Dual-channel membrane capacitive deionization based on asymmetric ion adsorption for continuous water desalination

A Comparison of Capacitive Deionization and Membrane Capacitive Deionization Using Novel Fabricated Ion Exchange Membranes

Another technique for desalination, known as membrane capacitive deionization (MCDI), has been investigated as an alternative. This approach has the potential to lower the voltage that is required, in addition to improving the ability to renew the electrodes. In this study, the desalination effectiveness of capacitive deionization (CDI) was compared to that of MCDI, employing newly produced cellulose acetate ion exchange membranes (IEMs), which were utilized for the very first time in MCDI. As expected, the salt adsorption and charge efficiency of MCDI were shown to be higher than those of CDI. Despite this, the unique electrosorption behavior of the former reveals that ion transport via the IEMs is a crucial rate-controlling step in the desalination process. We monitored the concentration of salt in the CDI and MCDI effluent streams, but we also evaluated the pH of the effluent stream in each of these systems and investigated the factors that may have caused these shifts. The significant change in pH that takes place during one adsorption and desorption cycle in CDI (pH range: 2.3-11.6) may cause problems in feed water that already contains components that are prone to scaling. In the case of MCDI, the fall in pH was only slightly more noticeable. Based on these findings, it appears that CDI and MCDI are promising new desalination techniques that has the potential to be more ecologically friendly and efficient than conventional methods of desalination. MCDI has some advantages over CDI in its higher salt removal efficiency, faster regeneration, and longer lifetime, but it is also more expensive and complex. The best choice for a particular application will depend on the specific requirements.

Biotechnological advancements towards water, food and medical healthcare: A review

The global health status is highly affected by the growing pace of urbanization, new lifestyles, climate changes, and resource exploitation. Modern technologies pave a promising way to deal with severe concerns toward sustainable development. Herein, we provided a comprehensive review of some popular biotechnological advancements regarding the progress achieved in water, food, and medicine, as the most substantial fields related to public health. The emergence of novel organic/inorganic materials has brought about significant improvement in conventional water treatment techniques, anti-fouling approaches, anti-microbial agents, food processing, biosensors, drug delivery systems, and implants. Particularly, a growing interest has been devoted to nanomaterials and their application for developing novel structures or improving the characteristics of standard components. Also, bioinspired materials have been widely used to improve the performance, efficiency, accuracy, stability, safety, and cost-effectiveness of traditional systems. On the other side, the fabrication of innovative devices for precisely monitoring and managing various ecosystem and human health issues is of great importance. Above all, exceptional advancements in designing ion-selective electrodes (ISEs), microelectromechanical systems (MEMs), and implantable medical devices have altered the future landscape of environmental and biomedical research. This review paper aimed to shed light on the wide-ranging materials and devices that have been developed for health applications and mainly focused on the impact of nanotechnology in this field.

Mechanical Behavior of Crushed Waste Glass as Replacement of Aggregates

In this study, ground glass powder and crushed waste glass were used to replace coarse and fine aggregates. Within the scope of the study, fine aggregate (FA) and coarse aggregate (CA) were changed separately with proportions of 10%, 20%, 40%, and 50%. According to the mechanical test, including compression, splitting tensile, and flexural tests, the waste glass powder creates a better pozzolanic effect and increases the strength, while the glass particles tend to decrease the strength when they are swapped with aggregates. As observed in the splitting tensile test, noteworthy progress in the tensile strength of the concrete was achieved by 14%, while the waste glass used as a fractional replacement for the fine aggregate. In samples where glass particles were swapped with CA, the tensile strength tended to decrease. It was noticed that with the adding of waste glass at 10%, 20%, 40%, and 50% of FA swapped, the increase in flexural strength was 3.2%, 6.3%, 11.1%, and 4.8%, respectively, in amount to the reference one (6.3 MPa). Scanning electron microscope (SEM) analysis consequences also confirm the strength consequences obtained from the experimental study. While it is seen that glass powder provides better bonding with cement with its pozzolanic effect and this has a positive effect on strength consequences, it is seen that voids are formed in the samples where large glass pieces are swapped with aggregate and this affects the strength negatively. Furthermore, simple equations using existing data in the literature and the consequences obtained from the current study were also developed to predict mechanical properties of the concrete with recycled glass for practical applications. Based on findings obtained from our study, 20% replacement for FA and CA with waste glass is recommended.

Improvements in desorption rate and electrode stability of membrane capacitive deionization systems by optimizing operation parameters

The operating parameters necessary to improve the desorption rate of a membrane capacitive deionization (MCDI) system while controlling the Faradaic reactions were studied. The total charge (Q_T) accumulated in the carbon electrode was set as the main operating parameter determining the desorption rate of the MCDI system. After adsorption was performed until the preset Q_T value was reached using the MCDI unit cell, desorption was performed at a cell potential of -0.2 V. As a result of this MCDI operation, the average desorption rate increased in proportion to the Q_T value. Additionally, the ratio of desorption charge according to the desorption time was consistent regardless of Q_T. Through this, it could be seen that the desorption process of the MCDI system is similar to the discharge characteristic of a series circuit comprising a resistor (R) and a capacitor (C). If the desorption time is too short during the MCDI operation, some charges will remain in the carbon electrode. When the adsorption charge (Q_ad) is supplied again, Q_T increases. When Q_T exceeds the maximum allowable charge (MAC), which is the total charge at the onset of Faradaic reactions, electrode reactions can occur. Through RC circuit analysis, a model equation for calculating the minimum desorption time required to operate a MCDI system without the occurrence of Faradaic reactions was derived. As a result of MCDI operation while changing the desorption time, the desalination performance almost matched the result predicted through the model equation. Additionally, it was found that the smaller Q_ad is, the shorter the desorption time, resulting in a higher desalination rate of the MCDI system.

Novel application of ion exchange membranes for preparing effective silver and copper based antibacterial membranes

Ion exchange membranes (IEMs) are widely used in water treatment applications such as electrodialysis. However, the exploration of IEMs as effective antibacterial food contact materials (e.g., food packaging membranes) against pathogenic bacteria to ensure food safety has not been reported. Here, we report a simple but effective method to prepare high performance antibacterial membranes via ion exchange coupled with in-situ reduction. The general membrane properties are characterized using SEM, EDS, FTIR, XPS, XRD, DSC, TGA, water uptake, etc. The distribution of silver and copper in the membranes are generally in line with the distribution of sulfur, indicating that the antibacterial ions are introduced into the membranes via ion exchange and are bonded with the sulfonate groups in the membranes. The antibacterial performance is investigated using zone of inhibition tests and continuous bacteria growth inhibition tests. All of the prepared membranes show obvious antibacterial activities compared to the bare cation exchange membranes. The diameters of inhibition zone against Staphylococcus aureus (S. aureus) are all larger than those of Escherichia coli (E. coli), indicating that the prepared membranes are more efficient in inhibiting S. aureus compared to E. coli. Furthermore, the silver-based membrane shows more sustainable antibacterial activities compared to the copper-based membrane. Especially, the results clearly reveal that the silver-based membrane is capable of killing bacteria instead of just inhibiting the growth of bacteria. We have shown for the first time that membranes derived from IEMs have the potential as food contact materials to inhibit the growth of pathogenic bacteria so as to eliminate the risk of bacterial infections and meanwhile delay food spoilage due to bacteria growth.

Platinum complexation with glutamate amino acid: Computational study

In this research work, complex formation of platinum (Pt) metal particle with the glutamate (Glu) amino acid was investigated by performing density functional theory (DFT) calculations. Such application could be very much important regarding the importance of developing metal based biosensors for biological media. To achieve the purpose of this work, two spin numbers of 0 and 1 were considered for Pt for locating separately towards neutral and anionic forms of Glu for Pt / Glu complexes formations. The obtained results of optimization and QTAIM analyses indicated various configurations for different spin numbers of Pt metal particle towards each of neutral and anionic forms of Glu. Existence of covalent bond was observed for most cases in addition to existence of weak van der Waals interactions for the complexes.

CO and NO selective adsorption by a C16Mg8O8 nanocage: A DFT Study

Density functional theory (DFT) calculations were performed to stabilize a representative C16Mg8O8 nanocage derived from C32 and Mg16O16 counterparts for selective adsorption of carbon monoxide (CO) and nitrogen monoxide (NO) gaseous molecules. After obtaining optimized structures, molecular features were evaluated for describing the model systems. Diagrams of density of states (DOS) revealed that the energy differences between frontier molecular orbital levels of the highest occupied and the lowest unoccupied molecular orbitals (HOMO and LUMO) of the stabilized C16Mg8O8 nanocage could provide a more proper semiconductor in comparison with each of the original C32 and Mg16O16 cages. To explore the advantage of such C16Mg8O8 nanocage for CO and NO gases adsorption, molecular descriptors such as energies, geometries, and electronic structures were characterized for all possible adsorption configurations of bimolecular formation of gas . . .  nanocage. Significant changes of HOMO and LUMO levels besides the values of corresponding energy gaps of C16Mg8O8 nanocage in singular and bimolecular systems could help to recognize adsorption of each of CO and NO gaseous molecules. Furthermore, more variations of energy gaps in the process of gas . . .  nanocage bimolecular formation could lead to more sensitivity of nanocage for detection of adsorbed gases. As a consequence, the investigated C16Mg8O8 nanocage was introduced for differential recognition of CO and NO gases regarding several environmental health issues.

Substitution effects via aromaticity, polarizability, APT, AIM, IR analysis, and hydrogen adsorption in C20-nTin nanostructures: a DFT survey

In this paper, the substitution effects of titanium heteroatom(s) on aromaticity, the average isotropic polarizability (< α >), the atomic polar tensor (APT) charge, the electrostatic potential (ESP) map, and the atoms in molecule (AIM) analysis along with infrared (IR) spectroscopy of C₂₀ fullerene and its C_20-nTi_n derivatives (n = 1-5) are probed via density functional theory (DFT). The nucleus-independent chemical shifts (NICS) specify that substitution effect causes more aromaticity character of the optimized heterofullerenes than benzene molecule and higher APT charge distribution upon surfaces of them than pure cage. The highest negative and positive APT charge distribution on carbons of C₁₅Ti₅ and titanium substitutions of C₁₆Ti_4-2 implies that these sites can be attacked more readily by electrophilic and nucleophilic regents, respectively. We are very pleased to state that isolating the Ti-Ti single bonds by intermediacy of one or two C atoms is an applicable strategy for attaining the highest APT charge distribution on Ti atoms of C₁₆Ti_4-2 as suitable hydrogen storage. AIM analysis of the studied C_20-nAl_n derivatives signifies the highest electron density (ρ (r)) of 0.294 a.u. and the highest positive Laplacian of electron density (∇²ρ (r)) of 0.190 a.u., at bond critical points (BCPs) of C-Ti bond in the most stable C₁₉Ti₁ species. This heterofullerene shows the lowest < α > between the studied structures. IR spectroscopy shows that exclusive of C₁₆Ti_4-1 (as transition state), the other optimized hollow cages (as global minima) have no imaginary frequency.

Application of borophene as catechol sensor: a computational study

The efficacy of borophene (BP) as catechol (CC) sensor was explored using density functional theory (DFT) method. All calculations were performed at B3LYP level of theory and 6-31 + G(d) basis set employing the dispersion correction term of Grimme to consider dispersion interactions. The CC molecule is adsorbed on top of BP horizontally with the adsorption energy (E_ads) of about - 13.5 kcal·mol^-1. The HOMO and LUMO levels of nanosheet destabilize by about 0.36 and 0.14 eV, respectively, going from bare BP to BP-CC complex. Therefore, the E_g value decreases by about 10.5% upon adsorption process, which is a reasonable energy gap change for detection of CC. The negligible difference between the work function values (Φ, defined as the minimum amount of the energy needed to remove an electron from a solid to a point in the vacuum immediately outside the solid surface) of BP and its complex with CC indicates that the BP sheet is not an appropriate Φ-type sensor (in these sensors, adsorption of a chemical changes the gate voltage and produces an electrical signal that leads to the detection of chemical agent) for CC detection. The electrical conductivity of BP becomes 72 times higher after CC adsorption. The time needed for CC desorption from BP sheet is 7.6 ns, based on conventional transition state theory, showing that BP benefits from a short recovery time. The effect of CC concentration was explored by adsorption of 2 and 3 CC molecules on top of BP nanosheet and the results showed that the sensor response does not change by increasing the CC concentration. Also, the effect of lateral dimensions of BP on the adsorption energy was explored and it was shown that E_ads increases by enlargement of the nanosheet.

Predicting the Degree of Dissolved Oxygen Using Three Types of Multi-Layer Perceptron-Based Artificial Neural Networks

Predicting the level of dissolved oxygen (DO) is an important issue ensuring the sustainability of the inhabitants of a river. A prediction model can predict the DO level using a historical dataset with regard to water temperature, pH, and specific conductance for a given river. The model can be built using sophisticated computational procedures such as multi-layer perceptron-based artificial neural networks. Different types of networks can be constructed for this purpose. In this study, the authors constructed three networks, namely, multi-verse optimizer (MVO), black hole algorithm (BHA), and shuffled complex evolution (SCE). The networks were trained using the datasets collected from the Klamath River Station, Oregon, USA, for the period 2015–2018. We found that the trained networks could predict the DO level of 2019. We also found that both BHA- and SCE-based networks could predict the level of DO using a relatively simple configuration compared to that of MVO. From the viewpoints of absolute errors and Pearson’s correlation coefficient, MVO- and SCE-based networks performed better than BHA-based networks. In synopsis, the authors recommend MVO- and MLP-based artificial neural networks for predicting the DO level of a river.

Biosynthesis of spinel nickel ferrite nanowhiskers and their biomedical applications

Greener methods for the synthesis of various nanostructures with well-organized characteristics and biomedical applicability have demonstrated several advantages, including simplicity, low toxicity, cost-effectiveness, and eco-friendliness. Spinel nickel ferrite (NiFe2O4) nanowhiskers with rod-like structures were synthesized using a simple and green method; these nanostructures were evaluated by X-ray diffraction analysis, transmission electron microscopy, scanning electron microscopy, and X-ray energy diffraction spectroscopy. Additionally, the prepared nanowhiskers could significantly reduce the survival of Leishmania major promastigotes, at a concentration of 500 μg/mL; the survival of promastigotes was reduced to ≃ 26%. According to the results obtained from MTT test (in vitro), it can be proposed that further studies should be conducted to evaluate anti-leishmaniasis activity of these types of nanowhiskers in animal models.

Current Challenges and Advancements on the Management of Water Retreatment in Different Production Operations of Shale Reservoirs

Nowadays, water savings on industrial plants have become a significant concern for various plants and sections. It is vitally essential to propose applicable and efficient techniques to retreat produced water from onshore and offshore production units. This paper aimed to implement the PFF (Photo Fenton Flotation) method to optimize the water treatment procedure, as it is a two-stage separation technique. The measurements were recorded for the HF (hydraulic fracturing) and CEOR (chemically enhanced oil recovery) methods separately to compare the results appropriately. To assure the efficiency of this method, we first recorded the measurements for five sequential days. As a result, the total volume of 2372.5 MM m3/year of water can be saved in the HF process during the PFF treatment procedure, and only 20% of this required fresh water should be provided from other resources. On the other hand, the total volume of 7482.5 MM m3/year of water can be saved in CEOR processes during the PFF treatment procedure, and only 38% of this required fresh water should be provided from other resources. Therefore, the total water volume of 9855 MM m3 can be saved each year, indicating the efficiency of this method in supplying and saving the water volume during the production operations from oilfield units.

Reconfigurable and scalable 2,4-and 6-channel plasmonics demultiplexer utilizing symmetrical rectangular resonators containing silver nano-rod defects with FDTD method

Reconfigurable and scalable plasmonics demultiplexers have attracted increasing attention due to its potential applications in the nanophotonics. Therefore, here, a novel method to design compact plasmonic wavelength demultiplexers (DEMUXes) is proposed. The designed structures (two, four, and six-channel DEMUXes) consist of symmetrical rectangular resonators (RRs) incorporating metal nano-rod defects (NRDs). In the designed structures, the RRs are laterally coupled to metal-insulator-metal (MIM) waveguides. The wavelengths of the output channels depend on the numbers and radii of the metal NRDs in the RRs. The results obtained from various device geometries, with either a single or multiple output ports, are performed utilizing a single structure, showing real reconfigurability. The finite-difference time-domain (FDTD) method is used for the numerical investigation of the proposed structures. The metal and insulator used for the realization of the proposed DEMUXes are silver and air, respectively. The silver's permittivity is characterized by the well-known Drude model. The basic plasmonic filter which is used to design plasmonic DEMUXes is a single-mode filter. A single-mode filter is easier to cope with in circuits with higher complexity such as DEMUXes. Also, different structural parameters of the basic filter are swept and their effects on the filter's frequency response are presented, to provide a better physical insight. Taking into account the compact sizes of the proposed DEMUXes (considering the six-channel DEMUX), they can be used in integrated optical circuits for optical communication purposes.