The drastic rise in global warming and the fossil fuel consumption have resulted in destruction of the ecological balance, reduction of the environmental quality, and demotion of the sustainable ...development. The utilization of biofuels have been paid much attention to by researchers and policy makers due to its benefits and indisputable contributions to protect the living environment. Free fatty acid-rich rice bran oil which is unsuitable for food purposes could be a good candidate for biofuel production. Accordingly, rice bran oil-based biofuels (straight oil and its biodiesel) as promising alternative fuels to petrodiesel were reviewed in this article from the sources, components, and physicochemical perspectives. In addition, biodiesel production from rice bran oil using various methods and catalysts was thoroughly detailed. The oxidative stability of rice bran biodiesel as a function of the storage time was also discussed. The application of rice bran oil-based biofuels to diesel engines was completely analyzed and critically discussed based on engine performance, combustion, and emissions characteristics. The effects of using rice bran oil-based biofuels on the lubricating oil degradation, deposit formation, wear, and sound intensity of diesel engines were explained in detail. Finally, the economic aspects of using rice bran oil and its biodiesel as fuels were also assessed. As a conclusion, the blend containing 20% rice bran oil biodiesel and 80% petrodiesel fuel, both in volume, could be the most effective composition considering the techno-economic aspects of diesel engines; meanwhile the remaining blends appeared to be improper for the existing diesel engines.
•Various aspects of biofuels from rice bran oil as alternatives to diesel are reviewed.•Biodiesel production from rice bran oil using various methods is analyzed in detail.•The effects of rice bran oil-based biofuels on the behavior of engines are detailed.•The economic aspects of using rice bran oil and its biodiesel as fuels are assessed.•Blending diesel with 20% rice bran oil biodiesel could lead to promising results.
Conventional water resources in many regions are insufficient to meet the water needs of growing populations, thus reuse is gaining acceptance as a method of water supply augmentation. Recent ...advancements in membrane technology have allowed for the reclamation of municipal wastewater for the production of drinking water, i.e., potable reuse. Although public perception can be a challenge, potable reuse is often the least energy-intensive method of providing additional drinking water to water stressed regions. A variety of membranes have been developed that can remove water contaminants ranging from particles and pathogens to dissolved organic compounds and salts. Typically, potable reuse treatment plants use polymeric membranes for microfiltration or ultrafiltration in conjunction with reverse osmosis and, in some cases, nanofiltration. Membrane properties, including pore size, wettability, surface charge, roughness, thermal resistance, chemical stability, permeability, thickness and mechanical strength, vary between membranes and applications. Advancements in membrane technology including new membrane materials, coatings, and manufacturing methods, as well as emerging membrane processes such as membrane bioreactors, electrodialysis, and forward osmosis have been developed to improve selectivity, energy consumption, fouling resistance, and/or capital cost. The purpose of this review is to provide a comprehensive summary of the role of polymeric membranes and process components in the treatment of wastewater to potable water quality and to highlight recent advancements and needs in separation processes. Beyond membranes themselves, this review covers the background and history of potable reuse, and commonly used potable reuse process chains, pretreatment steps, and advanced oxidation processes. Key trends in membrane technology include novel configurations, materials, and fouling prevention techniques. Challenges still facing membrane-based potable reuse applications, including chemical and biological contaminant removal, membrane fouling, and public perception, are highlighted as areas in need of further research and development.
Among the different technologies developed for desalination, the electrodialysis/electrodialysis reversal (ED/EDR) process is one of the most promising for treating brackish water with low salinity ...when there is high risk of scaling. Multiple researchers have investigated ED/EDR to optimize the process, determine the effects of operating parameters, and develop theoretical/empirical models. Previously published empirical/theoretical models have evaluated the effect of the hydraulic conditions of the ED/EDR on the limiting current density using dimensionless numbers. The reason for previous studies' emphasis on limiting current density is twofold: 1) to maximize ion removal, most ED/EDR systems are operated close to limiting current conditions if there is not a scaling potential in the concentrate chamber due to a high concentration of less-soluble salts; and 2) for modeling the ED/EDR system with dimensionless numbers, it is more accurate and convenient to use limiting current density, where the boundary layer's characteristics are known at constant electrical conditions. To improve knowledge of ED/EDR systems, ED/EDR models should be also developed for the Ohmic region, where operation reduces energy consumption, facilitates targeted ion removal, and prolongs membrane life compared to limiting current conditions. In this paper, theoretical/empirical models were developed for ED/EDR performance in a wide range of operating conditions. The presented ion removal and selectivity models were developed for the removal of monovalent ions and divalent ions utilizing the dominant dimensionless numbers obtained from laboratory scale electrodialysis experiments. At any system scale, these models can predict ED/EDR performance in terms of monovalent and divalent ion removal.
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•Empirical predictive models for ED/EDR were developed using dimensionless numbers.•Stanton number was a function of Peclet and dimensionless voltage in ED/EDR.•Presented models can be utilized in large-scale applications.•Selectivity of the ED/EDR process was defined in a new form based on Stanton number.
This study employs theory and experimental data from a laboratory-scale electrodialyzer to predict sodium chloride (NaCl) mass transport and concentration distribution along the electrodialyzer as a ...function of feed concentration, feed flow rate, applied voltage, and pressure. Moreover, a model was developed to predict the ion removal as a function of driving forces through solving the complete Navier-Stokes, continuity, and steady state Nernst-Planck equations by the finite difference numerical method. The findings of the experiments confirmed that concentration distributions are nonlinear along both the dilute and concentrate compartments. The results also demonstrated that increases in pressure and feed flow rate have a negative effect on salt removal, linear and nonlinear for pressure and flow rate, respectively. In the investigated ranges, higher voltage increased salt removal at a constant feed concentration.
Understanding the effects of operating factors on ion removal in the electrodialysis/electrodialysis reversal (ED/EDR) process can significantly benefit industrial applications, enabling process ...optimization through different combinations of operational factors. Several studies have shown the effects of specific operating factors on ion removal, and it has been established that superficial velocity influences ion removal. However, previous studies have yielded mixed results on whether increases in superficial velocity increase or decrease ion removal; also, since previous studies are based on laboratory-scale ED systems, the results may not be fully applicable to full-scale desalination due to differences in system characteristics such as membrane area, flow path, and degree of superficial velocity’s effect on ion removal. Therefore, this experimental study employs a pilot-scale EDR system that is very similar to a full-scale system in order to explore the effects of applied voltage, superficial velocity, and feed water temperature on ion removal. Additionally, a conceptual explanation is developed to explain the inconclusive results from previous research. The findings of this experiment confirmed that increases in superficial velocity decreased ion removal, and this result can help predict and optimize full-scale operations. In the investigated ranges, increasing voltage and temperature resulted in increased ion removal, while increasing superficial velocity resulted in decreased ion removal. The experiments were conducted at the Brackish Groundwater National Desalination Research Facility in Alamogordo, NM, USA on a General Electric Company pilot-scale EDR system with a maximum product flow rate of 45 L/min, using brackish water with a conductivity of 1,700 μS/cm.
Variations in functional parameters strongly affect the performance of the electrodialysis process, a promising approach for desalinating brackish water. Although the effects of operational factors ...have been qualitatively investigated in previously published works, the simultaneous effects of three important operational factors, applied voltage, superficial velocity, and temperature, have not yet been quantitatively described or presented in the form of a mathematical model. Therefore, the simultaneous effects of these operational parameters have not been shown in functional form in the previously published works. In this research, a laboratory-scale electrodialysis setup was used to qualitatively and quantitatively study the effects of operational factors by employing a set of full-factorial experiments with three replications at different levels of applied voltage per cell pair, superficial velocity, temperature, and feedwater composition. The nonlinear power-law functions were found for the effects of superficial velocity, applied voltage per cell pair, and initial feed concentration, while an Arrhenius-type function was found for the effect of temperature.
•Effects of functional parameters in ED process were quantitatively investigated.•Empirical predictive models for ion removal in ED was developed.•Nonlinear power-law functions were found for the effects of velocity and voltage.•An Arrhenius-type function was found for the effect of temperature.
•We compare EDR/RO energy consumptions and sensitivities under various conditions.•Product flow rate and feed salinity significantly affect energy consumption.•Temperature significantly affects only ...RO’s energy consumption, not EDR’s.•For low-TDS water, EDR uses less energy than RO; for high-TDS water, RO uses less.•We report the feasibility of off-grid EDR and RO systems and compare their costs.
To explore the techno-economic feasibility of powering remote, rural desalination systems with renewable energies, this study conducted pilot-scale experimental work and software modeling to identify the energy consumptions of two common brackish water desalination technologies – electrodialysis reversal (EDR) and reverse osmosis (RO) – when operated with different water salinities, flow rates, and temperatures. The pilot-scale experiments were conducted in parallel at the Brackish Groundwater National Desalination Research Facility in Alamogordo, New Mexico; for the software modeling, WATSYS software was used for EDR, and WinFlows software was used for RO. The experimental results showed that product flow rate and the salinity of feed water significantly affected the specific energy consumptions (SECs) of EDR and RO. The SEC of EDR is more sensitive to feed water salinity variations, as compared to the SEC of RO. The SEC sensitivities of EDR and RO to product flow rate were slightly different. The SEC of EDR was not significantly influenced by temperature variations, while the SEC of RO was affected significantly by temperature variations. With the energy requirements for these systems identified under a range of operating conditions, HOMER software was used to identify optimal renewable energy systems for powering the desalination technologies under each combination of operating conditions. Lastly, the total net present cost of each renewable energy system was calculated, and the most economical systems were identified. As determined by measured energy consumption and modeled energy production, solar energy can feasibly power off-grid ED/EDR and RO systems in regions with meteorological conditions similar to Alamogordo, New Mexico. For low-salinity water with solar power, EDR was far more efficient than solar-powered RO, with a total net present cost difference of 48–159%, if the blending is not an option for RO. For higher-salinity water, solar-powered RO was more efficient than solar-powered EDR, with a lower total net present cost.
•Equilibrium, kinetics, and thermodynamics of Cd(II) sorption using low-cost Sudangrass was studied for the first time.•Various modifying chemicals, i.e. acids, bases, and oxidizers, were used to ...improve sorption capacity and equilibrium time.•Modification using 0.05 M NaOH gave the best results due to the creation of carboxylate sites via ester saponification.•Regeneration of the modified sorbent was successfully done for one cycle using 0.5 M HNO3.
In an attempt to find inexpensive and effective biosorbents and modification methods, cadmium sorption ability of native Sorghum x drummondii, commonly called sudangrass, and its modified biomass was studied for the first time. From several modified biosorbents, 0.05 M NaOH-modified sudangrass performed the best and hence was used for further experiments. Both sorbents were characterized and various parameters were investigated on their sorption performance. Equilibrium time was reduced from 90 to 20 min after modification. Intra-particle diffusion and pseudo-second order kinetic models were found as best-fitting models for sudangrass and NaOH-modified sudangrass, respectively. Langmuir isotherm model described equilibrium data with the highest accuracy. Maximum monolayer adsorption capacity of cadmium onto sudangrass and NaOH-modified sudangrass was obtained as 1.52 and 7.76 mg g−1, respectively, showing a five-fold improvement for cadmium sorption. Sorption mechanism and thermodynamic investigations suggested that cadmium removal by modified sudangrass is a chemisorption and endothermic process, while cadmium removal by sudangrass is predominantly physisorption and exothermic. This study indicated that both native and modified sudangrass sorbents are capable of removing cadmium ions from aqueous solution with modified biosorbent having a much higher potential for this application.
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•Developing a novel single-pot synthesis of Zn(NH3)(CO3) single crystals based on urea hydrolysis.•Explaining the helical crystalline structure of Zn(NH3)(CO3).•Discovery of gas ...adsorption property for Zn(NH3)(CO3) for the first time.•Identifying selective CO2 separation from N2 and H2 and storage at near-atmospheric pressures by Zn(NH3)(CO3).•Hypothesizing a mechanism for the notable H4-type hysteresis of adsorption isotherm of Zn(NH3)(CO3).
This study explores the potential of Zn(NH3)(CO3) for selective CO2 separation. It develops a novel highly controllable single-pot synthesis approach based on urea hydrolysis and solvothermal aging to increase the feasibility of synthesizing Zn(NH3)(CO3), determines the structure of Zn(NH3)(CO3) in detail through single crystal X-ray diffraction and powder X-ray diffraction analyses, and performs adsorption analyses for the compound using N2, H2, and CO2 as adsorptives. Structural analyses show Zn(NH3)(CO3) to have an inorganic helical framework that consists of a small helix of (ZnOCO)2 and a big helix of (ZnOCO)4 with two ammines (NH3) pendant from every other zinc. In terms of adsorption capacity and CO2 selectivity, Zn(NH3)(CO3) adsorbed 0.550mmolg−1 CO2 at 293K and 4500mmHg, but only 0.047mmolg−1 N2 and 0.084mmolg−1 H2 at the same temperature and pressure. This behavior demonstrates considerable equilibrium selectivities – 31 and 63 – for separating CO2 from H2 and CO2 from N2, respectively. During adsorption, the pendant ammines act as the gates of check-valves: applied pressure opens the gates for adsorption, and during desorption, the gates are closed, trapping the adsorbates, until a reduction of pressure to near-atmospheric levels. Therefore, Zn(NH3)(CO3) exhibits low-pressure H4 hysteresis, indicating that the Zn(NH3)(CO3) framework can achieve gas storage at near-atmospheric pressures. Additionally, the compound proves structurally stable, with an adsorption decrease of 0.8% after 20 adsorption/desorption cycles – a factor that, considered with the other characteristics of Zn(NH3)(CO3), renders this compound a potential candidate for separating CO2 from H2 and N2.
Reverse osmosis (RO) systems offer a viable solution for treating brackish water (BW), a common but underutilized water resource. However, the energy-intensive nature of brackish water reverse ...osmosis (BWRO) systems poses affordability challenges to water supply, necessitating a focus on minimizing their energy consumption to support SDG6's goal of providing safe and affordable drinking water for all. This study addresses the critical need to minimize the specific energy consumption (SEC) of a typical BWRO system, defined as the energy consumed per unit of water recovered, mathematically and experimentally. Empirical models were developed proving there is a global minimum SEC while adjusting the operating conditions. Furthermore, we identified the key operating factors influencing SEC and their priority levels, along with their interactive effects. Notably, no prior study has discussed the significance and interaction of these operating factors (e.g., feed water salinity, temperature, pressure, flowrate and membrane permeability) on SEC of a BWRO system. Employing a full factorial experimental design with mixed levels of operating parameters, the study developed regression models that elucidate the mechanistic interaction between these parameters and system performance. Moreover, the models were validated experimentally, with a new dataset demonstrating their accuracy and reliability. ANOVA statistical analysis identified feed salinity, pressure, flow rate, feed flow rate×pressure, salinity×pressure, and temperature as influential operating parameters in reducing SEC, in descending order of importance. Operating within the determined optimum range resulted in a 36 % decrease in SEC and a more than fourfold increase in water recovery. The study's systematic approach and findings can be extrapolated to optimize the performance of other desalination technologies and diverse feed water types, contributing significantly to global water sustainability efforts.
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•The mechanistic interaction of input and output variables was studied in a BWRO.•Order of importance of significant parameters in reducing SEC:P, Qf, Cf, Qf × P, Cf,×P, T.•SEC models were developed, and validated with empirical data (R2 = 0.93, 0.95).•Adjusting the operating variables could minimize the SEC by up to 36 %.•Recovery increased >4 times when operated in the optimum operating region.
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