Abstract
The instability of diafiltration is a widespread problem in the practical application of microporous ceramic filtration membranes. In this paper, a series of microporous ceramic filter membranes were prepared using inexpensive standard sand and river sand as matrix materials. Semi-empirical formula for the effective permeability radius of ceramic membranes with respect to time was established from analysis of the response mechanism between water flow and material properties. Finally, on the basis of theoretical analysis, some measures were proposed to improve permeate flux. The experimental results showed that during the initial stage of filtration, the microporous ceramic filter membrane had a large change in permeate flux, and during the late stage of filtration, permeate flux tended to be stable. Over time, open porosity and closed porosity changed the actual seepage area of the ceramic membrane, and this affected the stability of permeate flux and final stable permeate flux. The roughness of the inner wall of microporous ceramic pores affected the hydraulic loss coefficient, and this controlled the outflow process. Trace elements that were rich in sand produced a large amount of glass phase after sintering. The glass phase was rich in polar groups and formed a temporary hydrogen bond with the small flow of water molecules. It led to an increase in viscous resistance effect of the side wall along the water flow and the extent of the permeate flux of the ceramic membrane changed with time.
Highlights
Membrane filtration is an effective method for removing particulates, microorganisms, and organic matter from wastewater [1]
Microporous ceramics have been widely used in the preparation of microfiltration or ultrafiltration materials because of they have the advantages of heat resistance, chemical resistance, mechanical resistance, controllable microstructure, and low environmental pollution [8,9,10]
We proposed some reasonable approaches to improve the permeability of ceramic membranes
Summary
Membrane filtration is an effective method for removing particulates, microorganisms, and organic matter from wastewater [1]. Membrane treatment (i) provides higher water quality, (ii) minimizes disinfectant requirements, (iii) is more compact, (iv) provides easier operational control and less maintenance than conventional treatments, and (v) produces less sludge [2,3,4,5,6]. Conventional microfiltration membranes are mostly prepared using polymers, but they are costly and have poor durability [7]. Microporous ceramics have been widely used in the preparation of microfiltration or ultrafiltration materials because of they have the advantages of heat resistance, chemical resistance, mechanical resistance, controllable microstructure, and low environmental pollution [8,9,10]. Sui used a centrifugal casting method to prepare a gradient diatomaceous earth film that can remove 100% of pathogenic bacteria, rust bacteria, worms, and suspended particles in Materials 2019, 12, 2161; doi:10.3390/ma12132161 www.mdpi.com/journal/materials
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