کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
608488 880597 2011 8 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Cluster–cluster aggregation simulation in a concentrated suspension
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی شیمی کلوئیدی و سطحی
پیش نمایش صفحه اول مقاله
Cluster–cluster aggregation simulation in a concentrated suspension
چکیده انگلیسی

The collision radius of a floc is an indispensable parameter for the precise description of the rate of aggregation during the development of particle flocs with a wide size distribution. Herein, we report on the characteristics of the collision radius of fractal aggregates formed by off-lattice diffusion-limited cluster–cluster aggregation (DLCCA) simulations, and discuss aggregation kinetics based on the value of the estimated collision radius. The collision radius has a fractal relationship with the number of primary particles that compose the floc. Further, the obtained fractal dimensions of flocs increase from the normally accepted value of 1.6–1.8 to a value of ∼2.5 when the initial volume fraction is above 8%. From an assessment of the partial radial distribution function of the particles, the increase of the fractal dimensions determined by the collision radius can be attributed to a change in the spatial distribution of neighboring particles. The DLCCA simulation also reveals an apparent increase in the rate of aggregation upon an increase in the initial volume fraction. For a relatively low initial volume fraction, the enhancement of the aggregation rate is expressed by a population balance equation taking into account additional factors, i.e., transient collision flux among particles/flocs, excluded volumes, and polydispersed features of flocs. However, for cases with high initial volume fractions, the population balance model that accounts for these three factors overestimates the aggregation rate, which supports the concept of a caging effect.

Above ∼8% initial volume fraction, fractal dimension of collision radius of flocs increases up to 2.5. Also, the DLCCA simulation demonstrates qualitative shift of the particle distribution function around this critical volume fraction.Figure optionsDownload high-quality image (67 K)Download as PowerPoint slideHighlights
► We characterize collision radius of flocs by DLCCA simulation.
► Fractal dimension of collision radius abnormally increases with volume fraction.
► We relate the increase of fractal dimension to partial radial distribution function.
► The caging effect exhibited here also affect rate of aggregation.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Colloid and Interface Science - Volume 363, Issue 1, 1 November 2011, Pages 34–41
نویسندگان
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