FULL PAPER Degradation of hazardous organic dyes with solar‐driven advanced oxidation process catalyzed by the mixed metal– organic frameworks Alireza Farrokhi | Fahimeh Feizpour | Maryam Asaadzadeh Department of Chemistry, Faculty of Science, University of Birjand, Birjand 97179‐414, Iran Correspondence Alireza Farrokhi, Department of Chemistry, Faculty of Science, University of Birjand, Birjand, 97179‐414 Iran. Email: afarrokhi@birjand.ac.ir phosphonate‐based bimetallic metal‐ organic frameworks, namely STA‐12(M 1 , M 2 ) (M 1 ,M 2 = Mn, Fe, Co), show photocatalytic activity for the degradation of Rhodamine B (RhB) and Methylene blue (MB) from aqueous solution under natural sunlight irradiation. The degradation of the dyes, appears to be faster with STA‐12(Fe, Mn) than other synthesized MOFs. Thus, photo‐Fenton oxida- tive discoloration of dyes has been studied by H 2 O 2 catalyzed with the STA‐ 12(Fe, Mn). The process is first order with respect to dyes and the synergistic index in the STA‐12(Fe, Mn)/sunlight/H 2 O 2 system reached as high as 472%. Mineralization of dyes was discussed by spectroscopic and TOC measurement. Besides, the efficiency of STA‐12(Fe, Mn) used in photocatalytic process was attentively investigated through the characterization of reactive radicals, the stability and reusability of the photocatalyst, also the effect of operational parameters such as H 2 O 2 dosage, solution pH and initial dye concentration. This work demonstrates the first example of facilitating photo‐Fenton‐like excitation of H 2 O 2 via phosphonate based mixed metal organic frameworks as photocatalysts and explained a new opportunity for solar‐induced AOP envi- ronmental remediation and protection. KEYWORDS dye degradation, hydrogen peroxide, natural sunlight, phosphonate based MOFs, Photocatalysis 1 | INTRODUCTION Increasing worldwide contamination of water resources and decrease of water quality has become a drastic prob- lem in the human societies. The global increasing request for clean water has promote extensive research to achieve the modern methods for water treatment. [1] Among vari- ous biological, chemical, and physical technologies in con- tamination control, the advanced oxidation processes (AOPs), including ozonation, photocatalysis, sonolysis, Fenton reaction and their combination, have significant practical importance owing to their superior efficiency, easy handling, good reproducibility, and simplicity. [2] Generally, the AOP generates highly reactive oxidizing agents to degrade stable hazardous organic substances into less harmful molecules, even eventually mineralization of them to CO 2 and water. [3,4] Particularly, the application of a green oxidant, hydrogen peroxide (H 2 O 2 ), to produce highly reactive hydroxyl radical has triggered great atten- tion. Essentially, UV light irradiation, metal and nonmetal containing catalyst and ultrasonic irradiation could easily decompose H 2 O 2 to • OH radicals. [5–9] But, most of these methods require long runtimes, hard operating pH range and high energy consumption. Therefore, extensive research effort has been devoted to progress a heteroge- neous catalytic method activating H 2 O 2 to overcome the Received: 1 November 2018 Revised: 29 January 2019 Accepted: 11 March 2019 DOI: 10.1002/aoc.4928 Appl Organometal Chem. 2019;e4928. https://doi.org/10.1002/aoc.4928 © 2019 John Wiley & Sons, Ltd. wileyonlinelibrary.com/journal/aoc 1 of 11