Solar-Powered High-Performance Lignin-Wood Evaporator for Solar Steam Generation

Recent research on wood-based solar evaporators has made great progress and significant breakthroughs have been made in using lignin as a photothermal material; however, the intensity change mechanism regarding the conjugate structure of lignin is almost never mentioned. This study innovatively proposes a mechanism to explain the changes in conjugate intensity that occur before and after lignin dissolution and fabricates a lignin/wood-based solar evaporator (LWE) using an all-wood-based material that is salt-tolerant and has long-term serviceability. Lignin in the evaporator serves not only as a photothermal material for converting light energy into heat energy but also as a reinforcement for the evaporator's structural strength. Adding lignin changes the original structure of balsa wood, increasing the proportion of intermediate water in the LWE, thereby lowering the enthalpy of water evaporation. The optimized LWE with an enhanced desalination capability, dye removal property, and high stability exhibits full-spectrum solar absorption of about 83.6%, a photothermal conversion efficiency of 91.74%, and an evaporation efficiency of 1.93 kg m⁻² h⁻¹, which surpasses most wood-based evaporators. This study demonstrates that all-wood-based materials can be used to prepare evaporators with excellent performance, providing a new approach to address freshwater depletion.     

Incipient crystallization of sparingly soluble salts on membrane surfaces: The case of dead-end filtration with no agitation

This paper aims at contributing to development of reliable criteria for determining the onset of scaling on desalination membranes. A novel approach is proposed to investigate incipient crystallization on membranes through modeling and RO filtration experiments. The evolution of membrane surface concentration of rejected ionic species (e.g. Ca²⁺, CO₃²⁻) is theoretically determined, and coupled with a detailed kinetic model for nucleation and growth of particles on the membrane. Model results contribute to our understanding of this problem and are in general accord with experimental data on membrane surface crystal density and mean size. Experimental data and model results show that incipient crystallization on RO membrane surfaces, when the bulk supersaturation ratio is maintained near its critical value (S ~ 1), is controlled by fluid permeation, and that the “induction time” may be insignificant under typical RO conditions. This work also suggests that the ability to determine the onset of crystallization on membranes is dependent on the combined sensitivity and adequate spatial resolution of the experimental technique employed, which explains the significant uncertainty associated with the reported in literature “induction period” data of different origin. Directions for future research are discussed.     

A stable and flexible carbon black/polyethyleneimine-bacterial cellulose photothermal membrane for high-efficiency solar vapor generation

Although various special materials have been exploited for enhancing evaporation performance of a solar vapor generation system, their practical applications could be greatly limited by structure destruction due to the seawater corrosion and external mechanical forces. In this work, we have developed a carbon black/polyethyleneimine-bacterial cellulose (CPB) membrane with vacuum filtration method to simultaneously enhance the strength and evaporation performance of solar vapor generation system, by applying carbon blacks as the photo-thermal conversion material, bacterial cellulose as the skeleton material for enhancing the structure strength, and polyethyleneimine (PEI) for tailoring the water absorption capacity. Effects of carbon black particle concentrations and PEI concentrations were probed, respectively, for optimizing the light absorption capacity and water absorption capacity in laboratory. Furthermore, the outdoor experiments were carried out to evaluate the strength and evaporation performances of CPB membrane. Results show that the evaporation efficiency of the CPB membrane could reach about 85.05% and 81.89% in the lab and outdoor under one sun irradiation. Additionally, a force of 59.37 MPa and folding more than 100 times will not break the structure of CPB membrane, which confirms the preferable structure strength. This superior CPB membrane, together with its low cost, simple fabrication, excellent mechanical properties, scalability and desalination ability, provides a feasible way for practical applications.     

Feasibility analysis and capability characterization of a novel hybrid flash-binary geothermal power plant and trigeneration system through a case study

This study presents and evaluates the feasibility of a novel hybridization of modified Kalina cycle, reverse osmosis desalination, and low-temperature water electrolysis utilizing geothermal energy to yield power, distilled water, and hydrogen, respectively. The scientific impact of the current work has been improved considering the features of Sabalan flash-binary geothermal wells in Iran as a real model through a case study. In addition to designing a novel setup, the smart use of multi-heat recovery technique, modifying the base cycle, and utilizing a part of generated distilled water to produce hydrogen by the electrolyzer are the other structural originalities, distinguishing the current work from the previous studies. The suggested system is scrutinized via a parametric study and optimized based on a genetic algorithm. The parametric study demonstrated that the highest sensitivity of varying the performance criteria of the whole system is attributed to the change in flash tank pressure. Moreover, the multi-objective optimization led to achieving the exergy efficiency and trigeneration gain output ratio as 51.3% and 1.7 for the system, respectively. Furthermore, the system was able to produce 4795 kW of power, 5.3 kg/h of hydrogen, and 19.9 kg/s of distilled water.     

Exceptional Water Desalination Performance with Anion‐Selective Electrodes

Capacitive deionization (CDI) typically uses one porous carbon electrode that is cation adsorbing and one that is anion adsorbing. In 2016, Smith and Dmello proposed an innovative CDI cell design based on two cation‐selective electrodes and a single anion‐selective membrane, and thereafter this design was experimentally validated by various authors. In this design, anions pass through the membrane once, and desalinated water is continuously produced. In the present work, this idea is extended, and it is experimentally shown that also a choice for anion‐selective electrodes, in combination with a cation‐selective membrane, leads to a functional cell design that continuously desalinates water. Anion‐selective electrodes are obtained by chemical modification of the carbon electrode with (3‐aminopropyl)triethoxysilane. After chemical modification, the activated carbon electrode shows a substantial reduction of the total pore volume and Brunauer–Emmett–Teller (BET) surface area, but nevertheless maintains excellent CDI performance, which is for the first time that a low‐porosity carbon electrode is demonstrated as a promising material for CDI.     

Determination of rational design parameters of a multi-stage solar water desalination still using transient mathematical modelling

The paper describes the experimental investigations of the performance of a multi-stage water desalination still connected to a heat pipe evacuated tube solar collector with aperture area of 1.7 m². The multi-stage solar still water desalination system was designed to recover latent heat from evaporation and condensation processes in four stages. The variation in the solar radiation during a typical mid-summer day in the Middle East region was simulated on the test rig using an array of 110 halogen floodlights covering the area of the collector. The results of tests demonstrate that the system produces about 9 kg of fresh water per day and has a solar collector efficiency of about 68%. However, the overall efficiency of the laboratory test rig at this stage of the investigations was found to be at the level of 33% due to excessive heat losses in the system. The analysis of the distilled water showed that its quality was within the World Health Organization guidelines. The still's operation was numerically simulated by employing a mathematical model based on a system of ordinary energy and mass conservation differential equations written for each stage of the still. A computer program was developed for transient simulations of the evaporation and condensation processes inside the multi-stage still. Experimental results obtained and theoretical predictions were found to be in good agreement. The results on the determination of rational design dimensions and number of stages of the still for a given aperture of the solar collector are also presented in this work.     

酪蛋白酶解液的脱盐纯化方法研究

研究了DA201-C，NKA-Ⅱ，AB-8，XAD1180，XAD16和HZ-816六种大孔吸附树脂在酪蛋白酶解液吸附和解吸附过程中的脱盐作用。在了解树脂物理参数的基础上，通过静态吸附实验，筛选出脱盐效果最佳的树脂和洗脱液，然后进行动态吸附实验研究。结果表明，DA201C对酪蛋白酶解液的脱盐是最佳的，而且采用70％乙醇溶液为洗脱剂时洗脱率和脱盐率均较高。