Studying bubble-particle interactions by zeta potential distribution analysis

Over a decade ago, Xu and Masliyah pioneered an approach to characterize the interactions between particles in dynamic environments of multicomponent systems by measuring zeta potential distributions of individual components and their mixtures. Using a Zetaphoremeter, the measured zeta potential distributions of individual components and their mixtures were used to determine the conditions of preferential attachment in multicomponent particle suspensions. The technique has been applied to study the attachment of nano-sized silica and alumina particles to sub-micron size bubbles in solutions with and without the addition of surface active agents (SDS, DAH and DF250). The degree of attachment between gas bubbles and particles is shown to be a function of the interaction energy governed by the dispersion, electrostatic double layer and hydrophobic forces. Under certain chemical conditions, the attachment of nano-particles to sub-micron size bubbles is shown to be enhanced by in-situ gas nucleation induced by hydrodynamic cavitation for the weakly interacting systems, where mixing of the two individual components results in negligible attachment. Preferential interaction in complex tertiary particle systems demonstrated strong attachment between micron-sized alumina and gas bubbles, with little attachment between micron-sized alumina and silica, possibly due to instability of the aggregates in the shear flow environment

Problematic Stabilizing Films in Petroleum Emulsions: Shear Rheological Response of Viscoelastic Asphaltene Films and the Effect on Drop Coalescence

Adsorption of asphaltenes at the water-oil interface contributes to the stability of petroleum emulsions by forming a networked film that can hinder drop-drop coalescence. The interfacial microstructure can either be liquid-like or solid-like, depending on (i) initial bulk concentration of asphaltenes, (ii) interfacial aging time, and (iii) solvent aromaticity. Two techniques--interfacial shear rheology and integrated thin film drainage apparatus--provided equivalent interface aging conditions, enabling direct correlation of the interfacial rheology and droplet stability. The shear rheological properties of the asphaltene film were found to be critical to the stability of contacting drops. With a viscous dominant interfacial microstructure, the coalescence time for two drops in intimate contact was rapid, on the order of seconds. However, as the elastic contribution develops and the film microstructure begins to be dominated by elasticity, the two drops in contact do not coalescence. Such step-change transition in coalescence is thought to be related to the high shear yield stress (~10(4) Pa), which is a function of the film shear yield point and the film thickness (as measured by quartz crystal microbalance), and the increased elastic stiffness of the film that prevents mobility and rupture of the asphaltene film, which when in a solid-like state provides an energy barrier against drop coalescence

Dissipation of Film Drainage Resistance by Hydrophobic Surfaces in Aqueous Solutions

Understanding and minimizing the film drainage resistance (forces) from a moving fluid are of great importance both scientifically and technologically. The direct and accurate measurement of film drainage resistance was made possible by integrating a speaker diaphragm of large displacement range and rapid responses with a sensitive bimorph force sensor and high resolution digital camera. Our study demonstrates that the liquid film drainage resistance can be greatly diminished or accurately controlled by increasing or controlling the hydrophobicity of solid surfaces. The results show that for a given solid surface hydrophobicity, the film drainage resistance at the point where film ruptures increases linearly with increasing bubble approach velocity. The dependence of the film drainage resistance on bubble approach velocity decreases linearly with increasing hydrophobicity of the solid surface. This finding has important implications for biological processes, microfluidic devices, and design of new materials

Dissipation of Film Drainage Resistance by Hydrophobic Surfaces in Aqueous Solutions

Understanding and minimizing the film drainage resistance (forces) from a moving fluid are of great importance both scientifically and technologically. The direct and accurate measurement of film drainage resistance was made possible by integrating a speaker diaphragm of large displacement range and rapid responses with a sensitive bimorph force sensor and high resolution digital camera. Our study demonstrates that the liquid film drainage resistance can be greatly diminished or accurately controlled by increasing or controlling the hydrophobicity of solid surfaces. The results show that for a given solid surface hydrophobicity, the film drainage resistance at the point where film ruptures increases linearly with increasing bubble approach velocity. The dependence of the film drainage resistance on bubble approach velocity decreases linearly with increasing hydrophobicity of the solid surface. This finding has important implications for biological processes, microfluidic devices, and design of new materials

Measurement of Interactions between Solid Particles, Liquid Droplets, and/or Gas Bubbles in a Liquid using an Integrated Thin Film Drainage Apparatus

A novel device was designed to measure drainage dynamics of thin liquid films confined between a solid particle, an immiscible liquid droplet, and/or gas bubble. Equipped with a bimorph force sensor, a computer-interfaced video capture, and a data acquisition system, the newly designed integrated thin film drainage apparatus (ITFDA) allows for the direct and simultaneous measurements of force barrier, true film drainage time, and bubble/droplet deformation under a well-controlled external force, receding and advancing contact angles, capillary force, and adhesion (detachment) force between an air bubble or oil droplet and a solid, a liquid, or an air bubble in an immiscible liquid. Using the diaphragm of a high-frequency speaker as the drive mechanism for the air bubble or oil droplet attached to a capillary tube, this newly designed device is capable of measuring forces over a wide range of hydrodynamic conditions, including bubble approach and retract velocities up to 50 mm/s and displacement range up to 1 mm. The results showed that the ITFDA was capable of measuring hydrodynamic resistance, film drainage time, and other important physical parameters between air bubbles and solid particles in aqueous solutions. As an example of illustrating the versatility, the ITFDA was also applied to other important systems such as interactions between air bubble and oil droplet, two air bubbles, and two oil droplets in an aqueous solution

PENGARUH PUPUK ORGANIK PADAT LIMBAH KELAPA SAWIT DAN PUPUK NITROGEN TERHADAP SIFAT KIMIA TANAH SERTA PERTUMBUHAN DAN HASIL SAWI (Brasicca juncea)

Penggunaan pupuk sintetik dalam jangka panjang dapat merusak tanah dan menurunkan hasil tanaman sehingga tanah tidak mampu lagi meningkatkan produktivitasnya. Hal ini menuntut kita untuk mencari teknologi alternatif yang mampu mengurangi penggunaan pupuk sintetik adalah dengan menggunakan bahan organik. Namun kebutuhan unsur hara yang di butuhkan oleh tanaman tidak semuanya dapat dipenuhi oleh pupuk organik sehingga penggunaannya perlu dikombinasikan dengan pupuk sintetik. Tujuan penelitian ini adalah untuk mendapatkan kombinasi dosis pupuk organik padat dan pupuk nitrogen terhadap sifat-sifat kimia tanah serta pertumbuhan dan hasil sawi. Penelitian ini dilaksanakan pada bulan Juni-September 2016 di rumah kaca dan Laboratorium Ilmu Tanah Universitas Bengkulu. Tanah yang digunakan adalah Ultisol yang berasal dari daerah Kandang Limun Kecamatan Muara Bangkahulu. Pada penelitian ini digunakan benih sawi (panah merah) yang ditanam pada polibag yang disusun berdasarkan Rancangan Acak Lengkap dengan tiga ulangan dan 12 perlakuan yaitu P0N0 Kontrol, P0N1 : 50 kg ha -1 , P0N2 : 100 kg ha -1 urea, P1N0 : 7.5 ton ha -1 POP, P1N1 : 7.5 ton ha -1 POP + 50 kg ha -1 urea, P1N2 : 7.5 ton ha -1 POP + 100 kg ha -1 urea, P2N0 : 15 ton ha -1 tanpa urea, setara dengan 7.5 gr polibag - 1, P2N1 : 15 ton ha -1 POP + 50 kg ha urea, P2N2 : 15 ton ha -1 POP + 100 kg ha -1 urea, P3N0 : 22.5 ton ha -1 tanpa urea, P3N1 : 22.5 ton ha -1 POP + 50 kg ha -1 urea, P3N2: 22.5 ton ha -1 POP + 100 kg ha urea. Variabel pengamatan pada penelitian ini adalah N Total, P tersedia, K-dd, Al-dd, C-Organik, pH H O, Jumlah daun, kehijauan daun, berat basah berangkasan atas, berat basah brangkasan bawah, berat kering berangkasan atas dan berat kering berangkasan bawah. Hasil penelitian menunjukkan bahwa penambahan pupuk organik pada dosis 15 ton ha 2 POP tanpa urea, dapat memperbaiki sifat kimia tanah yang diindikasikan dari peningkatan P tersedia, K dapat ditukar, pH tanah dan penuruan Al-dd pemberian 15 ton ha POP + 100 kg ha -1 urea sampai 22,5 ton ha -1 POP tanpa urea, menghasilkan jumlah daun dan bobot basah tanaman tertinggi. -1 -1 -1 -

Measurement of Interactions between Solid Particles, Liquid Droplets, and/or Gas Bubbles in a Liquid using an Integrated Thin Film Drainage Apparatus

A novel device was designed to measure drainage dynamics of thin liquid films confined between a solid particle, an immiscible liquid droplet, and/or gas bubble. Equipped with a bimorph force sensor, a computer-interfaced video capture, and a data acquisition system, the newly designed integrated thin film drainage apparatus (ITFDA) allows for the direct and simultaneous measurements of force barrier, true film drainage time, and bubble/droplet deformation under a well-controlled external force, receding and advancing contact angles, capillary force, and adhesion (detachment) force between an air bubble or oil droplet and a solid, a liquid, or an air bubble in an immiscible liquid. Using the diaphragm of a high-frequency speaker as the drive mechanism for the air bubble or oil droplet attached to a capillary tube, this newly designed device is capable of measuring forces over a wide range of hydrodynamic conditions, including bubble approach and retract velocities up to 50 mm/s and displacement range up to 1 mm. The results showed that the ITFDA was capable of measuring hydrodynamic resistance, film drainage time, and other important physical parameters between air bubbles and solid particles in aqueous solutions. As an example of illustrating the versatility, the ITFDA was also applied to other important systems such as interactions between air bubble and oil droplet, two air bubbles, and two oil droplets in an aqueous solution

Problematic Stabilizing Films in Petroleum Emulsions: Shear Rheological Response of Viscoelastic Asphaltene Films and the Effect on Drop Coalescence

Adsorption of asphaltenes at the water–oil interface contributes to the stability of petroleum emulsions by forming a networked film that can hinder drop–drop coalescence. The interfacial microstructure can either be liquid-like or solid-like, depending on (i) initial bulk concentration of asphaltenes, (ii) interfacial aging time, and (iii) solvent aromaticity. Two techniquesinterfacial shear rheology and integrated thin film drainage apparatusprovided equivalent interface aging conditions, enabling direct correlation of the interfacial rheology and droplet stability. The shear rheological properties of the asphaltene film were found to be critical to the stability of contacting drops. With a viscous dominant interfacial microstructure, the coalescence time for two drops in intimate contact was rapid, on the order of seconds. However, as the elastic contribution develops and the film microstructure begins to be dominated by elasticity, the two drops in contact do not coalescence. Such step-change transition in coalescence is thought to be related to the high shear yield stress (∼10⁴ Pa), which is a function of the film shear yield point and the film thickness (as measured by quartz crystal microbalance), and the increased elastic stiffness of the film that prevents mobility and rupture of the asphaltene film, which when in a solid-like state provides an energy barrier against drop coalescence