Papers by Keyword: Ultra-Filtration

Abstract: Numerous computational simulations have been performed for the study of the ultra-filtration using carbon nanotubes. However, most carbon nanotubes have dangling bonds at nanotube rims, which severely compromise the validity of such computational simulations. In this paper, we use applied mathematical modeling and the continuous approximation to investigate the acceptance conditions for the water and ions permeating through the functionalized carbon nanotube, and in particular the sodium and chloride ions. Such problem is important for future ion transport and detection. For the nanotube of radius 3.8 Å, while the presence of a tiny positive charge at the nanotube rim will prevent water from entering the nanotube, the presence of a negative charge at the nanotube rim will always enhance the water absorption. With a proper tuning of the total charge at the nanotube entry, we can selectively sieve the sodium or chloride ions. The mathematical framework presented here possesses the merit of delivering deductive and rapid results.

Abstract: Packaging process is one of the main manufacturing steps in the wafer fabrication industries. However, nano-particles would be produced during the packaging process. The produced nano-particle-contained wastewater has characteristics of dark color and high turbidity. Because the nano-particles would usually result in the clogging of the membrane filtration system when it is used for water treatment and reclamation, the application of a pre-treatment system is required to extend the membrane life. The objective of this study was to develop a pre-treatment system for packaging wastewater treatment before membrane system was applied for further water quality improvement. In this laboratory-scale study, a hybrid treatment system containing a chemical coagulation/flocculation followed by ultra-filtration (UF) membrane technology was developed for the wafer fabrication wastewater treatment. The chemical coagulation/flocculation unit was used as the pre-treatment process to improve the efficiency of the following ultra-filtration (UF) membrane system. The packaging wastewater was collected from a wafer fabrication factory and used to evaluate the feasibility of the coagulation/flocculation process on nano-scale particle removal. Results show that approximately 98% of turbidity could be removed at pH 7 when 2.2 mg/L of polyaluminum chloride (PAC) (used as coagulant) and 0.5 mg/L of polyacrylamide (cPAM) (used as flocculant) were added during the coagulation/flocculation process. Results indicate that the coagulation/flocculation is a feasible pre-treatment process for nano-particle removal before UF membrane is applied for further water purification. Results from this study will be helpful in designing a scale-up system for practical applications.

Abstract: Spinning effluents (SE) from dry-spun acrylic fiber producing are hard to biodegrade for dimethyl formamide (DMF) and nitriles contained. Integrated membrane filtrations including micro-filtration (MF), ultra-filtration (UF) and nano-filtration (NF) were adopted to separate the pollutants in SE. Experiment showed that MF has weak capacity for the removal of organic pollutants, while NF and UF contributed to 49.49% and 31.51% to the initial COD removal rates of SE.