La presente communication demontre la possibilite d'utiliser la microscopie electronique a ba... more La presente communication demontre la possibilite d'utiliser la microscopie electronique a balayage (MEB) et l'analyse par rayons X a dispersion d'energie (EDAX) pour quantifier la distribution des mineraux en direction Z dans le papier. Une section transversale du papier est examinee a l'aide de la MEB et une section couvrant l'epaisseur du papier est soumise a une analyse EDAX afin de determiner la teneur en mineraux dans la direction de l'epaisseur du papier. Cette surface est encore une fois divisee en cinq zones, afin d'en determiner la teneur en mineraux. Cette methode devrait permettre aux fabricants de papier de produire une structure de feuille destinee a diverses utilisations finales.
The formation of calcium-phosphorus (Ca-P) containing overgrowths on the surface of ground calciu... more The formation of calcium-phosphorus (Ca-P) containing overgrowths on the surface of ground calcium carbonate (GCC) treated with phosphoric acid was studied. During GCC dissolution in water containing H 3 PO 4 , the rate of phosphorus precipitation gradually increased and reached equilibrium in 15 hours. Energy-dispersive X-ray (EDX) analysis of the GCC treated with H 3 PO 4 showed that the kinetics of formation of Ca-P overgrowths on the GCC surface follows a profile similar to phosphorus precipitation. X-ray photoelectron spectroscopy and EDX show that increasing H 3 PO 4 concentration increases the formation of Ca-P overgrowths on GCC. Scanning electron microscopic scans revealed a different morphology on the GCC surface because of the overgrowths, which are believed to inhibit GCC dissolution. When GCC was added to a pulp suspension containing H 3 PO 4 , the pH rise was suppressed. Finally, handsheets were made and the brightness and scattering coefficient were found to slightly improve with increasing H 3 PO 4 concentration.
The inhibition of the dissolution of papermaking grade precipitated calcium carbonate filler with... more The inhibition of the dissolution of papermaking grade precipitated calcium carbonate filler with sodium oxalate and phosphoric acid at pH 7.5 increased with inhibitor concentration. The saturation points for sodium oxalate and and phosphoric acid were 1.0 x 10 -2 mol/L and 0.5 x 10 -3 mol/L. Oxalate ions inhibited the calcium carbamate dissolution in the entire range of pH studied. The inhibition was greater at lower pH. At an inhibitor concentration of 0.0014 mol/L. and pH 7.5, the most effective chemical was phosphoric acid. The solubility of calcium ion was 80% lower than that in a solution without inhibitor. The authors also studied the inhibition of calcium carbonate dissolution by phosphoric acid in a CTMP suspension. For each level of precipitated calcium carbonated loading, a saturation point occurred, and the amount of phosphoric acid required to achieve the saturation point increased with the filler loading. Application : phosphoric acid is an efficient inhibitor for the dissolution of precipitated calcium carbonate in water. It has the potential for use in PCC solubility control in papermaking suspension.
Metal ions collectively known in the pulp and paper industry as Non-Process Elements (NPEs) are f... more Metal ions collectively known in the pulp and paper industry as Non-Process Elements (NPEs) are found in kraft pulp suspensions because they enter a kraft mill with wood chips, water and chemicals. Knowledge of the partitioning behaviour of these metal ions between the fibre and the liquor is important for the design of closed-cycle kraft pulp mills. In a pulp suspension, the distribution of metal ions between the fibres and liquor can be modeled using Donnan equilibrium. In this framework, the anionic charge on the fibres is the most critical parameter in determining the distribution of all metal ions at a given pH. The interpretation of potentiometric titration data of ha f t fibres within the Donnan framework provides the necessary charge model.
Abstract A computational methodology for the simultaneous regression of binary vapor—liquid and v... more Abstract A computational methodology for the simultaneous regression of binary vapor—liquid and vapor—liquid—liquid equilibrium data is presented. It is used for the estimation of the interaction parameters in equations of state. An implicit least-squares estimation procedure has been developed which yields the best set of parameter estimates for the equation of state. Subsequently, if the thermodynamic model is capable of representing the data without any systematic deviation, the statistically optimal parameters can be obtained by a proposed implicit maximum likelihood estimation procedure. The key advantage of both the estimation procedures is the absence of any iterative phase equilibrium computations. As a result, the methodology is easily implemented and is computationally very efficient. The application of the method is illustrated with a typical example (hydrogen sulfide—water).
... Titre du document / Document title. The use of a fixative in conjunction with poly(ethylene o... more ... Titre du document / Document title. The use of a fixative in conjunction with poly(ethylene oxide) for enhanced retention. Auteur(s) / Author(s). TRIGYLIDAS Dennis (1) ; ENGLEZOS Peter (2) ;THORBURN Ian (3) ; Affiliation(s) du ou des auteurs / Author(s) Affiliation(s). (1) Dept. ...
... In practice, VLE data are available as sets of isothermal measurements ... The problem of min... more ... In practice, VLE data are available as sets of isothermal measurements ... The problem of minimizing equation (1) subject to constraint (5) is transformed into an unconstrained one by introducing the Lagrange multiplier A. and augmenting the LS objective function S(k) to yield: S5(k ...
La presente communication demontre la possibilite d'utiliser la microscopie electronique a ba... more La presente communication demontre la possibilite d'utiliser la microscopie electronique a balayage (MEB) et l'analyse par rayons X a dispersion d'energie (EDAX) pour quantifier la distribution des mineraux en direction Z dans le papier. Une section transversale du papier est examinee a l'aide de la MEB et une section couvrant l'epaisseur du papier est soumise a une analyse EDAX afin de determiner la teneur en mineraux dans la direction de l'epaisseur du papier. Cette surface est encore une fois divisee en cinq zones, afin d'en determiner la teneur en mineraux. Cette methode devrait permettre aux fabricants de papier de produire une structure de feuille destinee a diverses utilisations finales.
The formation of calcium-phosphorus (Ca-P) containing overgrowths on the surface of ground calciu... more The formation of calcium-phosphorus (Ca-P) containing overgrowths on the surface of ground calcium carbonate (GCC) treated with phosphoric acid was studied. During GCC dissolution in water containing H 3 PO 4 , the rate of phosphorus precipitation gradually increased and reached equilibrium in 15 hours. Energy-dispersive X-ray (EDX) analysis of the GCC treated with H 3 PO 4 showed that the kinetics of formation of Ca-P overgrowths on the GCC surface follows a profile similar to phosphorus precipitation. X-ray photoelectron spectroscopy and EDX show that increasing H 3 PO 4 concentration increases the formation of Ca-P overgrowths on GCC. Scanning electron microscopic scans revealed a different morphology on the GCC surface because of the overgrowths, which are believed to inhibit GCC dissolution. When GCC was added to a pulp suspension containing H 3 PO 4 , the pH rise was suppressed. Finally, handsheets were made and the brightness and scattering coefficient were found to slightly improve with increasing H 3 PO 4 concentration.
The inhibition of the dissolution of papermaking grade precipitated calcium carbonate filler with... more The inhibition of the dissolution of papermaking grade precipitated calcium carbonate filler with sodium oxalate and phosphoric acid at pH 7.5 increased with inhibitor concentration. The saturation points for sodium oxalate and and phosphoric acid were 1.0 x 10 -2 mol/L and 0.5 x 10 -3 mol/L. Oxalate ions inhibited the calcium carbamate dissolution in the entire range of pH studied. The inhibition was greater at lower pH. At an inhibitor concentration of 0.0014 mol/L. and pH 7.5, the most effective chemical was phosphoric acid. The solubility of calcium ion was 80% lower than that in a solution without inhibitor. The authors also studied the inhibition of calcium carbonate dissolution by phosphoric acid in a CTMP suspension. For each level of precipitated calcium carbonated loading, a saturation point occurred, and the amount of phosphoric acid required to achieve the saturation point increased with the filler loading. Application : phosphoric acid is an efficient inhibitor for the dissolution of precipitated calcium carbonate in water. It has the potential for use in PCC solubility control in papermaking suspension.
Metal ions collectively known in the pulp and paper industry as Non-Process Elements (NPEs) are f... more Metal ions collectively known in the pulp and paper industry as Non-Process Elements (NPEs) are found in kraft pulp suspensions because they enter a kraft mill with wood chips, water and chemicals. Knowledge of the partitioning behaviour of these metal ions between the fibre and the liquor is important for the design of closed-cycle kraft pulp mills. In a pulp suspension, the distribution of metal ions between the fibres and liquor can be modeled using Donnan equilibrium. In this framework, the anionic charge on the fibres is the most critical parameter in determining the distribution of all metal ions at a given pH. The interpretation of potentiometric titration data of ha f t fibres within the Donnan framework provides the necessary charge model.
Abstract A computational methodology for the simultaneous regression of binary vapor—liquid and v... more Abstract A computational methodology for the simultaneous regression of binary vapor—liquid and vapor—liquid—liquid equilibrium data is presented. It is used for the estimation of the interaction parameters in equations of state. An implicit least-squares estimation procedure has been developed which yields the best set of parameter estimates for the equation of state. Subsequently, if the thermodynamic model is capable of representing the data without any systematic deviation, the statistically optimal parameters can be obtained by a proposed implicit maximum likelihood estimation procedure. The key advantage of both the estimation procedures is the absence of any iterative phase equilibrium computations. As a result, the methodology is easily implemented and is computationally very efficient. The application of the method is illustrated with a typical example (hydrogen sulfide—water).
... Titre du document / Document title. The use of a fixative in conjunction with poly(ethylene o... more ... Titre du document / Document title. The use of a fixative in conjunction with poly(ethylene oxide) for enhanced retention. Auteur(s) / Author(s). TRIGYLIDAS Dennis (1) ; ENGLEZOS Peter (2) ;THORBURN Ian (3) ; Affiliation(s) du ou des auteurs / Author(s) Affiliation(s). (1) Dept. ...
... In practice, VLE data are available as sets of isothermal measurements ... The problem of min... more ... In practice, VLE data are available as sets of isothermal measurements ... The problem of minimizing equation (1) subject to constraint (5) is transformed into an unconstrained one by introducing the Lagrange multiplier A. and augmenting the LS objective function S(k) to yield: S5(k ...
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