Abstract To ascertain membrane distillation (MD) as an emerging desalination technology to meet the global water challenge, development of membranes with ideal material properties is crucial. Functionalized carbon nanotubes (CNTs) were anchored to nanofibres of electrospun membranes. Covalent modification and fluorination of CNTs improved their dispersibility and interfacial interaction with the polymer membrane, resulting in well-aligned CNTs inside crystalline fibres with superhydrophobicity. Consideration for the chemical/physical properties of the CNT composite membranes and calculation of their theoretical fluxes revealed the mechanism of MD: CNTs facilitated the repulsive force for Knudsen and molecular diffusions, reduced the boundary-layer effect in viscous flow, and assisted surface diffusion, allowing for fast vapor transport with anti-wetting. This study shows that the role of CNTs and an optimal composite ratio can be used to reduce the gap between theoretical and experimental approaches to desalination.
Photothermal desalination is a promising approach for seawater purification by harvesting solar energy. Titanium carbide (Ti3C2Tx MXene) membranes have been regarded as potential materials for photothermal desalination by virtue of their excellent light-to-heat conversion. However, achieving a well-balanced synergy between high evaporation rate and good salt resistance remains a significant challenge due to their limited solar absorption and inferior stability. Herein, we report a self-assembled flexible porphyrin-Ti3C2Tx MXene Janus membrane (Janus PMX membrane) for dual-functional enabled photothermal desalination. The self-assembly of porphyrin on MXene not only effectively creates a favorable hydrophobic surface but also simultaneously enables efficient solar utilization. The significant interactions and charge redistribution between MXene and porphyrin lead to a stable hydrophobic/hydrophilic Janus structure with synergistically enhanced photothermal conversion. As a result, the Janus PMX membrane demonstrates highly efficient water pumping, heat localization, vapor generation, and salt resistance during photothermal desalination. This work presents an effective and facile strategy toward advancing a well-performing MXene membrane for efficient seawater desalination.
This study investigated the application of waste banana peels as feedstock for the production of ethanol fuel as a second-generation biofuel. First, acid pretreatment followed by enzymatic hydrolysis converted both the cellulosic and hemicellulosic biomass of the peels into fermentable sugars, which eventually produced ethanol by yeast fermentation. The optimal conditions for the production of ethanol fuel were determined by orthogonal experimental design method. The results showed that 100 g of fresh banana would produce 31.4 g of banana peel which could be turned into 2.8 g dried peel powder. Under optimal conditions of acid pretreatment with 0.2% tartaric acid, enzymatic hydrolysis by cellulase and yeast fermentation, 115 mg of ethanol (95% purity) could be recovered by distillation from the fermentation broth, which was approximately 4% by weight of the dried peel powder. This study concluded that banana fruit, after the removal of peels for consumption or food processing, the discarded peels will no longer pose an organic waste problem to the environment if they could be recollected and converted into value-added products like ethanol fuel. We also demonstrated that tartaric acid, an organic acid used in the acid pretreatment, for the first time to our knowledge, outperformed the traditional sulfuric acid used commonly in other studies.
Due to its tunable interlayer chemistry, MXene shows great potential in various sensors, however, the optoelectronic properties of MXene are greatly hindered by the slow photoresponse of the intercalation chemistry. In this work, Ti3C2TX monolayer and multilayer films are self-assembled so that the embedded H2O content can be controlled by tuning the stacked layers. Therefore, the photoelectric properties of Ti3C2TX are highly related to the film thickness, resulting in opposite changes in resistance under laser irradiation. In addition, monolayer films with few intercalators are more suitable for optoelectronic applications, and their resistance recovery is much faster than multilayer films. Furthermore, this work also helps explore the critical role of film thickness in the MXene-based optoelectronic sensors.
Development that satisfies the present requirements without sacrificing the needs of future generations is termed sustainable development. The idea of sustainable development is to maintain the balance among environment, society and economy for standards of quality of life both in present and future generations. In this chapter, an overview of various areas of sustainable development, mainly social equity, economic and environmental aspects, along with case studies are presented. Environmental indicators in sustainable development, sustainable buildings and construction, renewable and sustainable approaches for solid waste management, and water production are discussed in brief.
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