Wax Crystals Research Articles

Evaporative Drying Induced Self-Assembly of Epicuticular Wax: A Biomimetic Approach in Tuning Surface Roughness.

Epicuticular wax is an example of a naturally created functional material that forms a layer on the outermost surface of plants with the objective to protect them from adverse environmental conditions, such as UV-solar radiation, uncontrolled water loss, microbial attacks, and so forth. Their functionalities are often attributed to the chemical composition of the wax as well as the physical structuration formed by the wax crystals on the surface. With this work, we present a simple, one-step biomimetic approach to replicate similar surface structures, on model substrate, using wax extracted from Euphorbia Cerifera (Candelilla wax). First, we describe formation of structured wax due to self-assembly induced by evaporative drying on quartz plates. Subsequently, we highlight the fundamental physical parameters required to tune the surface morphology. Our experiments reveal that it is possible to achieve considerably diverse surface morphologies depending on the solvent properties and deposition temperature. This diversity is due to the kinetics of recrystallization of wax during evaporation of solvent which, in turn, is primarily driven by the solubility of wax as well as evaporation rate of the solvent. Thus, the final morphology that we obtain is an interplay between recrystallization kinetics and solvent evaporation. Additionally, the degree of crystallinity of the structured films could also be tuned by solvent polarity. Surprisingly, X-ray diffraction indicates that the crystalline structure at the molecular level remains similar to that of bulk Candelilla wax. Our results provide fundamental insights into the replication of epicuticular wax films and identification of tuning parameters to obtain different surface morphologies with the same wax material for potential bioinspired multifunctional coatings in cosmetic applications.

Mechanism of self-recovery of hydrophobicity after surface damage of lotus leaf

The surfaces of lotus leaves with micro- and nano-waxy cuticle structures are superhydrophobic and possess a self-healing ability to regain hydrophobicity after damage. Inspired by this phenomenon, the problem of water-repellent coatings used in natural environments failing to perform after damage can be solved if these coatings are endowed with rapid self-repair and self-growth functions. However, there has been almost no exploration into the hydrophobicity self-repair process in lotus leaves. The changes in surface morphology during the hydrophobicity recovery process are not understood. There is a lack of research on the hydrophobicity recovery in lotus leaves. In this study, the damage and recovery experiments on lotus leaf surfaces were carried out in an artificial climate chamber, and the water repellency recovery process and typical water repellency roughness parameters regained time were obtained. Upon analyzing the differences in the recovery process of different damage types, the recovery mechanism after lotus leaf surface damage was obtained. Finally, it was found that the microscopic roughness determined the static contact angle (WCA) of the lotus leaf surface, and the nanoscopic roughness determined the rolling angle (SA). The dual factors of the recovery of the extruded epidermal tissue and the regeneration of the epidermal wax crystals determined the hydrophobicity recovery process in damaged lotus leaves.

Modeling wax deposition in pipes: Developing a closure relationship for improving the prediction accuracy

Wax deposition remains one of the most challenging flow assurance issues faced by the oil and gas industry. The first cases of paraffin deposition problems in pipelines started to draw attention more than 50 years ago. However, no unequivocal model for its prediction has yet been proposed and accepted. The most used models for paraffin phenomenon prediction usually return over or under-predictions up to 100% in relative errors. Accurate prediction of this phenomenon will lead to proper flowline sizing, insulation requirements, pigging strategies, chemical treatments, etc. With the recent improvements in mechanistic understanding of wax deposition mechanisms based on in-situ microscopic visualization, it became clear that precipitated wax crystals occur within the boundary layer. Therefore, more than one mechanism governs the deposition process. These observations are the core for proposing a new estimation model that accounts for wax crystal precipitation. The model determines the concentration of precipitated crystals of wax through a material balance involving the soluble amount of wax in the system, the degree of supersaturation, and the precipitation rate constant (kp). Deposition data obtained from a laboratory-scale flow loop was used to validate the proposed model, resulting in great improvement in the relative errors between estimated and measured values for deposit thickness and wax fraction. Comparatively, the SD (Santos-Daraboina) Model resulted in predictions with relative errors as low as 12.8% against experimental data, while the FMT model, in some cases, resulted in overpredictions up to 299%.

Thermoresponsive Behavior of Binary Waxes

AbstractIn this study, we investigated the thermoresponsive behavior of two different binary wax compositions of commercially available natural candles. The chemical nature of carbon bonds in the fatty acid chains of the natural wax component effectuate a different hygroscopic behavior, as confirmed by NMR analysis. The phase transitions of polymorphic stearin‐rapeseed and stearin‐coconut wax composites were tracked by DSC‐TGA and VT‐XRD. The reduction in the eutectic temperatures of wax composites during the second heating cycles of DSC measurements was correlated with the length of fatty acid chains in rapeseed and coconut waxes, as well as their co‐crystallization kinetics with stearin. Mechanical and hygroscopic behavior of the binary waxes were examined at elevated temperatures between 23 °C and 45 °C using QCM‐D. Voigt viscoelastic model was employed to reveal the soft and rigid textures of wax composites. The hydrophilic behavior of the rapeseed wax composite changed to hydrophobic when the co‐crystallized and individual stearin melted above 35 °C. Activation energies required for melting wax crystals were calculated to be 51±3 kJ mol−1 for pure rapeseed wax, 373 kJ mol−1 for co‐crystallized rapeseed and stearin waxes, and 244 kJ mol−1 for co‐crystallized coconut and stearin waxes, using Arrhenius method with the QCM‐D data.

Pickering stabilization of water-in-crude oil emulsions by paraffin wax crystals: Insights from X-ray scattering

Previous studies suggest asphaltenes are active materials at the oil-water interface, affecting the formation and stability of crude oil emulsions. However, even oils of low asphaltene content generate stable emulsions, indicating the involvement of other oil fractions. Due to the role of paraffin waxes as Pickering stabilizers or gel network formers in emulsions from other applications, this study explores their stabilization capacity in water-in-oil (W/O) emulsions and their interaction with other fractions with interfacial activity. The extraction and physicochemical characterization of paraffin waxes from two Brazilian crude oils allowed us to correlate their properties with the emulsification of both crude and model oils. Removal of asphaltenes enhances emulsion stability. Emulsion preparation with crude oils without waxes and asphaltenes demonstrates the participation of other amphiphilic components in emulsion formation, whereas waxes are necessary for their stabilization. Experiments with emulsions formed by a model oil confirmed the combined action of waxes and an amphiphilic material in the formation and stabilization of the interfacial film. However, the combination of waxes and asphaltenes are ineffective. Small-angle X-ray scattering (SAXS) analysis revealed that waxes only form a lamellar structure when highly purified, suggesting Pickering stabilization rather than the formation of a gel network. In conclusion, polar oil fractions other than asphaltene play a crucial role in emulsion formation, whereas paraffin wax provides Pickering stabilization, even beyond the wax appearance temperature (WAT). This study enhances our understanding of the mechanisms governing waxy Brazilian crude oil emulsions.

La2O3 Nanoparticles Can Cause Cracking of Tomato Fruit through Genetic Reconstruction.

La2O3 nanoparticles (NPs) have shown great potential in agriculture, but cracking of plant sensitive tissue could occur during application, resulting in a poor appearance, facilitating entry for insects and fungi, and increasing economic losses. Herein, exocarp cracking mechanisms of tomato (Solanum lycopersicum L.) fruit in response to La2O3 NPs were investigated. Tomato plants were exposed to La2O3 NPs (0-40 mg/L, 90 days) by a split-root system under greenhouse condition. La2O3 NPs with high concentrations (25 and 40 mg/L) increased the obvious cracking of the fruit exocarp by 20.0 and 22.7%, respectively. After exposure to 25 mg/L La2O3 NPs, decreased thickness of the cuticle and cell wall and lower wax crystallization patterns of tomato fruit exocarp were observed. Biomechanical properties (e.g., firmness and stiffness) of fruit exocarp were decreased by 34.7 and 25.9%, respectively. RNA-sequencing revealed that the thinner cuticle was caused by the downregulation of cuticle biosynthesis related genes; pectin remodeling, including the reduction in homogalacturonan (e.g., LOC101264880) and rhamnose (e.g., LOC101248505), was responsible for the thinner cell wall. Additionally, genes related to water and abscisic acid homeostasis were significantly upregulated, causing the increases of water and soluble solid content of fruit and elevated fruit inner pressure. Therefore, the thinner fruit cuticle and cell wall combined with the higher inner pressure caused fruit cracking. This study improves our understanding of nanomaterials on important agricultural crops, including the structural reconstruction of fruit exocarp contributing to NPs-induced cracking at the molecular level.

Synthesis of terpolymer from Helianthus annuus (natural oil) and evaluation as pour point depressant and viscosity reducer on Indian crude oil

Pour Point Depressant is introduced to crude oil at ppm level to overcome transportation problem of crude oil because of its complex chemical structure. Synthesized PPDs improve flow property, viscosity and also improve its numerous parameters to improve performance of crude oil. Low molecular weight and high molecular weight, copolymer having better PPD types. In present work, synthesized Terpolymer, from natural source, was formed from the reaction with Helianthus annuus oil and ester of Erucic Acid with various fatty alcohol. It was evaluated for its properties on Indian waxy crude oils, i.e., From Limbodra well. Structure and molecular weight of synthesized polymer was confirmed by Spectral data and Gel permeation chromatography (GPC). Also its effect on crude oil was evaluated by Rheological studies, SARA Analysis, Pour point depressant effect. Cross–polarizing microscopic studies were performed to study changes in morphology of wax crystals in crude oil with and without additive. A zero friction advanced Rheometer AR-500 was used to determine the viscosity by applying Bingham plastic-flow model.

Broad Chain-Length Specificity of the Alkane-Forming Enzymes NoCER1A and NoCER3A/B in Nymphaea odorata.

Many terrestrial plants produce large quantities of alkanes for use in epicuticular wax and the pollen coat. However, their carbon chains must be long to be useful as fuel or as a petrochemical feedstock. Here, we focus on Nymphaea odorata, which produces relatively short alkanes in its anthers. We identified orthologs of the Arabidopsis alkane biosynthesis genes AtCER1 and AtCER3 in N. odorata and designated them NoCER1A, NoCER3A and NoCER3B. Expression analysis of NoCER1A and NoCER3A/B in Arabidopsis cer mutants revealed that the N. odorata enzymes cooperated with the Arabidopsis enzymes and that the NoCER1A produced shorter alkanes than AtCER1, regardless of which CER3 protein it interacted with. These results indicate that AtCER1 frequently uses a C30 substrate, whereas NoCER1A, NoCER3A/B and AtCER3 react with a broad range of substrate chain lengths. The incorporation of shorter alkanes disturbed the formation of wax crystals required for water-repellent activity in stems, suggesting that chain-length specificity is important for surface cleaning. Moreover, cultured tobacco cells expressing NoCER1A and NoCER3A/B effectively produced C19-C23 alkanes, indicating that the introduction of the two enzymes is sufficient to produce alkanes. Taken together, our findings suggest that these N. odorata enzymes may be useful for the biological production of alkanes of specific lengths. 3D modeling revealed that CER1s and CER3s share a similar structure that consists of N- and C-terminal domains, in which their predicted active sites are respectively located. We predicted the complex structure of both enzymes and found a cavity that connects their active sites.

Effective inhibition of crystal growth during wax deposition using CTAB‐grafted faujasite nanoparticles

AbstractIn this work, we developed cetrimonium bromide (CTAB)‐grafted faujasite nanoparticles (C‐g‐F) as wax inhibitors for the deposits that were formed from a model oil system consisting of 5 wt.% paraffin wax in toluene. Our developed nanomaterials were fully characterized, hydrophobically modified, and their deposition inhibition performance compared with virgin CTAB was investigated in a model waxy oil through cold finger setup (CF), differential scanning calorimetry (DSC), cold flow yield strength, and cross‐polarized microscopy (CPM). Applying our nano‐inhibitors at a concentration of 100 ppm led to more than 50 wt.% inhibition and a 30% reduction of deposit cold yield strength. Interestingly, the presence of FAU nanoparticles in the core structure of C‐g‐F contributed to better dispersibility, enhancing surface wettability (reducing interfacial tension with wax crystals), facilitating inhibitions, and preventing co‐crystallization greater than the surfactant alone. The morphological analysis results showed that C‐g‐F, due to their novel surface features, could suppress the unordered wax crystals from networking, resulting in uniform spherical‐like wax aggregates. Hence, the application of tiny concentrations of C‐g‐F (10 to 300 ppm) outperformed stand‐alone surfactants in nucleating the wax crystals.

Controlling the wax crystallization behaviors via the ratio of phenyl to aliphatic branches in block copolymer synthesized by RAFT copolymerization

AbstractThe precipitation and deposition of waxes in high waxy crude oil often result in the low throughput and clogging of pipeline. Adding polymers is a practical approach to solve these problems. In this study, poly(styrene‐co‐docosyl maleate)s (PSDMs) were synthesized by reversible addition‐fragmentation chain transfer polymerization. The chemical structure and molecular weight of copolymers were characterized using Fourier infrared spectroscopy, 1H nuclear magnetic resonance spectroscopy, and gel permeation chromatography. The ratio of phenyl to aliphatic branches varies from 10:8 to 25:8. The crystallization and morphology of waxes in model oil were investigated by x‐ray diffraction, differential scanning calorimetry, and polarized light microscopy. The cold flow behaviors of crude oil were evaluated by rheological methods. With the increase of the ratio of phenyl to aliphatic branches, the crystallinity, viscosity, and yield stress of crude oil first increase and then decrease. In the presence of PSDM‐2, the crystallinity and enthalpy of phase transition (ΔH) are reduced by 44.2% and 48.9%. Thus, the pour point, viscosity, and yield stress of crude oil are reduced by 6.0°C, 76.8% and 77.4%, respectively. Therefore, well‐defined PSDMs are promising to be remarkable flow improvers for waxy crude oils.

The cuticular wax on sorghum straw influenced soil microbial diversity and straw degradation in soil

The cuticular waxes cover living plant surface but the ecological significance of cuticular wax in crop straw returning to soil remains uncertain. This study focused on sorghum straw to investigate the bioactivity of cuticular waxes in the soil system. The surface of sorghum leaf, sheath and stem organs was covered with epicuticular wax crystals, which present a dull and glaucous wax layer. The leaf surface with wax exhibited an average contact angle of 83°, while after the wax removal the contact angle decreased to 53° on average, showing hydrophobic surface on the sorghum leaf. In total, six wax classes were identified across all organs, including aldehydes, alkanes, fatty acids, primary alcohols, sterols, and minor triterpenoids. The total wax coverage on leaves was 1.5 μg·cm−2, which was significantly lower than that on sheaths (20.6 μg·cm−2) and stems (6.3 μg·cm−2). The wax addition increased the proportions of Actinobacteria and Firmicutes by 24.42 % and 78.02 %, whereas decreased Proteobacteria and Acidobacteria by 16.32 % and 23.16 % on day 14 under higher wax rate. The microbial communities inhabiting returned straw surfaces also differed significantly between wax-retrained and wax-removed straw, as well as among leaf, stem, and sheath components, and at various decomposition stages. Wax addition increased soil microbial biomass carbon and nitrogen by 56.76 % and 25.60 % at higher rate, and soil enzyme activities (i.e., soil urease, soil acid phosphatase activity, soil sucrase activity). Wax removal significantly increased the decomposition rate of dry matter by 24.28 % and crude fiber by 27.22 % on day 154. These findings demonstrate that plant cuticular waxes maintain their bioactivities after entering the soil, which broadens our knowledge of the roles of plant cuticular waxes in ecosystems. Therefore, selecting efficient wax-degrading microorganisms would accelerate the nutrient cycling of crops in soil system.

Transcriptome Analysis Reveals Drought-Responsive Pathways and Key Genes of Two Oat (Avena sativa) Varieties.

To cope with the yield loss caused by drought stress, new oat varieties with greater drought tolerance need to be selected. In this study, two oat varieties with different drought tolerances were selected for analysis of their phenotypes and physiological indices under moderate and severe soil drought stress. The results revealed significant differences in the degree of wilting, leaf relative water content (RWC), and SOD and CAT activity between the two oat genotypes under severe soil drought stress; moreover, the drought-tolerant variety exhibited a significant increase in the number of stomata and wax crystals on the surface of both the leaf and guard cells; additionally, the morphology of the guard cells was normal, and there was no significant disruption of the grana lamella membrane or the nuclear envelope. Furthermore, transcriptome analysis revealed that the expression of genes related to the biosynthesis of waxes and cell-wall components, as well as those of the WRKY family, significantly increased in the drought-tolerant variety. These findings suggest that several genes involved in the antioxidant pathway could improve drought tolerance in plants by regulating the increase/decrease in wax and cell-wall constituents and maintaining normal cellular water potential, as well as improving the ability of the antioxidant system to scavenge peroxides in oats.

Studying the effects of asphaltene oxidation on wax crystallization and rheological properties in waxy crude oils

Oxidation in crude oil production is unavoidable. Oxidized asphaltenes, interacting with waxes during crystallization, profoundly alter wax precipitation and gel behavior in crude oils. This research evaluated the impact of asphaltene oxidation on the wax precipitation characteristics and rheological properties of waxy crude oils during the processes of crude oils extraction and transportation. A comprehensive structural characterization of the asphaltenes was conducted, revealing an increase in aromaticity and a reduction in the length and abundance of aliphatic chains following oxidation, accompanied by the formation of larger asphaltene aggregates. Subsequently, an investigation into the wax precipitation behaviors of waxy model oils showed that asphaltenes were involved in the crystallization processes of wax molecules, which had a minor impact on wax precipitation characteristics (crystallization and crystallization enthalpy). However, it had a significant influence on the rheological properties (pour point, flow curve and gel strength) of the systems. And it was also observed that the degree of influence was dependent on the structure and composition of the given asphaltenes and waxes. Asphaltenes with abundant aliphatic chains (before oxidation) tended to assume favorable positions during the crystallization process, which interfered to some extent with the normal growth of wax crystals and resulting in a transition from a “strong gel” to a “weak gel” network structure of wax crystals. Conversely, the oxidized asphaltenes with a high aromaticity exhibited a greater interference with wax crystal growth. This interference not only more effectively hindered the establishment of the wax crystal network but also prompted the formation of an “extremely fragile gel structure”.

MdBT2 regulates nitrogen-mediated cuticular wax biosynthesis via a MdMYB106-MdCER2L1 signalling pathway in apple.

Cuticular waxes play important roles in plant development and the interaction between plants and their environment. Researches on wax biosynthetic pathways have been reported in several plant species. Also, wax formation is closely related to environmental condition. However, the regulatory mechanism between wax and environmental factors, especially essential mineral elements, is less studied. Here we found that nitrogen (N) played a negative role in the regulation of wax synthesis in apple. We therefore analysed wax content, composition and crystals in BTB-TAZ domain protein 2 (MdBT2) overexpressing and antisense transgenic apple seedlings and found that MdBT2 could downregulate wax biosynthesis. Furthermore, R2R3-MYB transcription factor 16-like protein (MdMYB106) interacted with MdBT2, and MdBT2 mediated its ubiquitination and degradation through the 26S proteasome pathway. Finally, HXXXD-type acyl-transferase ECERIFERUM 2-like1 (MdCER2L1) was confirmed as a downstream target gene of MdMYB106. Our findings reveal an N-mediated apple wax biosynthesis pathway and lay a foundation for further study of the environmental factors associated with wax regulatory networks in apple.

Study on the Effect of Nano Pour Point Depressant on Wax Oil Crystallization

The influence of nano pour point depressant (NPPD) on crude oil containing wax is primarily manifested through their interaction with the wax constituents. This study examines the depressant's effects using a polarizing microscope and an atomic force microscope (AFM) to assess morphological and structural changes in the wax crystals within the oil, both before and after the addtion of the NPPD. Additionally, a surface tensiometer measured surface tension, while a rheometer evaluated viscosity and modulus alterations. These methods facilitated insights into NPPD's mechanistic effects. The interaction process between crude oil wax crystal molecules and the main components of NPPD was simulated using JOCTA molecular dynamics simulation software, and the highest interaction strength between benzenesulfonic acid groups and crude oil wax crystal molecules was determined. The findings indicate that the addition of the NPPD alters the growth patterns and crystalline structure of the wax in the oil. Initially, the wax crystals present as flaky, predominantly single molecular layer lamellae with a thickness of approximately 100 nm. Post-treatment, the wax crystals adopt a flattened lamellar configuration, composed of multilayer lamellae, with a reduced thickness of within 10 nm and exhibiting short-range order. AFM height maps reveal an increase in the average roughness of the wax oil correlated with the addition of the NPPD across different sampling lengths. Surface tension measurements demonstrate that the wax oil doped with the NPPD exhibits lower surface tension than undoped oil, with the surface tension decreasing as the temperature increases.

Probing the interaction between asphaltene-wax and its effects on the crystallization behavior of waxes in heavy oil via molecular dynamics simulation

High content of asphaltenes and waxes leads to the high pour point and the poor flowability of heavy oil, which is adverse to its efficient development and its transportation in pipe. Understanding the interaction mechanism between asphaltene-wax is crucial to solve these problems, but it is still unclear. In this paper, molecular dynamics simulation was used to investigate the interaction between asphaltene-wax and its effects on the crystallization behavior of waxes in heavy oil. Results show that molecules in pure wax are arranged in a paralleled geometry. But wax molecules in heavy oil, which are close to the surface of asphaltene aggregates, are bent and arranged irregularly. When the mass fraction of asphaltenes in asphaltene-wax system (ωasp) is 0–25 wt%, the attraction among wax molecules decreases and the bend degree of wax molecules increases with the increase of ωasp. The ωasp increases from 0 to 25 wt%, and the attraction between asphaltene-wax is stronger than that among waxes. This causes that the wax precipitation point changes from 353 to 333 K. While the ωasp increases to 50 wt%, wax molecules are more dispersed owing to the steric hindrance of asphaltene aggregates, and the interaction among wax molecules transforms from attraction to repulsion. It causes that the ordered crystal structure of waxes can't be formed at normal temperature. Simultaneously, the asphaltene, with the higher molecular weight or the more hetero atoms, has more obvious inhibition to the formation of wax crystals. Besides, resins also have an obvious inhibition on the wax crystal due to the formation of asphaltene-resin aggregates with a larger radius. Our results reveal the interaction mechanism between asphaltene-wax, and provide useful guidelines for the development of heavy oil.

Study on microstructure evolution of waxy crude oil emulsions under dynamic cooling conditions.

A rheo-microscopy in situ synchronous measurement system was utilized to investigate the dynamic behavior of water droplets in W/O waxy crude oil emulsions subjected to dynamic cooling conditions, the microstructural evolution of water droplets aggregates can be categorized into three stages based on the various forms of wax crystals. The results show that under the joint action of wax crystals and water droplets, the water droplets aggregation trend and complexity in the system are negatively correlated with the changes of temperature and shear rate, and the water droplets movement behavior is positively correlated with the changes of temperature and shear rate. As the temperature decreases, the minimum edge distance of water droplets decreases by a maximum of 32.1%, the specific surface area (SA) decreases by a maximum of 12.0%, and the fractal dimension increases by a maximum of 11.7%. As the shear rate increases, the minimum edge distance of water droplets increases by up to 27.9%, the specific surface area (SA) increases by up to 10.1%, and the fractal dimension decreases by up to 8.5%. Additionally, an analysis is conducted on the collision aggregation behavior of water droplets in shear flow field based on population balance theory.

Study on Wax Deposition Law in Daqing Gulong Shale Oil

Daqing Gulong shale oil exhibits elevated wax content, a high wax precipitation point, and a high freezing point. However, its oil density and viscosity are relatively low, making it susceptible to wax crystal precipitation. The risk of pipeline clogging is heightened in lower ambient temperatures, posing a hazard to the safe production of shale oil. This study focuses on testing the fundamental physical properties of crude oil. The wax deposition flow loop was employed to replicate wax deposition in extracted fluids under actual high-flow gas-liquid conditions within a pipeline. The deposition patterns were determined based on the experimental findings. The results indicate that, irrespective of whether in single-phase, gas-liquid two-phase, or oil-gas-water three-phase conditions, the deposition mass rises with decreasing oil temperature. Furthermore, the deposition mass rises with an increased temperature difference between the oil and the pipeline wall. Conversely, the deposition mass declines with an increased gas-liquid ratio, and the deposition thickness declines with elevated water content. The observed deposition patterns highlight the significant influence of molecular diffusion and the impact of gas phase shear. These experimental findings offer valuable references and insights for the transportation of Daqing shale oil through pipelines.

Chemical compositions and cryo-adhesive probing of the epicuticular wax crystals on fruit surface of wax gourd (Benincasa hispida)

Surface wax crystals play important roles in protecting plants from pest and disease invasions, and UV irradiation. The wax crystals are less probed individually from the fruit surfaces. Herein the morphologies, chemicals and an efficient method to sample the wax blooms of white wax gourd were addressed. Various crystalloids such as rodlets, platelets, fragments, and granules were observed, which stacked as fine wax film covering on wax gourd fruit surface. The wax blooms were effectively removed by cryo-adhesive after consecutive manipulating set by a high-end device with cylinders. Wax crystals were dominated by triterpenols and triterpenol acetates over 61 % of total crystals, followed by vey-long-chain aliphatics. Accordingly, the high-end device with cryo-adhesive provides an efficient approach to selectively probe the wax crystals from those fruits covering wax blooms. The elucidation of morphologies and chemical compositions of wax crystals may help to better understand their regulations on fruit quality traits.

Effects of solvent composition and test temperature on the stability of water-in-model waxy crude oil emulsions

In this article, we investigated the influence of solvent composition and test temperature on the stability of the water-in-oil model emulsions through asphaltene dispersion stability, wax precipitation characteristics, rheology, interfacial film characteristics measurements of diluted model oil-simulated formation water, emulsion stability, microscopic observations, and molecular dynamics simulation. Specifically, we examined the stability of crude oil emulsions at 15° below and 30 above WAT using model oils containing 0.5 wt% asphaltenes and 10 wt% paraffin wax having varying solvent compositions. We observed that increasing the amount of liquid paraffin in the solvents led to smaller changes in the WAT, a reduction in the cumulative wax crystal at −20 °C, and a change in the form of wax crystals from fine particles to larger agglomerated wax crystals. However, the asphaltenes dispersion stability decreased along with it, rheology continued to improve. Meanwhile, we innovatively validated this experimental result using molecular dynamics simulations. Test temperature significantly affects emulsion stability. At 30 °C, increasing the percentage of liquid paraffin reduces interfacial tension, increases the dilatational modulus, and enhances the durability of the interfacial film. This contributes to form small droplets and increases emulsion stability. At 15 °C, increasing the liquid paraffin percentage promoted the development of a more structured wax crystals network, which significantly enhances emulsion stability by binding water droplets. Additionally, we observed that a wax crystal interfacial film could be developed from the wax crystals on the surface of emulsified drops, which improves the emulsion stability and interfacial film strength. Based on our findings, we innovatively present an influencing mechanism model of solvent composition on the synergistic stabilization of model oil emulsion using asphaltenes and paraffin wax.