Cellulose acetate (CA) is a semisynthetic, biodegradable polymer. Due to its characteristics, CA has several applications, including water membranes, filament-forming matrices, biomedical nanocomposites, household tools, and photographic films. This review deals with topics related to the CA membranes, which are prepared using different techniques, such as the phase inversion technique. CA membranes are considered very important since they can be used as microfiltration membranes (MF), ultrafiltration membranes (UF), nanofiltration membranes (NF), reverse osmosis (RO) membranes, and forward osmosis (FO) membranes. Membrane fouling results from the accumulation of materials that the membrane rejects on the surface or in the membrane’s pores, lowering the membrane’s flux and rejection rates. There are various forms of CA membrane fouling, for instance, organic, inorganic, particulate fouling, and biofouling. In this review, strategies used for CA membrane antifouling are discussed and summarized into four main techniques: feed solution pretreatment, cleaning of the membrane surface, membrane surface modification, which can be applied using either nanoparticles, polymer reactions, surface grafting, or surface topography, and surface coating.

The effects of functionalization of carbon nanotubes on the properties of nanocomposite sheets prepared from high-density polyethylene (HDPE) and carbon nanotubes (CNTs) were investigated. Carbon nanotubes were first oxidized, followed by amine group functionalization. The Fourier transform-infrared (FTIR) spectroscopy results confirm the presence of oxygenated and amide groups at the surface of the CNTs after each treatment. The HDPE/CNT nanocomposites sheets were prepared using a melt compounding method. Six types of CNTs were used; pristine Single-walled Carbon nanotubes (SWCNT) and pristine Multi-walled Carbon nanotubes (MWCNT), oxidized (O-SWCNT and O-MWCNT) and amide (Amide-SWCNT and Amide-MWCNT). All prepared nanocomposite sheets were characterized using Thermal gravimetric analysis (TGA), Differential scanning calorimetry (DSC), X-ray diffraction (XRD) and scanning electronic microscope (SEM). TGA results measured increased thermal stability of the polymer with the addition of CNTs, O-MWCNT showed the best enhancement. XRD measurements confirmed that the addition of CNTs did not change the crystal structure of the polymer, although the crystallinity was decreased. The maximum crystallinity decrease resulted from O-SWNTs addition to the polymer matrix. SEM imaging showed that oxidized and functionalized CNTs have more even dispersion in the polymer matrix compared with pristine CNTs.

Many techniques are used for the treatment of wastewater, including physical, chemical, biological, physiochemical, and biophysical methods. Advanced oxidation processes (AOPs), a chemical approach, are a key procedure for wastewater treatment. AOPs are applied to nonbiodegradable effluents, using less energy and chemicals while producing a completely biodegradable intermediate sample that can then undergo additional treatment to completely remove all organic matter. The AOPs can be chemical, photochemical, sonochemical, or electrochemical. Photochemical reactions accelerate the breaking down of organic pollutants using a photocatalyst that absorbs light and serves as a catalyst for chemical operations. There are a lot of photocatalysts that are used in water purification, such as TiO₂, ZnO, ZrO₂, CdS, CeO₂, ZnS, FeO, Fe₂O₃, SnO₂, and WO₃, and most of them are at the nanoscale. This article analyzes and covers the main aspects of using Fe₂O₃ nanoparticles for the purification of water and wastewater. It covers the application of Fe₂O₃ nanoparticles in the treatment of water and wastewater and the mechanisms of solar photodegradation of iron oxide (Fe₂O₃) photocatalysts. It shows the Fe₂O₃ nanoparticle synthesis methods and introduces the advantages and disadvantages of each technique. The review makes comparisons between the photocatalytic membrane reactor and the suspended system, as well as upcoming challenges and opportunities related to using Fe₂O₃ nanoparticles in these processes. This provides researchers with a different perspective on the photocatalysis outcomes that might be attained when the Fe₂O₃ photocatalysts are incorporated into various treatment systems.

Polyvinylidene fluoride (PVDF) membranes have become a favored choice for membrane filtration because of their outstanding mechanical characteristics, chemical resistance, thermal stability, and ease of handling. Nevertheless, the hydrophobic nature of PVDF membranes can result in fouling, which diminishes their efficiency over time. This study explores the impact of ZnO-Nanoclay on the properties and performance of mixed matrix membranes made from polyvinylidene fluoride (PVDF) at different loading percentages (0, 1, and 3 wt%). The ZnO-Nanoclay nanoparticles were synthesized using environmentally friendly methods, characterized, and blended into PVDF matrices via a solution-casting technique, resulting in a series of membranes. The synthesized nanoparticles were analyzed using Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD). The resulting mixed-matrix membranes underwent comprehensive analyses to assess their structure and surface properties, employing SEM, XRD, Atomic Force Microscopy (AFM), and contact-angle measurements. Furthermore, tensile, antibacterial, and barrier properties were evaluated. Integrating ZnO-Nanoclay into PVDF membranes greatly improves antifouling properties, achieving inhibition rates of 99.92% at a clay-loading percentage of 3 wt% and increasing water-flux rates by 16% compared to pure PVDF membranes at 1 wt%. In addition, ZnO-Nanoclay nanoparticles significantly boost the mechanical properties of PVDF membranes, enhancing maximum strength by 500% at 3 wt% loading. This study examines the interplay between the structure, properties, and performance of mixed-matrix membranes by comparing different PVDF membranes that were mixed with different nanoclay composites, providing significant insights into improving these membranes through the incorporation of nanoclay composites to enhance their overall properties and effectiveness.

Fe_2−xCu_xZr_2−xW_xO₇ (x: 0, 0.05, 0.015) nanoparticles were synthesized following the Pechini method and characterized via X-ray diffraction (XRD), transmission electron microscopy (TEM), and diffuse reflectance spectroscopy (DRS) measurements to be used as photocatalysts in colored water remediation. All of the prepared materials were crystallized in a cubic fluorite phase as the major phase. The band gap was reduced upon doping with W⁶⁺ and Cu²⁺ from 1.96 eV to 1.47 eV for Fe_1.85Cu₀.₁₅Zr_1.85W_0.15O₇. Carbol fuchsin (CF) dye was used to determine the photocatalytic degradation efficiency of the prepared catalysts. Degradation efficiency was directly proportional to the dopant’s concentration. Complete removal of 20 mg/L CF was achieved under optimal conditions (pH 9, and catalyst loading of 1.5 g/L) using Fe_1.85Cu_0.15Zr_1.85W_0.15O₇. The degradation rate followed pseudo-first-order kinetics. The reusability for photocatalysts was tested five times, decreasing its efficiency by 4% after the fifth cycle, which indicates that the prepared Fe_1.85Cu_0.15Zr_1.85W_0.15O₇ photocatalyst is a promising novel photocatalyst due to its superior efficiency in dye photodegradation.

A new nanophotocatalysts series of M₂Zr₂O₇ (M = Mn, Cu, and Fe) and doped Fe₂Zr₂O₇ systems were prepared via sol-gel using the pechini method, characterized, and tested in photocatalytic degradation of olive mill wastewater (OMW). The photocatalytic degradation of the prepared materials was evaluated by measuring total phenolic compounds (TPCs) using the Folin-Ciocalteu method for variable pH under a commercial LED lamp (45 W). The removal of TPCs was measured at different contact times ranging from 2 h to 6 days. X-ray diffraction (XRD) and transmission electron microscope (TEM) analysis approved the nano size of (5–17 nm) and quasi-spherical morphology of the prepared materials. ICP-OES analysis confirmed the XRD analysis and approved the structure of the prepared materials. Aggregation of the nanomaterials was observed using TEM imaging. Brunauer-Emmett-Teller (BET) analysis measured a 67 m²/g surface area for Fe₂Zr₂O₇. Doping Fe with Mn increased the surface area to 173 m²/g and increased to 187 m²/g with a further increase of the Mn dopant. Increasing the Mn dopant concentration increased both surface area and photocatalytic degradation. The highest degradation of TPCs was observed for Mn₂Zr₂O₇ around 70% at pH 10 and exposure time up to one day.