Gradient-Pore Organosilica Ceramic Membrane for Low-Resistance Separation
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Solution Overview
Problem
Traditional composite membranes face issues with large pore size, rough surfaces, and complex manufacturing processes, leading to defects, high mass transfer resistance, and low membrane flux due to the use of porous ceramic supports and traditional coating methods.
Innovation Solution
A method for preparing an organosilica/ceramic composite membrane with a gradient pore structure using zirconium colloidal sols with varying particle sizes, combined with an ultrasonic thermal spraying technique to form a thin, defect-free transition layer, followed by an organosilica polymeric sol coating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional coating methods (dip-coating, scrape coating) are used to prepare separation layer on porous ceramic support, then the separation layer can be formed, but the membrane thickness becomes large and mass transfer resistance increases
Solution Approach 1:
The invention introduces a transition layer with gradient pore structure as a preliminary preparation step before forming the separation layer. This transition layer pre-adjusts the surface morphology and pore distribution, enabling the subsequent separation layer to be formed with optimal thickness and reduced mass transfer resistance, thereby improving membrane flux without sacrificing manufacturing precision
Solution Approach 2:
The transition layer employs gradient pore structure where pore size and distribution vary locally from the support interface toward the separation layer. This local variation in pore quality allows different regions to serve different functions: larger pores near the support for mechanical strength and smaller pores near the separation layer for selective transport, thus reducing overall mass transfer resistance while maintaining precise thickness control
2Reliability
If traditional coating methods are used on porous ceramic support, then separation layer can be deposited, but defects are easily caused due to large pore size and rough surface
Solution Approach 1:
The transition layer is formed in advance to modify the ceramic support surface before applying the separation layer. This preliminary action reduces surface roughness and fills large pores, creating a smoother substrate that prevents defects during separation layer deposition, thereby improving membrane quality without significantly increasing process complexity
Solution Approach 2:
The transition layer acts as an intermediary between the rough porous ceramic support and the separation layer. It mediates the interface by providing a graded transition in pore size and surface morphology, preventing direct contact between the separation layer and the problematic rough surface, thus eliminating defects while maintaining process simplicity
3Manufacturing precision
If multiple coating layers are applied to form transition layer with thickness >1 μm, then the support surface roughness is reduced, but mass transfer resistance increases and membrane flux decreases
Solution Approach 1:
Instead of uniformly thickening the transition layer, the invention creates a gradient pore structure where pore size and density vary locally through the layer thickness. This local quality variation allows the transition layer to achieve surface smoothing and pore size reduction functions with minimal overall thickness, preventing excessive mass transfer resistance and maintaining high membrane flux
Solution Approach 2:
The invention changes the pore size parameter gradually from the support interface toward the separation layer, creating a continuous gradient rather than a uniform structure. This parameter change allows the transition layer to achieve effective surface smoothing and pore refinement in a thin configuration, avoiding the mass transfer resistance problems associated with thick uniform layers while maintaining flux performance
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method results in a membrane with reduced mass transfer resistance and improved flux, achieving a thin, uniform, and defect-free separation layer with enhanced porosity and performance in dye and salt separation systems.
Implementation Method 1
adding water and hydrochloric acid, heating the above solution to be boiled and maintaining the boiling state, and gradually adding water during the boiling to replace isopropanol
Implementation Method 2
catalyzing hydrolytic polymerization reaction of an organosilica precursor and an isopropanol solution with water by adding hydrochloric acid
Implementation Method 3
evenly spraying the organosilica polymeric sol on the prepared membrane transition layer through an ultrasonic thermal spraying technology
Implementation Method 4
ultrasonic thermal spraying technology to undergo heat treatment
Implementation Method 5
form a membrane transition layer with a gradient pore structure
Data Source
AI summary
The present disclosure discloses a preparation method of an organosilica/ceramic composite membrane with a gradient pore structure. The preparation method comprises: (1) selecting a porous ceramic material as a membrane support layer; (2) gradually replacing a solvent with water to prepare zirconium colloidal sols with different particle sizes, and successively coating the prepared zirconium colloidal sols onto a ceramic support from large to small so as to form a membrane transition layer with a gradient pore structure; and (3) catalytically synthesizing an organosilica polymeric sol using hydrochloric acid, coating the prepared organosilica sol onto the preheated transition layer through ultrasonic thermal spraying to undergo heat treatment, so as to prepare the organosilica/ceramic composite membrane with the gradient pore structure. According to the present disclosure, the transition layer with the gradient pore structure is prepared by using the zirconium colloidal sols with different particle sizes. An ultrathin defect-free organosilica separation layer is prepared through ultrasonic thermal spraying. As a result, the obtained organosilica/ceramic composite membrane can be applied to the fields of salt-containing dye wastewater treatment and polypeptide bioactive substance separation.