Freezing is delayed by the interference between the two liquids. This prevents engine damage. Always mix it with distilled water. And the way you do that is before you pour anything back into the cooling system or put it in at any time, you mix coolant and distilled water fifty-fifty, then you put the mix in.
Ethylene glycol is a high-production-volume chemical; it breaks down in air in about 10 days and in water or soil in a few weeks. Names ——————- Solubility in water Solubility log P Vapor pressure. Pros of Using Water Instead of Antifreeze In an emergency, it is still better to put water in your radiator than driving without ANY kind of liquid, even it is better than driving with very low levels of it.
The engine would overheat in this situation, and the consequence would be huge damage to many car parts. Antifreeze lowers the freezing point of any liquid to which it is added by preventing ice crystals from forming properly. Propylene glycol is completely soluble in water and it has the feature of dissolving many organic compounds such as fragrances, essential oils and resins and in addition, it has extremely low toxicity and is virtually harmless to the human body.
Ethylene glycol is completely miscible with water in all proportions as the commenters point out. Therefore, once mixed, the glycol will not separate from the water, ever.
The only exception is if it gets so cold the mixture starts to freeze. Your email address will not be published. Save my name, email, and website in this browser for the next time I comment. Skip to content 1 Answer. Additional Questions Does propylene glycol absorb water? How do you dissolve polyethylene glycol? These metrics are regularly updated to reflect usage leading up to the last few days.
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Cite this: Ind. Article Views Altmetric -. For instance, an insufficient reaction temperature could not effectively extract lignin from biomass, while a severe temperature significantly modified the intact lignin linkages. It is necessary to understand the effects of each parameter on lignin recovery, and further optimization is needed to develop a sustainable lignin fractionation process. Density functional theory DFT is used to calculate bond lengths and interaction energies in lignin—EG—water mixtures to better understand mechanistic interactions.
To achieve these aims, EG-assisted fractionation was conducted on softwood and recovered lignin was characterized. EG has relatively high lignin solubility compared to other organic solvents; 22 thus, it can facilitate effective biomass fractionation and recover a relatively substantial amount of lignin. On the other hand, the minimum lignin recovery was 0. Significantly, different lignin recoveries were observed between experiments depending on the water contents under the same reaction temperatures and the same sulfuric acid contents.
A lower water content resulted in a higher lignin recovery because more lignin is extracted from biomass by EG. Sulfuric acid loading affected the lignin recovery because it catalyzed the hydrolysis reaction of aryl—ether linkages and made fragmented lignin soluble in EG.
It is speculated that this higher lignin recovery is attributed to using an EG—water mixture with a very low water content and a specific type of biomass. Generally, it is easier to separate biomass components from herbaceous biomass compared to woody biomass due to woody biomass having higher lignin content and more rigid structures. The structural information of the recovered lignins was studied using NMR analysis. This observation also suggests that the combined effect of sulfuric acid and temperature on the quality of recovered lignin is much more significant than that of the individual parameters.
These observations indicate that the presence of sulfuric acid significantly affects the cleavage of major lignin linkages to a greater extent than reaction temperature. These results indicate that an acidic environment promoted lignin condensation reactions by forming reactive benzyl carbocations, 30 which resulted in condensed aromatics. It was also noted that the softwood lignin was more susceptible to condensation reactions because guaiacyl units have a large amount of unsubstituted aromatic carbons at the C5 position.
Molecular weights and polydispersity index values for the three recovered lignin samples from EG-assisted fractionation along with milled wood lignin MWL extracted from the raw material are presented in Table 1.
These results align with NMR results; the addition of acid during the biomass fractionation effectively catalyzes the cleavage of aryl—ether bonds, resulting in the production of lignin fragments and a subsequently high lignin recovery.
The R 2 value of the model is 0. Table 2 demonstrates the use of analysis of variance ANOVA to determine the significance of the models. According to Table 2 , the probability of obtaining an F -value greater than the calculated one is less than 0. As a result, there is sufficient evidence that means of the factor levels are not the same and that there are interactions between factors A and B , factors A and C , and factors B and C.
It proceeds that all individual parameters and their interactions have significant effects on lignin recovery. To determine the significance of each coefficient in Equation 5 , a statistical t -test is employed for each parameter.
The t -test results show whether main effects and interactions effects are significant on lignin recovery. According to Table 3 , all parameters and interactions are significant because their p -values are all less than 0. Equation 5 is used as a formula to predict lignin recovery values for the surface plots. As expected, high lignin recovery is associated with low water content, high reaction temperature, and high sulfuric acid content.
Furthermore, from plots A and B, the interactive effects of the water content and temperature as well as the water content and sulfuric acid content on lignin recovery were similar. Temperature and sulfuric acid content have a similarly lesser effect on lignin recovery than that of the water content.
This trend is further demonstrated in plot C, where lignin recovery increases at a similar rate with respect to sulfuric acid content and temperature. It is noted that there are only two levels at each factor in this design. More levels at each factor achieve a broader range of values for an improved design. Surface plots of lignin recovery vs different pairs of parameters: A water content and temperature; B water content and sulfuric acid content; C sulfuric acid content and temperature.
While it is widely known that EG is highly soluble in water, 32 , 33 the effect of adding water to organic solvents on lignin recovery has seldom been explored. As a result, an experiment investigating the solubility of lignin in various EG—water mixtures was conducted. Organosolv lignin dissolved in water forms a slightly cloudy yellow solution, while organosolv lignin dissolved in EG forms a transparent dark brown solution.
Qualitative observations of organosolv lignin dissolved in EG—water mixtures with varying water contents from 0 to A.
Quantitative observations in exploring the effect of the water content on normalized absorbance readings B. Quantitative data of the experiment investigating lignin solubility supports the qualitative data in that a smaller water content results in greater lignin solubility. To make sense of the absorbance readings collected from the experiment, the highest absorbance reading was normalized to a value of 1; all other absorbance readings were taken relative to that value.
This suggests that the solubility of lignin in EG—water mixtures is significantly lower at greater water contents. Qualitative and quantitative results support the hypothesis that an increased water proportion in an EG—water solvent mixture leads to a lower lignin recovery because of the relatively low lignin solubility during fractionation.
This could be attributed to two reasons or a combination of the reasons: a hydrophobicity of lignin or b EG—water hydrogen bonds. It is also important to note that these reasons do not conflict with each other but can rather be two valid reasons for decreasing lignin solubilities as the water content increases. In a similar way that water is used to precipitate lignin out during the lignin precipitation stage of the fractionation experiments, the addition of water to EG in the lignin solubility experiments could simply result in less lignin dissolving in the solvent mixture.
Such hydrophobic interactions between lignin and water could be a reason why an increasing water content would result in decreasing lignin recovery. However, such a speculation merits more evidence. Interactions between a lignin dimeric compound, an EG molecule, and a water molecule were investigated using a constructed DFT model.
Hydrogen bond lengths between the lignin dimer and EG are consistently longer in mixtures with water. For instance, hydrogen bond a has a length of 1. This implies that the addition of water weakens the hydrogen bonds between the lignin dimer and EG. Because hydrogen bonds between the hydroxyl groups in EG and lignin contribute to the lignin dissolution in EG, 22 hydrogen bond lengths from the DFT model suggest that the addition of water in organic solvents used for fractionation decrease lignin recovery.
The following pairs of hydrogen bonds represent the bonds between the same hydrogen atom and oxygen atom: bonds a and d , bonds b and e , and bonds c and f. Hydrogen bond lengths are as follows: 1. Studies reporting strong hydrogen bonding interactions between the hydroxyl groups of water and EG support the DFT model. At a higher water content, the small water clusters that could surround the hydroxyl groups of EG molecules reduce the chances of hydrogen bond formation between lignin and EG.
In addition to hydrogen bonding, interaction energies can be analyzed to develop a better understanding of interactions between lignin, EG, and water.
A study on energy decomposition analysis shows that the interaction energy between EG and water increases each time a water molecule is added to the same number of molecules of EG. These results may indicate that the water molecules form stable structures with EG molecules, leading to fewer interactions between lignin molecules and EG molecules.
Although the experiment conducted on lignin solubility and the constructed DFT model provides mechanistic insights on EG—lignin interactions to understand the effect of the water content on lignin recovery, there are several limits to the DFT model. Conclusions drawn from the simple model can develop, rather than ensure, an understanding of interactions between EG, water, and lignin.
Besides the lignin model compound used in the study, there are other compounds in lignin that interact with EG and water. The use of the sulfuric acid catalyst at a high temperature during the fractionation cleaved most aryl—ether linkages in lignin, which are important to preserve for lignin valorization.
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