Enhancement of the Photocatalytic Activity of MIL-53 Metal–Organic Frameworks Through the Addition of Reduced Graphene Oxide for Improved Degradation of Organic Dye Pollutants in Water Treatment Applications

Abstract

A simple nanocomposite consisting of MIL-53(Al) and reduced graphene oxide (rGO), denoted as MIL-53(Al)/rGO, was synthesized as a photocatalyst driven by sunlight and UV light to study the decomposition of methylene orange and methylene blue in aqueous solution. The MIL-53(Al)/rGO ultrafine particles were produced by an in situ method using the solvothermal technique. The nanocomposite was made with two different amounts of rGO, 2.5% and 5% by weight. Various tests, including XRD, N₂ adsorption-desorption isotherms, SEM, SEM-EDS, UV-Vis DRS (Diffuse Reflectance Spectroscopy), and FTIR, were performed on all photocatalyst variations to analyse their properties. Results from SEM and EDS showed the creation of small MIL-53(Al) particles measuring 10-20 ?m and rGO spread evenly on the MIL-53(Al) surface, particularly in the 2.5% rGO sample. The photocatalytic effectiveness of the MIL-53(Al)/rGO nanocomposites was tested for degrading organic dyes (MO and MB) in water under both sunlight and UV light for 60- and 120-minute durations. The 2.5% rGO photocatalyst showed the highest performance, removing over 96% and 98% of the dyes after one hour of sunlight exposure for MB and MO, respectively. This demonstrates that the combined effect of MIL-53(Al) and rGO composite can be seen as an effective photocatalyst for breaking down reactive dyes, such as MO and MB, in water treatment applications.

ABSTRAK: Kajian ini adalah berkaitan nanokomposit sederhana daripada MIL-53(Al) dan grafit oksida yang tereduksi (rGO), atau MIL-53(Al)/rGO, berjaya disintesis sebagai fotopemangkin oleh cahaya matahari dan cahaya UV bagi mengkaji penguraian metil jingga (MO) dan metilena biru (MB) dalam larutan akueus. Zarah ultrahalus MIL-53(Al)/rGO dihasilkan melalui kaedah in situ menggunakan teknik solvotermal. Nanokomposit dibuat dengan dua jumlah rGO berat berbeza, 2.5 wt% dan 5 wt%. Pelbagai ujian termasuk XRD, N₂ penyerapan-nyahserapan isoterma (BET), SEM, SEM-EDS, UV-Vis DRS, dan FTIR telah dilakukan pada semua variasi fotopemangkin bagi mengkaji sifatnya. Dapatan kajian dari SEM dan EDS menunjukkan penciptaan zarah kecil MIL-53(Al) berukuran 10-20 ?m dan rGO tersebar secara rata pada permukaan MIL-53(Al), terutamanya dalam sampel rGO 2.5%. Keberkesanan fotopemangkin nanokomposit MIL-53(Al)/rGO telah diuji bagi mengurai pewarna organik dalam air, di bawah kedua-dua cahaya matahari dan cahaya UV selama tempoh 60 dan 120 minit. Fotopemangkin rGO 2.5% menunjukkan prestasi tertinggi, dengan penyingkiran lebih dari 96% MB dan 98% MO, selepas pendedahan cahaya matahari selama satu jam. Ini menunjukkan, kesan gabungan komposit MIL-53(Al) dan rGO, boleh dilihat sebagai fotopemangkin yang berkesan bagi memecahkan pewarna reaktif, seperti MO dan MB, dalam aplikasi rawatan air.