OICC Press Iranian Journal of Catalysis 2345-4865 12 2 2022 06 05 Transition-metal modified mesoporous silica nanoparticles as highly effective heterogeneous catalysts for discoloration of Basic red 5 in aqueous solution 10.30495/ijc.2022.1949927.1911 EN Fatemeh Mahfoozi Faculty of Chemistry, North Tehran Branch, Islamic Azad University, Hakimiyeh, Tehran, Iran 0000-0002-7992-346X Ali Mahmoudi Faculty of Chemistry, North Tehran Branch, Islamic Azad University, Hakimiyeh, Tehran, Iran 0000-0002-7992-346X Mohammad Reza Sazegar Faculty of Chemistry, North Tehran Branch, Islamic Azad University, Hakimiyeh, Tehran, Iran. Khodadad Nazari Future Bioenergy Solutions Inc., North Vancouver, BC, V7P 3P9, Canada Journal Article 2022 06 05 Mesoporous silica nanoparticles (MSNs) were synthesized hydrothermally and modified with Co2+ and Zn2+. The as-prepared samples were denoted as MSN, Co-MSN(X), and Zn-MSN(X), where X is the Si/M molar ratio. In addition, co-modified MSN samples with both cations were also prepared and denoted as Co-Zn(Y)-MSN(X), where Y indicates the Zn2+ content in the range of 1-7 wt.% relative to Co2+. Correctness of the anticipated structures was approved by FTIR, XRD, SEM, EDX, BET, and XRF analyses. It was found that Co-Zn(7)-MSN(75) can be used as an efficient photocatalyst for discoloration of basic red 5 under very mild conditions. Up to 86% of basic red 5 was discolored after 3.75 h under the optimized conditions including catalyst dosage of 0.025 mg mL-1, pH=7, and irradiation of 4×8 W UV (254 nm) lamps. By using the Langmuir–Hinshelwood kinetics model, it was found that the reaction followed a pseudo-first-order kinetic. Highlights Mesoporous silica nanoparticles were co-modified with Co2+, and Zn2+. The product was denoted as Co-Zn(7)-MSN(75), with Si/Co= 75 and Zn/Co= 7 %. Co-Zn(7)-MSN(75) showed high photocatalytic activity in discoloration of neutral red. The optimized conditions include pH 7, 0.025 mg of catalyst, 0.5 M H2O2, and 32 W UV. 86% of neutral red was discolored under very mild conditions within 225 min.