## 3 Artificial Intervention in the Degradation of Antibiotics
### Physical Chemistry Methods
#### 3.3.2 Ultrafiltration Membrane Technology  
Generally speaking, membranes can be classified into two categories: low-pressure membranes, which include microfiltration and ultrafiltration membranes, and high-pressure membranes, which encompass nanofiltration and reverse osmosis membranes. This classification is based on the molecular weight of the retained substances and the pore size of the membranes. The pore size of ultrafiltration membranes ranges from 0.05 \(\upmu\)m to 1 nanometer, placing them between microfiltration membranes and nanofiltration membranes, and they are typically asymmetric membranes [99; 100]. They effectively retain colloids and large molecular substances, such as viruses, bacteria, and natural organic matter, based on the size of the contaminants, allowing small molecular substances to pass through the membrane layer [101]. In membrane separation technology, ultrafiltration membrane technology has been widely applied in various large-scale industrial applications and water treatment processes [102] due to (1) its ability to produce a high-quality effluent; (2) its cost-effectiveness in terms of capital costs and low-pressure operating costs, which makes it suitable for large-scale applications; and (3) its high potential for macromolecule removal, a lower footprint, and low energy consumption [103]. For example, in the treatment of pharmaceutical wastewater, ultrafiltration can be used as a pretreatment unit to remove macromolecular organic substances, such as proteins and polysaccharides, thereby reducing the pollution load on subsequent nanofiltration or reverse osmosis processes [104]. Despite the numerous advantages of ultrafiltration membrane technology, its application in large-scale water treatment still encounters challenges, such as membrane fouling and difficulties in managing concentrates. During operation, ultrafiltration membranes are susceptible to contamination from organic matter, colloids, and microorganisms, which adhere to the membrane surface during the filtration process, forming a cake layer or embedding within the membrane pores. This contamination leads to a reduction in the membrane's separation efficiency and results in membrane fouling. Therefore, to achieve a stable operation of the membrane separation technology and increase the efficiency of membrane materials, [PERSON] [105] prepared ultrafiltration membranes by physically blending graphene oxide (GO) with polyvinylidene fluoride (PVDF). Due to the numerous hydrophilic groups on the surface of GO, a hydrated layer forms on the hydrophilic surface, hindering the adsorption of hydrophobic contaminants, such as proteins, on the membrane surface. Additionally, GO, as a hydrophilic additive, accelerates the exchange rate between the coagulation bath (water/ethanol) and the solvent (DMAc), resulting in faster phase separation, the formation of a wider finger-like pore structure, and improvements in the surface charge effects and mechanical strength. These multiple factors work together to enhance the membrane's anti-fouling performance. In addition, [PERSON] [106] prepared a novel ultrafiltration membrane made of a polyvinylidene fluoride (PVDF) mixed matrix containing a reduced graphene oxide/titanium dioxide (rGO/TiO\({}_{2}\)) nanocomposite using a phase transformation method. Due to the high hydrophilicity of the rGO/TiO\({}_{2}\) nanocomposite, the rGO/TiO\({}_{2}\)/PVDF membrane is more hydrophilic than the bare PVDF membrane, and the pure water flux increased by 54.9%. The membrane's anti-fouling performance and flux recovery rate were significantly improved, with the best anti-fouling capability observed at a loading of 0.05 wt% rGO/TiO\({}_{2}\). In addition, the ultrafiltration process produces a concentrated solution with a high concentration of antibiotics, which may cause secondary pollution if discharged directly. [PERSON] et al.