Acid separation and purification technologies are of great significance in areas such as acid purification and waste acid recovery and reuse. They not only improve the recycling rate of acids but also reduce waste acid treatment costs. Currently, for mixed systems of sulfuric acid and phosphoric acid, there is no readily available direct separation technology in China. Methods such as evaporation or adding chemical agents can only recover one type of acid, failing to obtain both sulfuric acid and phosphoric acid at relatively high purity, and the treatment costs are high. To address this industry challenge, Guochu Technology has developed a specialty acid separation membrane technology that can be used for separating sulfuric acid and phosphoric acid. After membrane separation, the mixed solution of sulfuric acid and phosphoric acid yields sulfuric acid and phosphoric acid respectively.
A membrane is a material with selective separation functionality. The process of using the selective separation function of a membrane to separate, purify, or concentrate different components of a feed solution is called membrane separation. Membrane separation can be performed on a molecular scale, and since it is a physical process, it does not involve phase changes or the addition of auxiliary agents, nor does it introduce other impurities. Because membrane separation is a purely physical process, it offers advantages such as no phase change, energy savings, a small footprint, and modular disassembly, making membranes widely used in fermentation, pharmaceuticals, chemicals, water treatment processes, and environmental protection industries.
To achieve the separation and purification of different acids, it is necessary to select specialty acid-resistant membranes; ordinary water treatment membranes cannot withstand acidic systems. Conventional acid-resistant membranes are unable to effectively separate sulfuric acid and phosphoric acid. The key to separating sulfuric acid and phosphoric acid lies in the permselectivity of the membrane. Leveraging its profound expertise in novel separation technologies accumulated over many years, Guochu Technology (Xiamen) Co., Ltd. has successfully developed a new specialty acid separation membrane process. This acid separation membrane possesses unique permselectivity: when a mixed solution of sulfuric acid and phosphoric acid passes across the membrane surface, sulfuric acid permeates through the membrane to the other side, while phosphoric acid is retained in the original acid solution, thus achieving the separation of sulfuric acid and phosphoric acid. The process is illustrated in the figure below:
It is worth mentioning that Guochu Technology's specialty acid separation membrane technology is applicable not only to the separation of sulfuric acid and phosphoric acid but also to the separation and purification of other mixed acid systems such as phosphoric acid/hydrochloric acid and phosphoric acid/nitric acid. The successful development of this technology not only solves a major industry problem but also provides new ideas for the green development of the chemical industry.
In addition to mixed acid separation membranes, Guochu Technology has also developed specialty separation membranes for acid applications, including acid salt separation membranes and acid concentration membranes.
Process advantages:
High selectivity: The membrane material exhibits differential rejection of sulfate ions (SO₄²⁻) and phosphate ions (PO₄³⁻), achieving high separation efficiency.
Strong acid corrosion resistance: The membrane modules can operate stably for long periods in high acid concentration environments, offering a long service life.
Low energy consumption: Ambient temperature operation without phase change results in lower energy consumption compared to conventional processes.
Zero pollution discharge: No chemical additives are used throughout the process, and waste acids can be recycled, significantly improving environmental compliance.
Application areas:
Lithium battery material production:
In the preparation of lithium iron phosphate (LiFePO₄) cathode materials, separate and recover sulfuric acid and phosphoric acid to realize waste acid resource utilization and reduce raw material costs.
Hydrometallurgy industry:
Efficiently extract phosphoric acid from sulfuric acid containing phosphate rock leach solutions, avoiding interference from impurities and improving metal recovery rates.
Chemical intermediate purification:
For mixed acid systems (e.g., sulfuric acid/phosphoric acid mixtures), use membrane separation to obtain sulfuric acid and phosphoric acid products of relatively high purity.
Guochu Technology (Xiamen) Co., Ltd. is a high tech enterprise focused on novel separation technologies, dedicated to the promotion and application of membrane separation and purification technologies. The company provides integrated filtration and purification solutions for industries such as biopharmaceuticals, food and beverages, deep processing of agricultural products, petrochemicals, environmental water treatment, and chemicals. By leveraging membrane separation technology to assist customers in upstream and downstream process integration and innovation, Guochu Technology helps enterprises save investment, reduce operating costs, lower unit consumption, improve product quality, maintain clean production environments, and facilitate industrial upgrading.
