## 1 Introduction  
The polymeric membrane filtration technique is a widely practiced strategy for the removal of environmental contaminants from water. This is because it is an energy-efficient procedure that is effective even at low concentrations of water contaminants [1]. Moreover, a lot of the polymeric membranes known have high mechanical strength, good thermal and chemical stability, acid and alkaline resistance, and they are cheap to make [2]. However, the industrial application of cellulose acetate based membranes, in particular, is restricted because they are super-hydrophobic, and that membrane fouling occurs quickly. The consequences of their hydrophobicity and propensity to fuel are that their separation efficiency is reduced and so is their water flux, resulting in high electrical energy consumption (E\({}_{\text{EC}}\)) as high pressure is required. Additionally, this leads to high running expenses and the lifespan of the membranes is significantly reduced [3]. Attempts have been made to regenerate membranes, but these processes usually involve the use of harsh chemicals and/or physical and electrical processes that can damage and contaminant the membrane [4]. The employment of microfiltration membrane (MF, 100-1000 nm pore sizes) is of interest recently for the eradication of micropollutants, whereas ultrafiltration (UF) (5-50 nm), nanofiltration (NF) (2-5 nm) [5], are mainly utilized to reject small solutes at high pressures (100-1000 psi) as compared to MF membranes [6]. MF membranes coupled with photocatalysis offer numerous advantages, such as simultaneous degradation and rejection of contaminants, preventing catalyst detachment, easy to recycle and reuse, controllable process relation to flow rate and filtration efficiency and compatibility with various reactors. Perhaps the biggest problem with membrane technology for water purification is that the process generates sludge which is difficult and expensive to dispose of [4]. One of the strategies used to overcome setbacks associated with membrane technology is to integrate the membrane filtration process and with nanomaterials with photocatalytic properties. This process equips membrane materials with new properties, such as fouling resistance, high permeability, and photocatalytic activity [7; 8; 9; 10]. Additionally, incorporating photocatalytic nanoparticles with membranes makes nanotechnology photocatalysis much more viable as it prevents the catalyst nanoparticles from leaching, and the nanoparticles become easier to recycle and reuse [2]. In the construction of photocatalytic membranes, the choice of the photocatalyst is crucial and TiO\({}_{2}\) has emerged to be one of the most popular semiconductors for this application [11; 12; 13; 14; 15]. This is not surprising as TiO\({}_{2}\) is the most widely used photocatalyst [16; 17]. However, the large-scale application of TiO\({}_{2}\)-nanoparticles as a photocatalyst is hampered because it is a wide bandgap semiconductor, the nanoparticles are difficult to separate from the treated water, and that its quantum efficiency (which is directly proportional to charge separation) is low [17; 18; 19]. This work seeks to address these issues by integrating different ideas that have been shown to work into a novel, efficient and effective material. Here, we developed a membrane consisting of TiO\({}_{2}\) nanoparticles doped with CuO embedded onto graphitic carbon nitride (GCN) and cast onto cellulose acetate (CA) membrane. The configuration of the membrane was 1% CuO/TiO\({}_{2}\) and immobilized on graphitic carbon nitride at a ratio of 1:9 (1% CuO/TiO\({}_{2}\):GCN). The purpose of doping TiO\({}_{2}\) with CuO was to reduce the bandgap of TiO\({}_{2}\) while immobilizing CuO/TiO\({}_{2}\) onto graphitic carbon was to enhance charge separation thus increasing the quantum efficiency of the material. CuO was selected because of its narrow bandgap that ranges between 1.2 and 1.7 eV thus its presence will allow for the absorption of visible light, thus increasing the amount of light absorbed [19].