer, the reaction rate significantly increased, and the pseudo-first-order rate constants for the RBB-R discoloration were UV/3.0 mM H 2 O 2 /TIP-CD-0.0330 min -1 and UV/1.02 mM S 2 O 8 2- /TIP-CD-0.0345 min -1 .