Cellulose Acetate/Activated Carbon Composite Membrane with Effective Dye Adsorption Performance

Insights into the mechanically resilient, well-balanced polymeric membranes by incorporating Rhizophora mucronata derived activated carbon for sustainable wastewater decontamination

In this study, hydrophilic activated carbon has been prepared and used to synthesize innovative activated carbon/polysulfone mixed matrix membranes (MMMs). These membranes were investigated in terms of membrane morphology, hydrophilicity, antifouling ability, and metal ions rejection. The activated carbon (AC) was prepared from a simple chemical activation method using Rhizophora mucronata propagules, which are rich in aerenchyma cells and possess a high surface area. The hydrophilicity of the MMMs is enhanced by the incorporation of activated carbon, which is confirmed by the measurement of equilibrium water contact angle, water uptake and pure water flux. The optimized concentration of 0.625 wt% activated carbon (A₂) incorporated mixed matrix membrane exhibits better rejection efficiencies of 98 ± 0.5%, 99 ± 0.5%, 92 ± 2%, and 44 ± 1% for Pb⁺², Cd⁺², Hg⁺², and F^- with the permeate flux of 28.27, 31.88, 33.21, 43.82 L/m²/h, respectively. The fabricated mixed matrix membranes demonstrated an excellent flux recovery ratio and reversible fouling, when filtrating a mixed feed solution containing 200 ppm BSA, 10 ppm Pb⁺² and 10 ppm Cd⁺². The optimized A₂ membrane showed excellent long-term stability up to 120 h without compromising in permeate flux and rejection efficiency. Finally, a numerical investigation using a usual transport model has shown that dielectric exclusion was the most probable mechanism that can physically explain experimental trends.

Cellulose acetate in fabrication of polymeric membranes: A review

Developing biodegradable polymers to fabricate filtration membranes is one of the main challenges of membrane science and technology. Cellulose acetate (CA) membranes, due to their excellent film-forming property, high chemical and mechanical stability, high hydrophilicity, eco-friendly, and suitable cost, are extensively used in water and wastewater treatment, gas separation, and energy generation purposes. The CA is one of the first materials used to fabricate filtration membranes. However, in the last decade, the possibility of modification of CA to improve permeability and stability has attracted the researcher's attention again. This review is focused on the properties of cellulose derivatives and especially CA membranes in the fabrication of polymeric separation membranes in various applications such as filtration, gas separation, adsorption, and ion exchange membranes. Firstly, a brief introduction of CA properties and used molecular weights in the fabrication of membranes will be presented. After that, different configurations of CA membranes will be outlined, and the performance of CA membranes in several applications and configurations as the main polymer and as an additive in the fabrication of other polymer-based membranes will be discussed.

Recycling of Waste Cotton Sheets into Three-Dimensional Biodegradable Carriers for Removal of Methylene Blue

Waste cotton sheets (WCS) are promising cellulose sources due to their high content of cellulose and large amount of disposal every year, which could be recycled and employed as low-cost structural materials. The present work aims at investigating the efficacy of hydrogel adsorbents prepared from regenerated WCS as the carriers of activated carbon (AC) for treating the dye-contaminated water. Activated WCS was directly dissolved in lithium chloride/N,N-dimethylacetamide (LiCl/DMAc) solvent and then regenerated into cellulose hydrogels, which were employed as three-dimensional biodegradable matrices for loading an extremely high content of AC (up to 5000%). The morphology and properties of resultant adsorbents were studied in detail. The results showed that different washing methods and contents of AC and cellulose had obvious effects on water contents, mechanical properties, and adsorption capacities of AC/WCS hydrogels. Especially, the hydrogels containing high AC content washed by gradient ethanol solvent exhibited outstanding compressive strengths of up to 3.0 MPa at 60% strain, while the adsorption capacity of 5000%AC/0.3CS toward a model dye methylene blue (MB, initial concentration of 200 mg/L) reached 174.71 mg/g at pH 6.9 and 35 °C. This was comparable to the adsorption capacity of original AC powders, while no AC powders were released from hydrogels to water. The adsorption of MB followed the Dubinin-Astakhov model and pseudo-first-order mechanism. Thermodynamic studies showed the spontaneous and endothermic nature of the overall physical adsorption process. Therefore, this work demonstrates the feasibility to recycle WCS into biodegradable carriers of functional compounds, and the AC/regenerated cellulose hydrogels have a high potential as a promising adsorbent with low-cost and convenient separation for dye removal from wastewater.

One-Step Synthesis of Eu3+-Modified Cellulose Acetate Film and Light Conversion Mechanism

A CA-Eu(III) complex was synthesized by the coordination reaction of cellulose acetate (CA) and Eu³⁺ to obtain a CA-Eu light conversion film. This product was then doped with Tb(III) to sensitize the luminescence of Eu³⁺, which could functionalize the CA film. FTIR and XPS showed that the oxygen atoms in C=O, C-O (O=C-O), and O-H were involved in the complexation with Eu³⁺ and formed a Eu-O bond. SEM revealed that Eu³⁺ filled in the pores of the CA film. By changing the experimental conditions, the best fluorescence performance was obtained at the CA: Eu³⁺ ratio of 3:1 with a reaction time of 65 min. The energy transfer between Tb³⁺-Eu³⁺ could be realized by doping Tb³⁺ to enhance the luminescence of Eu³⁺. The best fluorescence performance of the CA-Eu-Tb light conversion film was at a Eu³⁺:Tb³⁺ ratio of 3:1. Compared with the CA film, the light conversion film has high transparency, high tensile strength, and good flexibility. It can convert the ultraviolet light harmful to plants into red light that is beneficial to photosynthesis. This offers high efficiency and environmental protection in the field of agricultural films.