Salt Crystallization Research Articles

Effect of Wood Ash on salt Crystallization and Rapid Chloride Permeability Test (RPCT) in Mortar

Abstract: Ash by-products obtained from combustion of wood biomass are generally used in land filling for embankments, road/highway construction. It can be used as soil supplementing material to reduce the alkalinity of soil in agricultural lands. And it can also be used as raw material in the manufacturing of cement in cement industries. Many researches had been carried out to incorporate wood waste ash as a cement replacement material in the production of greener construction material (concrete/mortar) and also as a sustainable means of disposal for wood waste ash. Results of these researches indicated that wood waste ash can be effectively used as a cement replacement material for the production of structural concrete/mortar of acceptable strength and durability parameters. In the present study salt crystallization, rapid chloride permeability test are performed. The results shows As wood ash contains more amount of calcium oxides which are soluble in water and leached out and further react with sodium sulphate. That is why, on increasing the percentage of wood ash, loss in weight as well as loss in compressive strength and chloride ion permeability is high in all the cases but as we increase the percentage of wood ash, chloride ion permeability decreases

Boosting Water Evaporation by Construction of Photothermal Materials with a Biomimetic Black Soil Aggregate Structure.

Solar-driven interfacial evaporation is considered an efficient way to get fresh water from seawater. However, the low evaporation rate, surface salt crystallization, and low energy collection of the photothermal evaporation layer limit its further application in an outdoor freshwater field. And the aggregate structure design of the material itself is often ignored in solar-driven water evaporation. Black soil (BS), with a unique soil aggregate structure, is rich in tubular pores, which can be used for multilevel sunlight utilization and good capillary water transport. Based on the extraordinary photothermal properties and pumping capacity of BS, a reasonable unidirectional salt-collecting device is designed, which can realize long-term collection of mineral salts and continuous evaporation of seawater and generate electric energy in the continuous evaporation. Inspired by the unique aggregate structure, the photothermal material doping of halloysite and nigrosin will simulate the generation of this aggregate structure and retain a good water transport effect while obtaining multistage utilization of sunlight. The solar-driven evaporation rate of a nigrosin-halloysite solar steam generator is 1.75 kg m-2 h-1 under 1 kW m-2 mimic solar radiation; it can achieve stable salt leaching-induced voltage generation of 240 mV. This work demonstrates not only a solar evaporator that can continuously achieve desalination but also the design strategy of BS-like aggregate photothermal materials, which promotes the development of low-cost resource recovery and energy generation for practical outdoor seawater desalination.

Oriented porous hydrogel with excellent anti-salt and antibacterial properties for high-performance interfacial solar steam generation

In recent years, solar interfacial evaporation has drawn substantial attention in wastewater and seawater treatment, but it still requires intensive development in high-performance evaporators, particularly simultaneous with high anti-salt and antibacterial abilities to supply freshwater. In this work, a directionally channeled evaporator with excellent resistance to salt crystallization and microbial was designed and synthesized by using silver nanoparticles (AgNPs) / polydopamine (PDA) hydrogel via a simple freeze-dried method. The novel structure was proposed to enhance convection and accelerate water transport that prevents salt crystallization. PDA and AgNPs were deposited to achieve superb optical absorption, photothermal conversion and anti-biofouling ability. Therefore, the evaporation rate of the AgNPs-PDA hydrogel achieved 1.70 kg m−2 h−1 with a light-to-heat conversion efficiency of 90.3 %. Based on the efficient evaporation ability and especially structure of the AgNPs-PDA hydrogel, the evaporator presented a tolerance to high salt water and the stable evaporation performance of actual seawater evaporation during long-time application. Simultaneously, the addition of AgNPs endowed the AgNPs-PDA hydrogel evaporator with excellent antibacterial ability. Thus, these favorable properties endowed the special AgNPs-PDA hydrogel evaporator a great potential for obtaining efficient evaporation and simultaneously solving the fouling problem, especially to waterborne pathogens and salt crystallization in tanglesome applications.

Resolution by diastereomeric salts: Access to both enantiomers of racemic acid using the same enantiomer of resolving base.

Racemic carboxylic acid, a Diels-Alder cycloadduct derived from 5-bromo-3-phenyl-α-pyrone and acrylate dienophile, was resolved into enantiomers by diastereomeric salt crystallization. Quinidine was used as a sole resolving base. The salt of (+)-acid crystallized from aqueous acetonitrile solution. Once this salt was separated by filtration, quinidine salt with (-)-acid crystallized from mother liquor. As a result, both enantiomers of Diels-Alder cycloadduct were isolated in high enantiomeric purity.

Current Problems and Solutions for Solar‐Driven Interfacial Distillation from a Practical Perspective

AbstractSolar‐driven interfacial distillation (SDID) is becoming an effective green technology for the treatment and reuse of unconventional water sources in the past few years. However, the established design and detection of SDID systems may involve different problems regarding practical application. Herein, through a series of literature research, this work summarizes the current evaluation parameters of SDID performance and the distilled water quality, highlights the importance of evaporation and distilled water collection rate, emphasizes that volatile organic compounds would become a new pollution feature in evaporation process, and suggests that insoluble salt crystallization and microbial corrosion should be considered during the design phase to ensure the constant use of the solar evaporators.

Evaporation of Saline Droplets on a Superhydrophobic Substrate: Formation of Crystal Shell and "Legs".

We studied the evaporation-driven crystallization in the droplets of sodium acetate anhydrous (CH3COONa) aqueous solution, which were deposited on superhydrophobic substrates. The results reveal distinct crystallization behaviors between saturated and unsaturated droplets under identical experimental conditions. Specifically, unsaturated droplets could form a quasi-spherical crystal shell on the superhydrophobic substrate, while saturated droplets could develop crystal legs between the droplet and substrate when the crystal shell formed. Subsequently, the saturated droplet was lifted off the substrate by the growing crystal legs. The formation of crystal shell was closely associated with the evaporation from the droplet surface and the internal convection inside the droplet. The formation of crystal legs was induced by the heterogeneous nucleation effect caused by the substrate of SiO2 nanoparticles. These findings provide valuable insights into regulating the morphology of salt crystallization through adjustments in salt solution concentration and substrate surface structure.

Catkins based flexible photothermal materials for solar driven interface evaporation collaborative power generation

Solar driven interface evaporation co-generation is expected to simultaneously solve the shortage of freshwater resources and the energy crisis. Herein, based on the natural tubular structure of biomass catkins, we prepared catkins/polyaniline/copper oxide composite fiber-based evaporator (CBP-CuO). CBP-CuO has excellent hydrophobicity, and its thermal conductivity is about 0.0421 W m−1 K−1. The evaporation rate under one solar irradiation is 1.72 kg m−2 h−1 and the evaporation efficiency of CBP-CuO reaches 105.3%. During the 30 days high concentration salt tolerance test, there is almost no salt crystallization on the evaporator surface. Using the principle of thermoelectric effect, the power generation capacity of CBP-CuO is approximately 57.459 mV under 0.9 kW m−2. CBP-CuO 33has the advantages of economy, environmental protection, and recycling, and has great application potential in actual seawater desalination and production.

Comparative study on the similarity between ancient white bricks and the self-developed imitative white bricks

Many architectural heritages in China are built with ancient white bricks (AWB), which behave very differently from traditional blue and red bricks. Indeed, AWB buildings have undergone centuries of historical changes and weathering with time, and require urgent repair. Since replacing ancient bricks with imitative bricks when restoring heritage buildings has become a consensus, it is necessary to develop imitative white bricks (IWB) similar to AWB in many respects to be used for restoring ancient buildings. Therefore, this paper develops a novel IWB and analyses its similarity with the AWB by means of X-ray diffraction, X-ray fluorescence, mercury intrusion test, scanning electron microscopy, and ultrasonic pulse velocity. The results reveal that the self-developed IWB is highly similar to AWB in mineral and chemical composition, micro-morphology, internal appearance, apparent densities, water absorption rate, saturation coefficient, porosity, and these bricks are concentrated in micropores with similar radii. Besides, the durability is somewhat similar in terms of salt crystallization and resistance to freeze-thaw cycles. The IWB and AWB are classified as susceptible to salt crystallization, while good resistance to these white bricks' freeze-thaw cycles. The ultrasonic pulse velocity of the self-developed IWB along the height direction is close to the ultrasonic pulse velocity along other AWB directions. Besides, ultrasonic pulse velocity along the height direction is linearly correlated to the compressive strength of and the IWB and AWB, which has important reference significance for evaluating the mechanical properties of architectural heritages by ultrasonic non-destructive testing technology. These results can provide theoretical and technical support for the in-situ repair of damaged AWB and are significant for restoring and conserving brick masonry architectural heritages.

High-performance Janus evaporator based on self-healing hydrogels for salt-rejecting interfacial solar desalination

The solar interfacial evaporation is considered as an innovate and promising technology to overcome the water scarcity crisis. However, an army of problems are being presented in evaporator applicate on open water, which formats and deposits of salt crystallization at its surface during long-term evaporation and permanents damage causing by wave impact. In this study, a self-floating and durable Janus interfacial solar evaporator (ISE) based on self-healing hydrogel with salt-rejecting was demonstrated for the efficiency production of clean water. Benefiting from the decrease of water evaporation enthalpy in hydrogel-based ISE, water evaporation rates over 2.096 kg·m−2·h−1 and solar efficiency of 85.50 % are attained under 1 sun. Additionally, the evaporator of Janus structure effectively avoids the format and deposition of salt at photothermal layer, exhibiting positive salt-rejecting and purification in various wastewater for long-term evaporation. What is more, the performance and appearance of self-healing hydrogel-based ISE can be easily restored. An encouraging and cheering Janus evaporator was proved via integrating self-healing and damage-tolerant hydrogels for solar desalination and water purification, which exhibits exciting durability and lifetime.

A comprehensive assessment of durability and service life prediction of concrete structures in the simulated tidal zone of the South China Sea considering measures to enhance concrete durability

The island and reef area in the South China Sea is characterized by high temperature, high salinity, high humidity and windiness, which can accelerate the deterioration of concrete structures, requiring some measures to improve the durability of concrete. To improve the poor durability of concrete structures in the tidal zone of island and reef area in the South China Sea, the influence of multiple factors on concrete structures is investigated. The tests of mass, ultrasonic velocity, flexural strength and chloride ion content are used to analyze the deterioration of concrete and the service life of concrete structures. The results show that the performance of concrete under the simulated tidal environment of island and reef area is enhanced first and then attenuated, and the relationship of the mass retention, relative dynamic elastic modulus and strength retention between any two parameters is linear. Compared with concrete with a water cement ratio of 0.53 (C(-0.53)) in the paper, the deterioration degrees of C(-0.53) with calcium nitrite (CN), C(-0.53) with amino alcohol corrosion inhibitor (AA), C(-0.53) with hydrophobic pore-blocking ingredient corrosion inhibitor (HPA), C(-0.53) with salt crystallization inhibition (UMP), concrete with a water cement ratio of 0.31 (C-0.31) and concrete with a water cement ratio of 0.26 (C-0.26) decrease by 0.5%, 1.0%, 1.5%, 1.8%, 4.5% and 9.1% respectively. In addition, compared with only chloride diffusion coefficient, the multiparameter evaluation is more suitable for the chloride diffusion behavior in concrete under the simulated tidal environment of island and reef area. Compared with C(-0.53), the service life of CN, AA, HPA, UMP, C-0.31 and C-0.26 increase by at least 1.3 times, 1.9 times, 1.7 times, 6.7 times, 3.3 times and 5.5 times respectively. This study provides theoretical guidance and technical support for the durability of island and reef engineering.

Evaluating the Efficiency of Magnetic Treatment for Feed Water in Reverse Osmosis Processes.

The paper presents a new methodology for short-term (5-25 min) benchtop tests to evaluate the effectiveness of magnetic treatment of feed water for reducing mineral scaling on a reverse osmosis (RO) membrane. Scale deposition is measured at a controlled level of salt supersaturation in water flowing through an RO unit in once-through mode. A magnetic water conditioner is tested in a transient flow regime when variations of the permeate flux along the flow path are insignificant. Scale formation under these conditions is governed by salt crystallization on the membrane surface. The proposed method was implemented to investigate the influence of magnetic treatment on gypsum deposition on RO membranes in supersaturated aqueous CaSO4/NaCl solutions. The effects of magnetic water treatment on scale formation under our experimental conditions were found to be statistically insignificant with a confidence level of 95%. However, this outcome should not be considered to negate the potential efficiency of magnetic water treatment in specific applications. The proposed methodology of testing under a controlled level of salt supersaturation will also be useful for evaluating the efficiency of other water treatment technologies.

Spatial and temporal changes in microclimate affect disease distribution in two ancient tombs of Southern Tang Dynasty

Two tombs of the Southern Tang Dynasty (Qinling Tomb and Shunling Tomb), the most important cultural heritages in China, were built for emperors 1000 years ago and decorated with murals and stone sculptures. After their excavation in the 1950s, it was found that drastic fluctuations in the environment within the tombs had caused multiple diseases, such as salt efflorescence, powdering, and biodeterioration, which led to irreversible damage to the murals. This research comprised long-term (yearly) environmental monitoring and short-term (monthly) investigation into the distribution of salt crystallization and microbial growth within the two tombs. The objective was to unveil the relationship between the temporal and spatial distributions of the mural diseases and environmental characteristics while proposing a promising environmental regulation strategy for relic conservation. The results showed a gradual reduction in temperature fluctuation from the entrance to the back chamber and a distinct vertical stratification in relative humidity. The relative humidity in the upper areas of the tombs reached 100% during summer, while it averaged around 40–50% in the lower areas during winter. Consequently, significant condensation was observed on the ceiling in summer, whereas salt crystallization occurred on the murals in the lower space in winter. The distribution of these diseases was influenced by the airflow exchange between the interior and exterior. Furthermore, the structural disparities between the two tombs contributed to higher relative humidity and greater microorganism coverage in the Shunling Tomb compared to the Qinling Tomb. From the abovementioned findings, we suggest that microclimate control is essential for mitigating mural deterioration and should be paid more attention in the future.

MODERNIZATION OF THE AUTOMATED SYSTEM TECHNOLOGIAL PROCESS OF SALT EXTRACTION

"This article provides the development of a new automated system for the technological process of salt extraction, based on the principles of integrating existing technologies and innovative developments. The results of testing this system will be presented, an analysis of its effectiveness, economic benefits will be carried out, and recommendations for its use will be given. The paper considers the existing salt extraction technologies and automated control systems used in production, analyze their shortcomings and problems, raises issues related to product quality, energy efficiency, economy and safety of salt extraction technological processes. The technological process of salt crystallization is considered as a model. This model implies a two-stage adjustment of the cooling temperature of the hot salt solution at the outlet of the heat exchanger. This allows you to see the effectiveness of the implementation of the improved method of salt extraction. The paper will present an integrated approach to the problems of automating the technological process of salt extraction, which will provide new knowledge and competencies in this area. "

Effect of Phytate (InsP6) and Other Inositol-Phosphates (InsP5, InsP4, InsP3, InsP2) on Crystallization of Calcium Oxalate, Brushite, and Hydroxyapatite.

Pathological calcifications may consist of calcium oxalate (CaOx), hydroxyapatite (HAP), and brushite (BRU). The objective of this study was to evaluate the effect of phytate (inositol hexakisphosphate, InsP6), InsP6 hydrolysates, and individual lower InsPs (InsP5, InsP4, InsP3, and InsP2) on the crystallization of CaOx, HAP and BRU in artificial urine. All of the lower InsPs seem to inhibit the crystallization of calcium salts in biological fluids, although our in vitro results showed that InsP6 and InsP5 were stronger inhibitors of CaOx crystallization, and InsP5 and InsP4 were stronger inhibitors of BRU crystallization. For the specific in vitro experimental conditions we examined, the InsPs had very weak effects on HAP crystallization, although it is likely that a different mechanism is responsible for HAP crystallization in vivo. For example, calciprotein particles seem to have an important role in the formation of cardiovascular calcifications in vivo. The experimental conditions that we examined partially reproduced the in vivo conditions of CaOx and BRU crystallization, but not the in vivo conditions of HAP crystallization.

Physical and mechanical properties of Ignimbrite from Arucas, Canary Islands

This research is a contribution to the mineralogical and physical–mechanical characterisation of the ignimbrites from Arucas (Gran Canaria Island), used as building stones under the commercial names of "Piedra de Arucas Lomo Tomás de León" and "Piedra de Arucas Rosa Silva". This stone has been used for more than five hundred years and is part of the local architectural heritage, but has also been exported to other regions of the world. To perform this characterisation, a chemical analysis was carried out using X-ray fluorescence (XRF), mineralogical and petrographic properties were obtained using polarised optical microscopy (POM), X-ray diffraction (XRD) and scanning electron microscopy (SEM). Several physical properties were determined, namely: apparent density (AP), open porosity (OP), water absorption at atmospheric pressure (WA), water absorption by capillarity (WAC), ultrasound velocity (PWV) and colour. Mechanical properties were obtained through compressive strength (UCS), bending strength (BS), point load (PLT), indirect tensile (BTS) and energy at break (IR) tests. To evaluate the durability, the samples were subjected to salt crystallisation cycles (CS), SO2 action (AS) and salt spray (SS) and the abrasion resistance (AR) was determined. The results obtained show that, although both samples share the same lithology and belong to the same geological formation (Salic Formation, trachytic-phonolitic), they show very different properties. Porosity stands out as the property with the higher difference among the two studied varieties. Therefore, the application of these ignimbrites should be done accordingly, avoiding environmental conditions that promotes the wettability and/or the salt crystallisation.

The construction of composite hydrogel evaporator with interfacial heating performance and its application in water treatment

To meet the needs of sewage cleaning and clean drinking water, a multifunctional photothermal device is designed in this paper, which mainly includes the non-infiltrating layer of copper stearate, bismuth tungstate and copper oxide composite hydrogel. By improving the synthesis process, sheet-like copper stearate and flower-like bismuth tungstate were prepared, realizing the load of canvas, felt and fabric, with the contact angles reaching 158º, 162º and 161º, respectively. The nonwetting layer has the performance of not only selective oil removal, but also mechanical stability. Through traditional non-infiltrating materials, dyes cannot be degraded, while with the introduction of bismuth tungstate, superhydrophobic materials are given photodegradation properties, thus solving the recovery problem of powder photocatalysts. The photodegradation stability was demonstrated via multiple photodegradation processes by calculating the reaction kinetic coefficient, with a degradation efficiency of greater than 90%. The position of valence (1.9 eV) and conduction (-0.735 eV) band of bismuth tungstate was calculated based on Mott-Schottky curve, DRS and VB-XPS. With the construction of copper oxide composite hydrogel, the mechanical stability was improved and an efficiency of 1.76 kg•m−2•h−1 was obtained. The composite hydrogel device can also be used to treat the aqueous solutions containing metal ions and dyes, which operates stably in aqueous solutions containing 3.5% NaCl without salt crystallization, thus proving the application value of the photothermal device.

A polydopamine modified floral foam three-dimensional water evaporator for desalination via a directional self-assembly technology

Here, we prepared a water evaporator modified with polydopamine (PDA) using the directional self-assembly technology. The evaporator has a porous structure that can transport water through strong capillary action. With the modification of PDA, its light absorption rate is higher than 86% in the full spectral range of 200–2500 nm. Under one-sun irradiation, the water evaporator has a high evaporation rate (3.51 kg m−2h−1) and light-to-heat conversion efficiency (94.5%). Moreover, the evaporator has good salt suppression performance, and there is no salt crystallization during the evaporation process. It is an environmentally friendly, efficient, and reliable solar steam generator used for desalination and wastewater purification.

A simple, natural 3D honeycomb structure achieving high photothermal conversion and sustainable salt-resistance for efficient desalination and potential electricity generation

Excellent light absorption and suppressed salt crystallization are required for solar evaporators to operate continuously and efficiently. Herein, we report a waste biomass-derived solar evaporator (Le/CNTs-corn stalk) with natural 3D honeycomb structure and sustainable salt-resistance for efficient desalination and potential electricity generation. This simply fabricated 3D light-absorbing nanostructure greatly increases the light transmission distance, achieving significant boost in light absorption of 94.8 % and photothermal conversion efficiency of 92.5 %. Moreover, a spontaneous salt exchange capability between vascular bundles and laser engraved channels is developed according to the Hagen-Poiseuille's law. Salt concentration difference formed by the volume flowrate is alleviated to facilitate salt dissolution and prevent salt accumulation on the surface, enabling to evaporate effectively for 8 h even in 10 % salt solutions. In addition, tentatively inserted carbon nanotubes on its internal channel surface raises the total zeta potential and causes surface negative charge. A promising electricity generation potential is explored with continually generating a steady voltage of ∼136 mV. Our work provides a sustainable and massive strategy to realize efficient water production and simultaneous electricity generation using sufficient solar energy and biomass resources.

Transport phenomena and dynamics of an evaporating water meniscus at low heat fluxes

It is known that evaporation efficiency of novel solar thermal vapor generation/desalination systems can potentially increase by incorporating interfacial heat localization techniques utilizing porous wicks. The ensuing efficiency is a strong function of the geometric and thermal properties of the wicks and the ambient operating parameters. We investigate the role of these critical process parameters on the evaporation dynamics of pure and saline water from a single-layered wire mesh operating at low heat fluxes (1 kW/m2, 5 kW/m2and 10 kW/m2), which are typical for devices working on solar energy. Evaporation rates of water from stainless steel and nylon meshes are determined using non-invasive infra-red thermography and digital microscopy. A finite element based computational model is developed to understand local transient evaporation phenomenon at the microscale. Arbitrary Lagrangian-Eulerian (ALE) formulation is used to solve the coupled transport equations on a deforming computational grid, incorporating the Fick's law of diffusion at the evaporating water-air interface. With increasing heat fluxes, there is a deviation from purely diffusion-based transport. Higher evaporation rates are observed in meshes with smaller wire diameter and higher thermal diffusivity. In addition, the decisive role of local thin capillary films is exemplified. Simulations also indicate the diminutive role of thermocapillary convection during evaporation at such low input heat fluxes. Finally, we also investigate the effect of mesh size on the nature of salt crystallization. The evolution of salt concentration gradient at the microscale is computed that complements the experimental observations. Optimal exploitation of heat localization technique for enhanced evaporation necessitates understanding of microscale mesh level local transport effects.

Polyoxometalates‐Modulated Hydrophilic‐Hydrophobic Composite Interfacial Material for Efficient Solar Water Evaporation and Salt Harvesting in High‐Salinity Brine

Solar vapor generation (SVG) represents a promising technique for seawater desalination to alleviate the global water crisis and energy shortage. One of its main bottleneck problems is that the evaporation efficiency and stability are limited by salt crystallization under high‐salinity brines. Herein, we demonstrate that the 3D porous melamine‐foam (MF) wrapped by a type of self‐assembling composite materials based on reduced polyoxometalates (i.e. heteropoly blue, HPB), oleic acid (OA), and polypyrrole (PPy) (labeled with MF@HPB‐PPyn‐OA) can serve as efficient and stable SVG material at high salinity. Structural characterizations of MF@HPB‐PPyn‐OA indicate that both hydrophilic region of HPBs and hydrophobic region of OA co‐exist on the surface of composite materials, optimizing the hydrophilic and hydrophobic interfaces of the SVG materials, and fully exerting its functionality for ultrahigh water‐evaporation and anti‐salt fouling. The optimal MF@HPB‐PPy10‐OA operates continuously and stably for over 100 h in 10 wt% brine. Furthermore, MF@HPB‐PPy10‐OA accomplishes complete salt‐water separation of 10 wt% brine with 3.3 kg m−2 h−1 under 1‐sun irradiation, yielding salt harvesting efficiency of 96.5%, which belongs to the record high of high‐salinity systems reported so far and is close to achieving zero liquid discharge. Moreover, the low cost of MF@HPB‐PPy10‐OA (2.56 $ m−2) suggests its potential application in the practical SVG technique.