LAUSR

Abstract Copper (II) was chelated with mono-, di- and tri-aminosilane functionalized graphene oxide (GO) and denoted as CAT1, CAT2, and CAT3. GO/Cu(II)-aminosilane complexes were characterized by Fourier transform infrared, X-ray diffraction, energy dispersive X-ray, thermogravimetric, and inductively coupled plasma, Brunauer-Emmett-Teller, transmission and scanning electron microscopy techniques. The Cu(II) to ligand ratio was found nearly fixed about the value of 1:2. The surface areas of CAT1, CAT2 and CAT3 were 61.14, 30.52, and 30.58 m 2  g −1 . Indigo carmine dye (IC), as a model, was subjected to oxidative degradation utilizing the immobilized complexes as catalysts and H 2 O 2 as an oxidant. The data were found to fit the second − order kinetics with respect to [IC]. Different from Fenton-like process, an enhancement in the activation of H 2 O 2 for oxidation was noticed in going from acidic to alkaline. Enthalpy–entropy compensation (EEC) between these heterogeneous systems has been discussed. The reactivity of the suggested chelation modes was arranged in the order; mode 1 > mode 2 > mode 3. A complete decolorization with 94.9% degradation of 10 −4  mol l −1 IC solution to inorganic end products at pH = 8 with H 2 O 2 of 0.025 mol l −1 in the presence 80 mg l −1 of CAT1 and a rate constant of 6.74 × 10 −2  l mol −1  min −1 was confirmed by total organic carbon (TOC) technique. Stability tests and the possibility of recycling approved the validity of the catalysts in the real environmental applications.