Search Results (26)

Recycling water offers a powerful way to lower the environmental water impact of mining activities. Pressure-retarded osmosis (PRO) represents a promising pathway for simultaneous water reuse and clean energy generation from salinity gradients. In this study, the performance of a thin-film nanocomposite (TFN) membrane containing functionalized multi-walled carbon nanotubes (fMWCNTs) within a polyacrylonitrile (PAN) support layer, followed by polydopamine (PDA) surface modification, was investigated under a PRO operation using pretreated gold mining wastewater as the feed solution. Unlike most previous studies that rely on synthetic feeds, this work evaluates the membrane performance under a PRO operation using a real mining wastewater stream. The membrane with fMWCNTs and PDA exhibited a maximum power density of 25.22 W/m² at 12 bar, representing performance improvements of 23% and 68% compared with the pristine thin-film composite (TFC) and commercial cellulose triacetate (CTA) membranes, respectively. A high water flux of 75.6 L·m⁻²·h⁻¹ was also obtained, attributed to enhanced membrane hydrophilicity and reduced internal concentration polarization. The optimized membrane, containing 0.3 wt% fMWCNTs in the support layer and a PDA coating on the active layer, produced a synergistic enhancement in the PRO performance, resulting in a lower reverse salt flux and an improved flux–selectivity trade-off. Furthermore, the ultrafiltration (UF) and nanofiltration (NF) pretreatment effectively reduced the hardness and ionic content, enabling a stable PRO operation with real mining wastewater over a longer period of time. Overall, this study demonstrates the feasibility of achieving both reusable water and enhanced osmotic power generation using modified TFN membranes under realistic mining wastewater conditions. Full article

This paper presents a novel batch Forward Osmosis (FO) process for hydropower generation. It focuses on analyzing the parameters needed to make the proposed osmotic power plant implementable with currently available technology. Starting from the solution–diffusion model and using flow and mass balance equations, the equations that describe the behavior of the system over time are obtained. Membrane orientation, concentration polarization, reverse solute flux, and membrane fouling are not considered. The equations for calculating the operation time for the charging and discharging stages are obtained. Also, an equation for calculating the required membrane area to make the duration of the two stages the same is obtained. The results indicate that a volume of approximately $30.4 {\mathrm{m}}^3$ discharging through a $0.84 \mathrm{i}\mathrm{n}\mathrm{c}\mathrm{h}$ diameter outflow jet towards a turbine could generate an energy of $25 \mathrm{k}\mathrm{w}·\mathrm{h}.$ The discharging stage would take $12 \mathrm{h}$, and with a membrane with a water permeability constant $A_m=1.763·{10}^{-12} \mathrm{m}/(\mathrm{s}·\mathrm{P}\mathrm{a})$, the charging stage would require a membrane superficial area ${Ar}_m=1·{10}^4 {\mathrm{m}}^2$ to have the same duration. The proposed osmotic power plant, whose working principle is based on volume change over time, contrary to pressure retarded osmosis, whose working principle requires expending energy to extract energy from the salinity gradient, could deliver greater net produced energy with comparatively lower operational costs as it does not require high-pressure pumps or energy recovery devices as are required in pressure-retarded osmosis. The use of several tanks that charge and discharge alternatively can make the system generate energy as if it were a continuous process. Full article

Membrane innovations have become a key solution for overcoming the bottlenecks in efficiency upgrade in many green energy fields. Membrane performance depends on two key parameters permeability and selectivity, which typically follow a trade-off relationship: improving one often diminishes the other. Two-dimensional (2D) materials, which have atomic-level thickness, tunable pore sizes, and reasonable functionalization, offer great promises to break through the trade-off effect and redesign high-efficiency mass transfer pathways. This review systematically presents recent efforts in both preparation and potential applications of 2D materials for overcoming the permeability–selectivity trade-off. It highlights four prevailing fabrication strategies: chemical vapor deposition, interfacial synthesis, solution-phase synthesis, and exfoliation, and shows some major optimization techniques for various 2D materials. Additionally, this review discusses emerging applications of 2D materials across critical fields from water treatment (seawater desalination, metal ion extraction) to energy technologies (osmotic power generation, direct methanol fuel cells, and vanadium redox flow batteries). Finally, the challenges and future prospects of 2D materials in ion separation and energy conversion are discussed. Full article

The electrodynamics of current provide much of our technology, from telegraphs to the wired infrastructure powering the circuits of our electronic technology. Current flow is analyzed by its own rules that involve the Maxwell Ampere law and magnetism. Electrostatics does not involve magnetism, and so current flow and electrodynamics cannot be derived from electrostatics. Practical considerations also prevent current flow from being analyzed one charge at a time. There are too many charges, and far too many interactions to allow computation. Current flow is essential in biology. Currents are carried by electrons in mitochondria in an electron transport chain. Currents are carried by ions in nerve and muscle cells. Currents everywhere follow the rules of current flow: Kirchhoff’s current law and its generalizations. The importance of electron and proton flows in generating ATP was discovered long ago but they were not analyzed as electrical currents. The flow of protons and transport of electrons form circuits that must be analyzed by Kirchhoff’s law. A chemiosmotic theory that ignores the laws of current flow is incorrect physics. Circuit analysis is easily applied to short systems like mitochondria that have just one internal electrical potential in the form of the Hodgkin Huxley Katz (HHK) equation. The HHK equation combined with classical descriptions of chemical reactions forms a computable model of cytochrome c oxidase, part of the electron transport chain. The proton motive force is included as just one of the components of the total electrochemical potential. Circuit analysis includes its role just as it includes the role of any other ionic current. Current laws are now needed to analyze the flow of electrons and protons, as they generate ATP in mitochondria and chloroplasts. Chemiosmotic theory must be replaced by an electro-osmotic theory of ATP production that conforms to the Maxwell Ampere equation of electrodynamics while including proton movement and the proton motive force. Full article

During clathrin-mediated endocytosis in yeast cells, a small patch of flat membrane is deformed into a tubular shape. It is generally believed that the tubulation is powered by actin polymerization. However, studies based on quantitative measurement of the actin molecules suggest that they are not sufficient to produce the forces to overcome the high turgor pressure inside of the cell. In this paper, we model the membrane as a viscous 2D fluid with elasticity and study the dynamic membrane deformation powered by a boundary lipid flow under osmotic pressure. We find that in the absence pressure, the lipid flow drives the membrane into a spherical shape or a parachute shape. The shapes over time exhibit self-similarity. The presence of pressure transforms the membrane into a tubular shape that elongates almost linearly with time and the self-similarity between shapes at different times is lost. Furthermore, the width of the tube is found to scale inversely to the cubic root of the pressure, and the tension across the membrane is negative and scales to the cubic root squared of the pressure. Our results demonstrate that boundary flow powered by myosin motors, as a new way to deform the membrane, could be a supplementary mechanism to actin polymerization to drive endocytosis in yeast cells. Full article

Graphene is a revolutionary material with excellent optical, electrical and mechanical properties and has garnered significant attention in the realm of nanopore technology. Devices incorporating graphene nanopores leverage the material’s atomic thickness to enhance detection precision in solid-state nanopores. These nanopores exhibit high spatial resolution and ion selectivity, making them promising sensors for biomolecular detection. Additionally, their unique characteristics suggest their considerable potential for applications in material separation and osmotic power generation. In recent years, several literature reviews on graphene nanopores have been published; however, some have not fully addressed certain important aspects, such as the depth of theoretical analysis, the extent of coverage on technological advancements, and the exploration of potential applications. This paper reviews current fabrication methods, including “top-down” etching and “bottom-up” synthesis, highlighting their advantages and limitations. We also summarize diverse applications of graphene nanopores, such as in biomolecule detection and water desalination. Our findings emphasize the need for a deeper exploration of these aspects, advancing the field by showcasing the broader potential of graphene nanopores in addressing various technological challenges. Full article

Natural environment hosts a considerable amount of accessible energy, comprising mechanical, thermal, and chemical potentials. Environment-induced nanogenerators are nanomaterial-based electronic chips that capture environmental energy and convert it into electricity in an environmentally friendly way. Polymers, characterized by their superior flexibility, lightweight, and ease of processing, are considered viable materials. In this paper, a thorough review and comparison of various polymer-based nanogenerators were provided, focusing on their power generation principles, key materials, power density and stability, and performance modulation methods. The latest developed nanogenerators mainly include triboelectric nanogenerators (TriboENG), piezoelectric nanogenerators (PENG), thermoelectric nanogenerators (ThermoENG), osmotic power nanogenerator (OPNG), and moist-electric generators (MENG). Potential practical applications of polymer-based nanogenerator were also summarized. The review found that polymer nanogenerators can harness a variety of energy sources, with the basic power generation mechanism centered on displacement/conduction currents induced by dipole/ion polarization, due to the non-uniform distribution of physical fields within the polymers. The performance enhancement should mainly start from strengthening the ion mobility and positive/negative ion separation in polymer materials. The development of ionic hydrogel and hydrogel matrix composites is promising for future nanogenerators and can also enable multi-energy collaborative power generation. In addition, enhancing the uneven distribution of temperature, concentration, and pressure induced by surrounding environment within polymer materials can also effectively improve output performance. Finally, the challenges faced by polymer-based nanogenerators and directions for future development were prospected. Full article

Recent studies have demonstrated dose-responses of the cannabis plant to supply of macronutrients. However, further development of precision nutrition requires a high-resolution understanding of temporal trends of plant requirements for nutrients throughout the developmental progression, which is currently not available. As plant function changes during development, temporal information on nutrient uptake should be considered in relation to gradients in developmental-related physiological activity. Therefore, the present study investigated tempo-developmental trends of nutritional demands in cannabis plants, and in relation to physiological performance. Three cultivars differing in phenotype and chemotype were analyzed to evaluate genotypic variability. The results demonstrate that nutrient acquisition and deposition rates change dramatically during plant development. Uptake of individual minerals generally increased with the progression of both vegetative and reproductive development and the increase in plant biomass, while the deposition rates into the plant demonstrated nutrient specificity. The average concentrations of N, P, and K in the shoots of the different cultivars were 2.33, 4.90, and 3.32 times higher, respectively, at the termination of the reproductive growth phase, compared to the termination of the vegetative growth phase. Surprisingly, the uptake of Ca was very limited during the second part of the reproductive growth phase for two cultivars, revealing a decrease in Ca demand at this late developmental stage. Root-to-shoot translocation of most nutrients, including P, K, Mg, Mn, and Zn, as well as Na, is higher during the reproductive than the vegetative growth phase, and Fe, Mn, Zn, Cu, and Na displayed very little root-to-shoot translocation. The physiological characteristics of the plants, including gas exchange parameters, membrane leakage, osmotic potential, and water use efficiency, changed over time between the vegetative and the reproductive phases and with plant maturation, demonstrating a plant-age effect. The revealed tempo-developmental changes in nutritional requirements of the cannabis plant are a powerful tool required for development of a nutritional protocol for an optimal ionome. Full article

Biomass-derived materials have traditionally been used to generate electrical energy through the combustion of their organic components. However, within the past few years, certain common biomass compounds, especially plant-based products such as cellulose and lignin, have drawn attention in the energy field due to their wide availability, low cost, and chemical versatility. In the case of cellulose, the combination of crystalline and amorphous domains, along with the high surface area and abundance of hydroxyl groups, has allowed for its application in multiple devices to harvest energy from the environment. However, to date, there are no reviews focusing on the different approaches that have been developed to implement these sustainable materials in the generation of renewable energies and the desirable material properties for these applications. This manuscript reviews alternative ways that have been developed to exploit biomass compounds in power generation, especially cellulose and lignin. Three different types of energy harvesting are discussed: mechanical, osmotic, and thermal energy. In the case of mechanical energy, the application of plant-derived materials in piezoelectric and triboelectric generators is described. In both cases, approaches where the biomass material has an active role in power generation instead of acting as a mechanical support are reported. For osmotic energy, the performance of inverse electrodialysis systems and the use of plant-derived materials, including the chemical modifications carried out to allow for their use for energy generation, was reviewed. Finally, for thermal energy generation, the reported work on biopolymer-based devices that work using thermoelectricity has been summarised. In each case, the latest advances in the field from the materials science perspective and the reported performance were described. Hybrid approaches involving the combination of biomass materials with other components have also been considered and compared with the performance obtained using biopolymers alone. Current limitations and opportunities are, finally, discussed to offer an overview of the current landscape and indicate future directions of the field. Full article

In recent years, the utilization of the selective ion transport through porous membranes for osmotic power generation (blue energy) has received a lot of attention. The principal of power generation using the porous membranes is same as that of conventional reverse electrodialysis (RED), but nonporous ion exchange membranes are conventionally used for RED. The ion transport mechanisms through the porous and nonporous membranes are considerably different. Unlike the conventional nonporous membranes, the ion transport through the porous membranes is largely dictated by the principles of nanofluidics. This owes to the fact that the osmotic power generation via selective ion transport through porous membranes is often referred to as nanofluidic reverse electrodialysis (NRED) or nanopore-based power generation (NPG). While RED using nonporous membranes has already been implemented on a pilot-plant scale, the progress of NRED/NPG has so far been limited in the development of small-scale, novel, porous membrane materials. The aim of this review is to provide an overview of the membrane design concepts of nanofluidic porous membranes for NPG/NRED. A brief description of material design concepts of conventional nonporous membranes for RED is provided as well. Full article

There are many promising renewable energy (RE) technologies that could help increase the contribution of RE in energy supply but which are not yet commercially available. The development rate of new RE technologies depends on many factors, such as Research and Development (R&D) efforts and policies. This study focuses on comparing China’s efforts regarding the development of new RE technologies (e.g., wave and tidal, binary geothermal power, floating solar, micro hydro, osmotic energy, floating offshore wind and vertical axis wind turbines) with those of the European Union (EU). For this purpose, we collected data from publications and databases and analysed several indicators: e.g., the development of renewable electricity generation and capacity, demonstration projects, investments in R&D and patent applications. The results show that China has become a big player globally for mainstream renewable electricity (hydropower, wind and solar PV). This development is due to China’s industrial policy and prioritization of effectiveness over cost efficiency. The main developments in China occurred in the 2010s, while the EU was a frontrunner in the 2000s. For the newer or less mainstream technologies, the application in China is still low, compared to the EU, except for floating solar, where China is a lead player. Regarding patent applications, China has shown a higher application amount compared to the EU since 2006. However, only a small share of China’s patents are valid internationally. We conclude that China has emerged as a big player in mainstream renewable energy technologies over the last decade. In regard to new renewable energy technologies, China is predominantly involved in solar energy and, in comparison to the EU, less in other new technologies (e.g., binary geothermal systems and ocean energy). Full article

Many geothermal plants have been shut down due to reinjection problems with the heat-depleted brine. In Denmark, only one out of three plants that extract heat from a geothermal fluid distributed to the district heating system is still working. In general, the large salinity of heat-depleted geothermal brines can be used to produce electricity with the help of turbines and generators through an osmotic power unit known as a SaltPower plant. Harnessing more energy out of the reinjection of geothermal brines is feasible without compromising the overall reservoir assurance when the iron is kept under control. This study is an attempt to determine the feasibility of the reinjection of a diluted geothermal brine with ethylenediaminetetraacetic acid (EDTA) into homogeneous and heterogeneous sandstone rocks. The results from the coreflooding experiments show an improvement in the rock properties both in porosity and permeability for homogeneous and heterogeneous rocks. EDTA not only avoids the precipitation of Fe(III) oxides inside the porous media but can also be used for scale removal and matrix acidizing in geothermal reservoirs. Full article

An investigation of the effect of the molecular weight of polyethylene glycol (PEG) on thin-film composite (TFC) flat sheet polysulfone membrane performance was conducted systematically, for application in forward osmosis (FO) and pressure retarded osmosis (PRO). The TFC flat sheet PSf-modified membranes were prepared via a non-solvent phase-separation technique by introducing PEGs of different molecular weights into the dope solution. The TFC flat sheet PSf-PEG membranes were characterized by SEM, FTIR and AFM. The PSf membrane modified with PEG 600 was found to have the optimum composition. Under FO mode, this modified membrane had a water permeability of 12.30 Lm⁻²h⁻¹ and a power density of 2.22 Wm⁻², under a pressure of 8 bar in PRO mode, using 1 M NaCl and deionized water as the draw and feed solutions, respectively. The high water permeability and good mechanical stability of the modified TFC flat sheet PSF-PEG membrane in this study suggests that this membrane has great potential in future osmotically powered generation systems. Full article

In this study, we propose a new approach to attain energy by salinity gradient engines with pistons based on hydrogels possessing polyelectrolyte and antipolyelectrolyte effects in a tandem arrangement, providing energy in each salinity gradient mode in a repeatable manner. The swelling of hydrogel with a polyelectrolyte effect and shrinking of hydrogel particles possessing an antipolyelectrolyte effect in desalinated water, and subsequent shrinking of hydrogel with polyelectrolyte and swelling of hydrogel antipolyelectrolyte effect in saline water, generate power in both increasing and decreasing salinity modes. To investigate the energy recovery, we scrutinized osmotic engine assemblies by a setup arrangement of pistons with hydrogel particles, with polyelectrolyte and antipolyelectrolyte effects, in tandem. The energy recovery from the tandem engine setup (calculated based on dry form for each polyelectrolyte polyacrylate-based hydrogel-SPA) and antipolyelectrolyte–sulfobetaine-based gel with methacrylate polymeric backbone-SBE) up to 581 J kg⁻¹ and a mean power of 0.16 W kg⁻¹ was obtained by the tandem setup of SPA and SBE hydrogel containing 3% crosslinking density and particle size of 500 microns with an external load of 3.0 kPa. Exchange of sulfobetaine with methacrylamide (SBAm), the main polymer backbone, revealed a positive increase in energy recovery of 670 J kg⁻¹ with a mean power of 0.19 W kg⁻¹ for the tandem system operating under the same parameters (SPA@SBAm). The energy recovery can be controlled, modulated and tuned by selecting both hydrogels with antipolyelectrolyte and polyelectrolyte effects and their performing parameters. This proof of concept provides blue energy harvesting by contributing both polyelectrolyte and antipolyelectrolyte effects in a single tandem setup; together with easy accessibility (diaper-based materials (SPA)) and known antibiofouling, these properties offer a robust alternative for energy harvesting. Full article

Harvesting salinity gradient energy, also known as “osmotic energy” or “blue energy”, generated from the free energy mixing of seawater and fresh river water provides a renewable and sustainable alternative for circumventing the recent upsurge in global energy consumption. The osmotic pressure resulting from mixing water streams with different salinities can be converted into electrical energy driven by a potential difference or ionic gradients. Reversed-electrodialysis (RED) has become more prominent among the conventional membrane-based separation methodologies due to its higher energy efficiency and lesser susceptibility to membrane fouling than pressure-retarded osmosis (PRO). However, the ion-exchange membranes used for RED systems often encounter limitations while adapting to a real-world system due to their limited pore sizes and internal resistance. The worldwide demand for clean energy production has reinvigorated the interest in salinity gradient energy conversion. In addition to the large energy conversion devices, the miniaturized devices used for powering a portable or wearable micro-device have attracted much attention. This review provides insights into developing miniaturized salinity gradient energy harvesting devices and recent advances in the membranes designed for optimized osmotic power extraction. Furthermore, we present various applications utilizing the salinity gradient energy conversion. Full article