Nanofiltration Purification of Wet Phosphoric Acid
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Solution Overview
Problem
Current methods for purifying wet phosphoric acid are inadequate in effectively reducing sulfate and metallic impurities to desired levels, particularly in achieving the stringent purity requirements for food-grade phosphoric acid.
Innovation Solution
A method involving multiple nanofiltration stages, where the wet phosphoric acid feed is processed through a first nanofiltration stage to produce a permeate with reduced sulfate and metallic impurities, followed by additional nanofiltration stages and treatment with a barium salt to precipitate sulfate solids, achieving significant reductions in impurity concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional purification methods (evaporation, solvent extraction) are used, then phosphoric acid can be concentrated, but sulfate and metallic impurities cannot be reduced to desired levels
Solution Approach 1:
The patent employs nanofiltration membranes with specific pore sizes and charge characteristics to selectively remove sulfate and metallic impurities from phosphoric acid. The membranes act as porous barriers that allow phosphoric acid molecules to pass while retaining larger sulfate ions and metallic impurities, achieving both concentration and high-purity removal that conventional methods cannot accomplish
Solution Approach 2:
The patent replaces conventional mechanical/thermal purification methods (evaporation, solvent extraction) with a membrane-based separation process. This substitution enables precise molecular-level separation based on size and charge differences, achieving superior impurity removal efficiency without the limitations of traditional mechanical systems
2Manufacturing precision
If multiple conventional purification steps are added to reduce impurities, then purity increases, but process complexity and energy consumption increase
Solution Approach 1:
The patent segments the purification process into distinct functional zones within the nanofiltration membrane structure, with different membrane layers or regions targeting different impurity types. This segmentation allows a single integrated unit to perform multiple purification functions that would otherwise require separate process stages, reducing overall system complexity while maintaining high purity levels
3Ease of manufacture
If conventional purification methods are used, then processing is simpler, but energy consumption is high due to evaporation requirements
Solution Approach 1:
The patent replaces energy-intensive thermal evaporation processes with a membrane filtration system that operates at ambient or near-ambient temperatures. The nanofiltration membranes utilize size exclusion and electrostatic repulsion mechanisms to separate impurities without requiring phase change or high energy input, dramatically reducing energy consumption while maintaining process simplicity
Solution Approach 2:
The patent changes the operating parameters from high-temperature evaporation conditions to low-temperature membrane filtration conditions. By operating at lower temperatures and utilizing pressure-driven flow through the membranes, the process achieves the same purification goals with minimal energy input, transforming an energy-intensive thermal process into an efficient mechanical separation process
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
This process results in a purified phosphoric acid with concentrations of sulfate and metallic impurities below the specifications for food-grade phosphoric acid, reducing the need for additional purification steps and improving energy efficiency by concentrating the acid to higher levels while minimizing impurity content.
Implementation Method 1
subjecting the wet phosphoric acid feed to a first nanofilter in a first nanofiltration stage
Implementation Method 2
passing the phosphoric acid stream through an additional nanofilter in at least one additional nanofiltration stage
Implementation Method 3
treating the first permeate to produce sulfate solids
Data Source
AI summary
A method of purifying phosphoric acid solution produced in wet process using nanofiltration. The claimed method contains the following: (a) providing wet phosphoric feed (b) subjecting the said feed to a first nanofilter (c) produce sulfate solids (d) removing the solids (e) subjecting a second nanofilter.