Stability and flocculation of nanosilica by conventional organic polymer

Abstract

More than 2,000,000 tons of silica nanoparticles (NPs) are produced annually in the world to cover the needs of nanotechnologies. Inevitably, a quantity of NPs, will be in industrial discharges and domestic, or even in water resources. Share their high surface reactivity, these NPs may also carry with them through a specific adsorption of other toxic chemical pollutants inherent to the industrial sectors. To preserve public health and the environment from this pollution, it is necessary to remedy the potential pollution. In this context, the main motivation of this work is to answer this environmental issue by proposing a scheme of remediation based on the use of a conventional treatment process. The process of elimination nanoparticles by coagulation/flocculation was selected for its simplicity and also for its universal use. The NPs of industrial silica S30R50 were used as support to develop the process. The optimization of coagulation/flocculation, was greatly facilitated by the use of laser diffraction online. This technique allowed to follow the dynamic character of the treatment and to determine the size and the most relevant textural parameters (density, porosity and fractal dimension) of the flocs depending on the nature of the used reagents. The critical concentrations of different coagulants and flocculants used were determined by electrophoresis and turbidity. The ratio of their charge density/molecular weight has conditioned the quality of separation, the floc size and their texture. Excellent coagulation/flocculation performances are reached using organic reagents authorized by the Directorate General for Health of several countries. After optimization of the process, the size distributions are between 10 µm and 1 mm, with fractal dimensions (compactness) ranging from 2.3 to 2.5. The performances obtained show that the use of cationic polymers is a promising potential route to treat other types of NPs. The treatment proposed to reach a ratio of average diameters d<sub>Floc</sub>/d<sub>NP</sub> of 3500, and therefore it facilitates the elimination of these NPs agglomerated by filtration

Effect of Anionic Polyacrylamide on the Structural Stability of Thickened Tailings Slurry in Pipeline Transportation

“…e Zetasizer Nano uses electrophoresis to determine this potential. e electrophoretic mobility is related to the zeta potential of the particles by the Henry equation, Ohshima's approximation, and Smoluchwski's formula [17,18]:…”

Silica nanoparticles separation from water: Aggregation by cetyltrimethylammonium bromide (CTAB)

“…and suitable additives (if necessary) for water containing nanoparticles. Recently, Bizi (2012) has investigated the coagulation and flocculation of nanosilica by some organic polymers. The treatment of CMP effluents by chemical coagulation with polyaluminium chloride has been studied by Chang et al (2007).…”

Interaction of Freshwater Diatom with Gold Nanoparticles: Adsorption, Assimilation, and Stabilization by Cell Exometabolites

“…The adsorption of AuNPs on EOMI diatoms was studied as a function of time (0-3 h and 1-55 days), pH (3)(4)(5)(6)(7)(8)(9)(10), and AuNPs concentration in solution (1-1000 µg/L). Although this range of concentration exceeded that of real cases found in contaminated environments linked to industrial and hospital waste, the concentration of diatoms used in our experiments was also several orders of magnitude higher than that encountered in freshwater aquatic environments, so that the ligand to metal ratio in the experiments was similar to that in natural settings.…”

“…Together with other nanoparticles in aquatic systems, AuNPs are also investigated for their use as decontamination devices. For example, coagulation or flocculation techniques of nanoparticles by organic molecules have been developed [6][7][8], and the efficiency of gold nanoparticles as low-molecular-weight-chelators in aqueous suspensions has been demonstrated [9]. However, their harmless nature has yet to be proven for living organisms in the natural environment.…”