Luuk K. Koopal is a Physical and Colloid Chemist with research interests in fundamental and applied aspects of interfacial and environmental science. He worked at Wageningen University (and Research), NL, as professor and has held several invited professorships in other countries. Since 2007 he is emeritus and Guest Professor at the College of Resources and Environment, Huazhong Agricultural University, Wuhan, P.R. China. He has contributed for many years to the ‘International Union of Pure and Applied Chemistry’ (IUPAC) and was elected Chairman of the ‘Commission on Surface and Colloid Chemistry, including Catalysis’. He founded the very successful International ‘Interfaces Against Pollution’ (IAP) conferences.
A review is given of the physico-chemical principles of cleaning. Particular attention is paid to... more A review is given of the physico-chemical principles of cleaning. Particular attention is paid to: particle and/or droplet adhesion and removal, rupture and removal of thin oily films, emulsification of thick oily films, uptake of substances in surfactant micelles by solubilisation and causes of re-deposition, The role of surface-active agents in facilitating the removal and in enhancing the stability of the dispersed soil is emphasised. Hydrodynamic affects are briefly explained. The adsorption behaviour of the different types of surface-active substances and the working mechanisms of Ca-complexing agents are discussed.
the kaolinite siloxane plates is masked by the larger entropy loss of adsorption on the hydrophil... more the kaolinite siloxane plates is masked by the larger entropy loss of adsorption on the hydrophilic surface. The fractions of JGHA with molar mass > ~12.9 kDa (1 Da = 1 g mol-1) were adsorbed selectively by KGM, whereas the fractions < ~12.9 kDa were selectively adsorbed by KGA. High molar mass and hydrophobic fractions adsorb selectively on the kaolinite siloxane plates, whereas low molar mass fractions with hydrophilic groups adsorb selectively on goethite and the kaolinite edges.
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 1999
In this study the froth flotation technique was applied to clean a sandy soil sludge contaminated... more In this study the froth flotation technique was applied to clean a sandy soil sludge contaminated with soot particles containing a large amount of polynuclear aromatic hydrocarbons (PAHs). To obtain insight into the flotation process, contact angles on soot pellets and silica plates were determined in both the absence and presence of several collectors and the results were compared with the flotation recovery of soot (90-200 mm) and silica (90-200 mm) from suspensions of the pure materials using a modified Hallimond tube. Aerophine, dodecylpyridinium chloride and three different oils were used as collectors. Adding a collector increased the contact angles on soot particles from 89°to at least 100°a nd increased the flotation recovery from 56% to 100%. However, the contact angle and the flotation recovery of silica are also enhanced under optimal conditions for soot flotation. A semi-continuous dissolved air flotation apparatus was used for the practical flotation experiments. The contaminated sludge fraction contained silica particles of 20 to 125 mm and soot particles of 20 to 500 mm. The best flotation results were obtained when a combination of emulsified diesel oil as collector and emulsified Montanol (a mixture of higher alcohols) as frother was used. Under optimal conditions 95% of the PAHs were removed and concentrated in only 2.5% of the total mass of the sludge.
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 1993
A comparison of experimental data with self-consistent field lattice calculations and molecular d... more A comparison of experimental data with self-consistent field lattice calculations and molecular dynamics simulations has shown that the latter two approaches are able to predict in a qualitative sense the relation between the structure of a surfactant and its interfacial tension at an oil/water interface. Micelles can also be observed in the simulations and in the self-consistent field calculations. Advantages and disadvantages of the simulations and the self-consistent field calculations are discussed and it is concluded that current theoretical models provide reasonable descriptions of complex colloidal systems.
Compression refining is one of the new technologies being developed in The Netherlands to minimis... more Compression refining is one of the new technologies being developed in The Netherlands to minimise fibre damage and thereby prolong the fibre recycling loop. The new developments, which are designed to counteract the degrading effects of processing on fibre, fall into two main categories: ○ preventive technologies such as compression refining and ○ restorative technologies -to upgrade fibres which have been degraded during the papermaking, converting and recycling processes. The development work follows a research project on Fibre raw material technology for sustainable production of paper and board. The quality changes during processing were assessed, and it was concluded that the development of new technologies should focus on: ○ fibre flexibility and relative bonded area ○ fines content and morphology ○ ash content ○ surface charge During mechanical processing there are changes in fibre morphology, including internal fibrillation and external fibrillation. While internal fibrilla...
A review is given of the physico-chemical principles of cleaning. Particular attention is paid to... more A review is given of the physico-chemical principles of cleaning. Particular attention is paid to: particle and/or droplet adhesion and removal, rupture and removal of thin oily films, emulsification of thick oily films, uptake of substances in surfactant micelles by solubilisation and causes of re-deposition, The role of surface-active agents in facilitating the removal and in enhancing the stability of the dispersed soil is emphasised. Hydrodynamic affects are briefly explained. The adsorption behaviour of the different types of surface-active substances and the working mechanisms of Ca-complexing agents are discussed.
the kaolinite siloxane plates is masked by the larger entropy loss of adsorption on the hydrophil... more the kaolinite siloxane plates is masked by the larger entropy loss of adsorption on the hydrophilic surface. The fractions of JGHA with molar mass > ~12.9 kDa (1 Da = 1 g mol-1) were adsorbed selectively by KGM, whereas the fractions < ~12.9 kDa were selectively adsorbed by KGA. High molar mass and hydrophobic fractions adsorb selectively on the kaolinite siloxane plates, whereas low molar mass fractions with hydrophilic groups adsorb selectively on goethite and the kaolinite edges.
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 1999
In this study the froth flotation technique was applied to clean a sandy soil sludge contaminated... more In this study the froth flotation technique was applied to clean a sandy soil sludge contaminated with soot particles containing a large amount of polynuclear aromatic hydrocarbons (PAHs). To obtain insight into the flotation process, contact angles on soot pellets and silica plates were determined in both the absence and presence of several collectors and the results were compared with the flotation recovery of soot (90-200 mm) and silica (90-200 mm) from suspensions of the pure materials using a modified Hallimond tube. Aerophine, dodecylpyridinium chloride and three different oils were used as collectors. Adding a collector increased the contact angles on soot particles from 89°to at least 100°a nd increased the flotation recovery from 56% to 100%. However, the contact angle and the flotation recovery of silica are also enhanced under optimal conditions for soot flotation. A semi-continuous dissolved air flotation apparatus was used for the practical flotation experiments. The contaminated sludge fraction contained silica particles of 20 to 125 mm and soot particles of 20 to 500 mm. The best flotation results were obtained when a combination of emulsified diesel oil as collector and emulsified Montanol (a mixture of higher alcohols) as frother was used. Under optimal conditions 95% of the PAHs were removed and concentrated in only 2.5% of the total mass of the sludge.
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 1993
A comparison of experimental data with self-consistent field lattice calculations and molecular d... more A comparison of experimental data with self-consistent field lattice calculations and molecular dynamics simulations has shown that the latter two approaches are able to predict in a qualitative sense the relation between the structure of a surfactant and its interfacial tension at an oil/water interface. Micelles can also be observed in the simulations and in the self-consistent field calculations. Advantages and disadvantages of the simulations and the self-consistent field calculations are discussed and it is concluded that current theoretical models provide reasonable descriptions of complex colloidal systems.
Compression refining is one of the new technologies being developed in The Netherlands to minimis... more Compression refining is one of the new technologies being developed in The Netherlands to minimise fibre damage and thereby prolong the fibre recycling loop. The new developments, which are designed to counteract the degrading effects of processing on fibre, fall into two main categories: ○ preventive technologies such as compression refining and ○ restorative technologies -to upgrade fibres which have been degraded during the papermaking, converting and recycling processes. The development work follows a research project on Fibre raw material technology for sustainable production of paper and board. The quality changes during processing were assessed, and it was concluded that the development of new technologies should focus on: ○ fibre flexibility and relative bonded area ○ fines content and morphology ○ ash content ○ surface charge During mechanical processing there are changes in fibre morphology, including internal fibrillation and external fibrillation. While internal fibrilla...
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