Degradation reaction of Diazo reactive black 5 dye with copper (II) sulfate catalyst in thermolysis treatment

• Published in: Environmental science and pollution research international 2018-03, Vol.25 (7), p.7067-7075
• Main Authors: Lau, Yen-Yie, Wong, Yee-Shian, Ang, Tze-Zhang, Ong, Soon-An, Lutpi, Nabilah Aminah, Ho, Li-Ngee
• Format: Article
• Language: English
• Subjects: Aquatic Pollution; Atmospheric Protection/Air Quality Control/Air Pollution; Azo dyes; Benzene; Bond strength; Bonding strength; Catalysis; Catalysts; Chemical bonds; CI Reactive Black 5; Color; Color removal; Copper; Copper sulfate; Decomposition; Decomposition reactions; Degradation; Dyes; Earth and Environmental Science; Ecotoxicology; Enthalpy; Environment; Environmental Chemistry; Environmental Health; Environmental science; Intermediates; Molecular structure; Naphthalene; Research Article; Rubidium; Sulfates; Thermal energy; Waste Water Technology; Water Management; Water Pollution Control; Zeta potential
• ISSN: 0944-1344; 1614-7499
• DOI: 10.1007/s11356-017-1069-9

The theme of present research demonstrates performance of copper (II) sulfate (CuSO 4 ) as catalyst in thermolysis process to treat reactive black 5 (RB 5) dye. During thermolysis without presence of catalyst, heat was converted to thermal energy to break the enthalpy of chemical structure bonding and only 31.62% of color removal. With CuSO 4 support as auxiliary agent, the thermally cleaved molecular structure was further destabilized and reacted with CuSO 4 . Copper ions functioned to delocalize the coordination of π of the lone paired electron in azo bond, C=C bond of the sp 2 carbon to form C-C of the sp 3 amorphous carbon in benzene and naphthalene. Further, the radicals of unpaired electrons were stabilized and RB 5 was thermally decomposed to methyl group. Zeta potential measurement was carried out to analyze the mechanism of RB 5 degradation and measurement at 0 mV verified the critical chemical concentration (CCC) (0.7 g/L copper (II) sulfate), as the maximum 92.30% color removal. The presence of copper (II) sulfate catalyst has remarkably increase the RB 5 dye degradation as the degradation rate constant without catalyst, k 1 is 6.5224 whereas the degradation rate constant with catalyst, k 2 is 25.6810. This revealed the correlation of conversion of thermal energy from heat to break the chemical bond strength, subsequent fragmentation of RB 5 dye molecular mediated by copper (II) sulfate catalyst. The novel framework on thermolysis degradation of molecular structure of RB 5 with respect to the bond enthalpy and interfacial intermediates decomposition with catalyst reaction were determined.