Electrospinning and electrospraying are electrohydrodynamic processes used for the fabrication of nano- and microfiber membranes and the deposition of particles on the membrane. Despite the numerous research papers found in the literature on electrospun polymers and their application in water treatment, not much is reported on the functionalization of electrospun nano- or microfibers and the deposition of ceramic nanoparticles on their surface by electrospraying. The use of these two processes may increase the efficiency of membranes in removing contaminants. In the present research, the processes of electrospinning and electrospraying are described and the factors affecting electrospinning are investigated. All parameters affecting the production of smooth NFs and NPs are discussed. A literature review of the recent advances in electrospinning and electrospray applications, as well as the application of NFs membranes in water treatment, has been described. This research has been designed based on the knowledge gaps identified in the literature. Detailed experiments were carried out on the preparation of PAN_P and Cs_P NFs membranes by electrospinning technique, the NFs membranes were then functionalized with different functional groups. The membranes were used for removal (Chapter 3) and degradation (Chapters 4 and 5) of dyes synthetic solutions. In the case of degradation, the membranes were electrosprayed with TiO2 NPs. All membranes were characterized by standard spectroscopic, microscopic, surface analytical, and thermal methods. Adsorption of MB, RB, and ST from a synthetic aqueous solution on the membranes PAN and EA-g-PAN NFs decreased in the order PAN<EA-g-PAN. The adsorption isotherm for the dyes fitted well with the models of Langmuir and Freundlich. The values of the correlation coefficient (r2) for Langmuir varied from 0.940 to 0.995 and for Freundlich from 0.941 to 0.998. The slightly increased values of the correlation coefficient in the case of Freundlich indicate that condensation (physical adsorption) of dyes on the NFs membranes also occurred in addition to the formation of monolayers. PAN_P NFs membranes prepared by electrospinning were functionalized with DETA to produce a functionalized PAN _F NFs membrane. TiO2 NPs synthesized in the laboratory were anchored to the surface of the PAN_F NFs membrane by electrospray to prepare PAN _Coa. A second PAN_Co was prepared by embedding TiO2 NPs into the PAN_P NFs by electrospinning. A similar strategy was also used for the Cs and TiO2 NPs system. The PAN_Coa NFs membrane was used for the degradation of MO while the Cs_Coa NFs membrane was used for the degradation of MB. The higher photocatalytic activity of PAN _Coa NFs membranes (92%, 20 ppm, and 99.5%, 10 ppm) compared to PAN_Co NFs membranes (41.64%) was due to the smaller band gap, high surface roughness, and large surface area. Also, the higher photocatalytic activity of the Cs_Coa NFs membrane (89%) compared to TiO2/Cs composite (Cs_Co) NFs membranes (40%) was due to a balance between the band gap, high surface roughness, and lower surface area. BET showed that the isotherms and hysteresis were similar for all NFs membranes, and they were classified as isotherm type IV and hysteresis H3 (IUPAC), corresponding to mesopores and slit-shaped pores.