Calcium hydroxide as a highly alkaline pH standard

Bates, Roger G.; Bower, V.E.; Smith, Edgar

doi:10.6028/jres.056.040

Cited by 51 publications

(31 citation statements)

References 8 publications

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“…This indicates that dissolved Ca ions were mainly supplied from the portlandite in the steel slags for the formation of C-S-H. Because portlandite easily reaches saturation in aqueous solutions at ambient temperatures [21], and factor (a) here would be the limiting factor for C-S-H formation when there are limits to the portlandite quantity in the steel slags. The XRD analyses of the mixtures made with slag 2 show that the portlandite supply was much lower than in the mixtures with slag 1 (Figures 8 and 9), indicating that the content of portlandite in the steel slags, is an important factor controlling the formation of C-S-H.…”

Section: Factor (A): Calcium Ion Supply As a Factor In C-s-h Formationmentioning

confidence: 99%

“…However, an additional factor to consider is that the pH of the pore water may be buffered to values of weak bases by the humic acid as they are weak acids [25]. The pH of the pore water of mixtures 1A, 1B, 1C, and 1D were maintained above 12 within the first day of curing, which can be explained by the dissolution equilibrium of portlandite, that establishes pH of 12.45 [21]. The effect of pH buffering by humic acids were not observed in the mixtures where pH was measured in this study.…”

Section: Factor (B): Ph Of Pore Water In the Mixtures As A Factor In mentioning

confidence: 99%

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Key Factors Affecting Strength Development of Steel Slag-Dredged Soil Mixtures

et al. 2018

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Some of the steel slag from ironworks and dredged soils from marine and waterfront engineering work are partially treated as waste. However, a mixture of these two kinds of waste has the potential to be used as construction materials when mixed, due to chemical reactions forming secondary phases. Utilizing waste of such kind as a resource will help to improve sustainability in society by reducing waste and replacing virgin resources such as cement. Recently, it was reported that mixtures of steel slag and dredged soil hardens under specific conditions. The phase compositions of dredged soils and steel slags vary depending on the quantity of each component, which results in unpredictable strength development of mixtures. The effect of the variations in the components of steel slags and dredged soils on strength development of the mixtures is not yet clear, limiting the utilization of both materials. Understanding the hardening mechanisms of the mixtures will enable the prediction of strength development. Focusing on the variations in the components in steel slags and, especially of dredged soils, this study aims to identify the components in both materials that affect the secondary phase formation that are responsible for strength development. We found support for suggestions that calcium silicate hydrate, C-S-H, is one of the secondary phases responsible for the strength development of the mixtures. From a comparison of two kinds of steel slags and various dredged soils, the amount of portlandite in the steel slags and the amount of amorphous silica in the dredged soils are suggested as a couple of the key components of starting materials involved in the C-S-H formation.

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Section: Factor (A): Calcium Ion Supply As a Factor In C-s-h Formationmentioning

confidence: 99%

Section: Factor (B): Ph Of Pore Water In the Mixtures As A Factor In mentioning

confidence: 99%

Key Factors Affecting Strength Development of Steel Slag-Dredged Soil Mixtures

et al. 2018

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“…However, Ca(OH) 2 extraction leads to relatively low protein yields . This low yield might be due to the low solubility of Ca(OH) 2 in water, which results in a less alkaline solution compared to NaOH and KOH. Besides, calcium atoms contain two valence electrons through which calcium cations can function as bridges between different chelating molecules .…”

Section: Introductionmentioning

confidence: 99%

Sustainable scenarios for alkaline protein extraction from leafy biomass using green tea residue as a model material

Zhang

Slegers

Wisse

et al. 2018

Biofuels Bioprod Bioref

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Leaf protein can be extracted cost‐efficiently using 0.1 mol dm−3 NaOH, but this process is less sustainable due to the generation of large amounts of sodium salts. KOH or Ca(OH)2 are considered as replacements for NaOH, as these salts can be reused. This work evaluates the economic and environmental sustainability of weak alkaline pectin extraction followed by KOH enhanced protein extraction, and Viscozyme® L‐aided pectin extraction followed by Ca(OH)2 enhanced protein extraction. The evaluations are made for green tea residue and are compared to related processes using NaOH. The predicted profits using KOH are comparable to those using NaOH. Environmental sustainability improves for all impact categories in the case of KOH extraction. Further environmental benefits are obtained by substituting conventional K fertilizer with the K‐rich salty waste water from the extraction process. The profits of the process using Ca(OH)2 are highly dependent on the extraction yield of the protein product. Protein extraction yields using Ca(OH)2 need to be higher than 70% to be more profitable than the same process with NaOH. The environmental benefits of Ca(OH)2 extraction include the absence of salty waste water and the net production of heat. This is accompanied by increased electricity consumption. Thus, the impact categories of climate change, fossil and water depletion, and particulate matter formation worsen. Photochemical oxidant formations remain the same, while the other impacts improve. This work has shown the potential and bottlenecks of NaOH, KOH and Ca(OH)2 protein extraction on different types of biomass in terms of environmental and economic sustainability. © 2018 Society of Chemical Industry and John Wiley & Sons, Ltd

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“…The coefficients of eq. [4] for water were obtained by using the data of Bates et al (29) and are listed in Table 3 of NaN03 , and are listed in Table 3. The estimated uncertainties (30) in …”

Section: Methodsmentioning

confidence: 99%

Ion–ion–solvent interactions in aqueous ionic cosolvent systems. I. Transfer thermodynamics of hydrogen chloride in aqueous sodium nitrate solutions from emf measurements

Rudra¹,

Talukdar²,

Chakravarti³

et al. 1986

Can. J. Chem.

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Standard potentials (EO) of the Ag-AgCl electrode have been determined in 1. 2, and 4 rn NaN03 + water mixtures at five equidistant temperatures ranging from 15-35°C from the emf measurements of the cell: Pt, H2 (g, 1 atm)/HCl ( m ) NaN03 + water/AgCl-Ag. These values have been used to evaluate the trarisfer energetics (AG?, TAG, and A@) accompanying the transfer of 1 mole of HCl from the standard state in water to the standard state in each of the NaN03 + water mixtures. Transfer free energies AG: of HCl and that of the individual ions obtained from a separate study, and those obtained after correcting the "cavity effect" and Born-type electrostatic effect, as estimated tentatively by the scaled-particle theory (SPT) and simple Born equation respectively, have been discussed in the light of ion-ion-solvent interactions. The observed TAG-composition profile as well as that obtained after correcting for the "cavity effect" were examined in the light of semiquantitative theory proposed by Kundu et al. earlier and are found to substantiate this theory.

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Calcium hydroxide as a highly alkaline pH standard

Cited by 51 publications

References 8 publications

Key Factors Affecting Strength Development of Steel Slag-Dredged Soil Mixtures

Key Factors Affecting Strength Development of Steel Slag-Dredged Soil Mixtures

Sustainable scenarios for alkaline protein extraction from leafy biomass using green tea residue as a model material

Ion–ion–solvent interactions in aqueous ionic cosolvent systems. I. Transfer thermodynamics of hydrogen chloride in aqueous sodium nitrate solutions from emf measurements

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