Dissolution Modeling and Experimental Measurement of CaS‐H<sub>2</sub>O Binary System

Zekker, Ivar; Tenno, Toomas; Selberg, Aare; Uiga, Kalev

doi:10.1002/cjoc.201180399

Cited by 11 publications

(14 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It occupies approximately 50% of the paste volume and responds to nearly all the engineering properties of the cement paste [18]. Related equilibrium studies have been performed assessing the effect of pH and other factors on the material performance [19][20][21].…”

Section: Discussionmentioning

confidence: 99%

Relationship between Phase Composition and Mechanical Properties of Peat Soils Stabilized Using Oil Shale Ash and Pozzolanic Additive

Rikmann

Zekker

Teppand

et al. 2021

Water

Self Cite

View full text Add to dashboard Cite

Construction of road embankments in peatlands commonly involves replacement of the peat with a fill-up soil of an adequate load-bearing capacity. This usually requires a lowering of the water level, turning a peatland from a carbon sink to a source of greenhouse gases. Thus, alternatives are sought that are less costly in both economic and ecological terms. Mass-stabilization technology can provide a cheap substitute for Portland cement. Calcareous ashes (waste materials), supplemented with pozzolanic and alkali additives to facilitate and accelerate the setting and hardening processes, are attractive alternatives to soil excavation or replacement techniques. Silica fume and waterglass were used as pozzolanic agents and KOH as a soil-alkalizing agent. X-ray fluorescence (XRF), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) analyses and stress–strain tests were performed for the hardened samples. Crystallization of alkali feldspars was observed in all test samples. Comparable hardening of peat soil was achieved for both ashes. It was shown that the ashes of Estonian kukersite (oil shale) from both pulverized firing and a circulating fluidized bed incineration process (produced in energy sector as quantitatively major solid waste in Estonia) can be used as binding agents for peat stabilization, even without the addition of Portland cement. Hardened peat soil samples behaved as a ductile material, and the cellulose fibers naturally present in peat gave the peat–ash composite plasticity, acting mechanically in the same way as the steel or glass fiber in ordinary reinforced concrete. The effect of peat fiber reinforcement was higher in cases of higher load and displacement of the composite, making the material usable in ecological constructions.

show abstract

Section: Discussionmentioning

confidence: 99%

Relationship between Phase Composition and Mechanical Properties of Peat Soils Stabilized Using Oil Shale Ash and Pozzolanic Additive

Rikmann

Zekker

Teppand

et al. 2021

Water

Self Cite

View full text Add to dashboard Cite

show abstract

“…The negative value of ∆H • indicates the exothermic nature of the process and the positive value of entropy shows the increase in randomness at the dye/adsorbent interfaces and the feasibility of the process [49]. Previous researches have been performed assessing the effect of pH and other factors on the material performance, which could be done similarly in future studies [50][51][52]. In order to determine the reusability of the Pd-Ni/AC-CeO 2 adsorbent, the nanoparticles were used several times and the removal efficiency was monitored.…”

Section: Thermodynamic Studymentioning

confidence: 99%

Synthesis and Characterization of Pd-Ni Bimetallic Nanoparticles as Efficient Adsorbent for the Removal of Acid Orange 8 Present in Wastewater

Umar

Khan

Alam

et al. 2021

Water

Self Cite

View full text Add to dashboard Cite

In this study palladium-nickel (Pd-Ni) nanoparticles supported on carbon and cerium oxide (Pd-Ni/AC-CeO2) were synthesized by a transfer phase method and characterized by scanning electronic microscopy (SEM), X-ray diffraction (XRD), and energy-dispersive X-ray spectroscopy (EDX). The XRD and SEM data concluded the presence of alloy formation between Pd and Ni. The synthesized particles were used as an adsorbent for removal of azo dye acid orange-8 (AO-8) from water and were found to be effective in removal (over 90% removal efficiency) of the selected dye. Different kinetics and equilibrium models were applied to calculate the adsorption parameters. The most suitable model that best fitted the equilibrium data was the Langmuir model and maximum adsorption capacities were 666.6, 714 and 769 mg/g at 293, 313 and 333 K, respectively, with R2 values closed to 1 while in the case of the kinetics data the best fit was obtained with a pseudo-second order kinetics model with a high R2 value. Furthermore, the adsorption thermodynamics parameters such as free energy, enthalpy, and entropy were calculated and the adsorption process was to found be exothermic with a value of ΔH° (−7.593 kJ mol−1), spontaneous as ΔG° values were negative (−18.7327, −19.4870, and −20.584 kJ/mol at 293, 313 and 333 K, respectively). A positive entropy change ΔS° with a value of 0.0384 kJ /mol K indicates increased disorder at the solid–solution interface during the adsorption process. An attempt was made to recycle the Pd-Ni/AC-CeO2 with suitable solvents and the recycled adsorbent was reused for 6 cycles with AO-8 removal efficiency up to 80%. Based on findings of the study, the synthesized adsorbent could effectively be used for the removal of other pollutants from wastewater, however, further studies are needed to prove the mechanisms.

show abstract

“…V CH = 33 cm 3 /mol is used for the molar volume of portlandite. For CaS, the molar volume V CaS is chosen as 28 cm 3 /mol (Wiberg, 2001;Zekker et al, 2011).…”

Section: Porosity Change During H 2 S Attackmentioning

confidence: 99%

Degradation modeling of concrete submitted to biogenic acid attack

Yuan

Dangla

Chatellier³

et al. 2015

Cement and Concrete Research

View full text Add to dashboard Cite

Biodeterioration of concrete,which is very common in sewer system, results in significant structure degradation. The process can be described by the 3 following steps: Concrete surface neutralization providing appropriate environment for sulfur oxidizing bacteria (SOB) to grow, sulfuric acid (H2SO4) production by SOB on concrete surface and chemical reaction between H2SO4 and cement hydration products. A reactive transport model is proposed to simulate the whole biodeterioration processes of concrete in contact with H2S gas and SOB. This model aims at solving simultaneously transport and biochemistry/chemistry in biofilm and concrete by a global coupled approach. To simulate the neutralization process, the absorption of H2S gas, the dissolution of portlandite (CH), the decalcification of calcium silicate hydrates (C-S-H) and the precipitation of calcium sulfide (CaS) are considered. To obtain the amount of biogenic acid, the production rate of H2SO4 by SOB is calculated via a set of simplified models governed by pH. Coupling with the modeling of H2SO4 degradation process, the biodeterioration depth and the solid composition evolution could be predicted. A laboratory experiment reported in literature is simulated and the simulation results are compared with experimental results

show abstract

Dissolution Modeling and Experimental Measurement of CaS‐H₂O Binary System

Abstract: CaS formed during the retorting process of oil shale has a hazardous influence on surface water quality. Interaction of retorted oil shale with water generates highly alkaline leachate with a high content of sulfur due to the CaS (mo•L -1 ) 2 at a temperature of 25 ℃.

Cited by 11 publications

References 32 publications

Relationship between Phase Composition and Mechanical Properties of Peat Soils Stabilized Using Oil Shale Ash and Pozzolanic Additive

Relationship between Phase Composition and Mechanical Properties of Peat Soils Stabilized Using Oil Shale Ash and Pozzolanic Additive

Synthesis and Characterization of Pd-Ni Bimetallic Nanoparticles as Efficient Adsorbent for the Removal of Acid Orange 8 Present in Wastewater

Degradation modeling of concrete submitted to biogenic acid attack

Contact Info

Product

Resources

About

Dissolution Modeling and Experimental Measurement of CaS‐H2O Binary System

Abstract: CaS formed during the retorting process of oil shale has a hazardous influence on surface water quality. Interaction of retorted oil shale with water generates highly alkaline leachate with a high content of sulfur due to the CaS (mo•L -1 ) 2 at a temperature of 25 ℃.

Cited by 11 publications

References 32 publications

Relationship between Phase Composition and Mechanical Properties of Peat Soils Stabilized Using Oil Shale Ash and Pozzolanic Additive

Relationship between Phase Composition and Mechanical Properties of Peat Soils Stabilized Using Oil Shale Ash and Pozzolanic Additive

Synthesis and Characterization of Pd-Ni Bimetallic Nanoparticles as Efficient Adsorbent for the Removal of Acid Orange 8 Present in Wastewater

Degradation modeling of concrete submitted to biogenic acid attack

Contact Info

Product

Resources

About

Dissolution Modeling and Experimental Measurement of CaS‐H₂O Binary System