The reason why the conventional acid recovery membrane can achieve the separation of acid and impurities lies in its unique membrane material properties. Taking the ion-exchange membrane as an example, such as the perfluorosulfonic acid membrane, its molecular structure contains special functional groups. These functional groups have a specific affinity for acid anions. In complex waste liquid systems, acid exists in the solution in the form of ions, for example, sulfuric acid exists in the form of hydrogen ions and sulfate ions. The functional groups in the membrane material can interact with the acid anions, creating conditions for the selective permeation of acid. However, for impurities, such as metal ions and insoluble particles, they do not have this specific interaction with the membrane material.
From the perspective of the membrane pore size, the pore design of conventional acid recovery membranes is an important factor for achieving separation. The pore size of the membrane is usually carefully controlled, allowing anions and accompanying hydrogen ions to pass through. For larger impurities, such as colloidal particles formed by metal ions or insoluble solid impurities, their sizes are far beyond the membrane pore size, and thus are effectively blocked on one side of the membrane. For example, iron particles or iron oxide precipitates that may exist in the steel acid washing wastewater cannot pass through the acid recovery membrane, thereby achieving separation from the acid.
The selectivity of the membrane is also a key factor in separation. The conventional acid recovery membranes have selectivity towards acids, and this selectivity is based on the chemical interaction between the membrane material and the acid molecules or ions. In complex systems, different acids may have different chemical properties, but the acid recovery membranes can identify and allow the passage of acids based on their own chemical structure. For example, in a mixed acid waste liquid containing both hydrochloric acid and nitric acid, the membrane can selectively promote the diffusion and recovery of hydrochloric acid and nitric acid based on the different characteristics of the acid anion, while for the possible organic impurities, heavy metal ions, etc. present in the waste liquid, since there is no such selectivity interaction, they are left on the waste liquid side.
In the actual separation process, the concentration difference-driven mechanism also plays a crucial role. A concentration difference is formed on both sides of the membrane, which is an essential condition for the operation of the acid recovery membrane. The acid concentration on the waste liquid side is higher, while the acid concentration in the receiving liquid on the other side is lower. According to the principle of diffusion, the acid anion ions will diffuse from the high concentration area to the low concentration area. This diffusion process driven by the concentration difference is spontaneous, and under the selective action of the membrane, only the acid can migrate along this concentration gradient. And impurities, due to their inability to participate in this special diffusion process determined by the membrane, are left in the waste liquid.
In addition, the operating conditions also affect the separation effect of the acid recovery membrane on acid and impurities. Factors such as temperature and flow rate need to be properly controlled. Slightly increasing the temperature can accelerate the movement speed of acid molecules and ions, thereby improving the membrane's flux and separation efficiency to a certain extent. However, excessively high temperatures may affect the stability of the membrane. An appropriate flow rate ensures that the waste liquid can fully contact the membrane surface, allowing the acid to diffuse through the membrane in time and preventing impurities from excessively accumulating on the membrane surface and affecting its performance.
Shanghai Sanji New Materials Technology Co., Ltd. is led by foreign researchers specializing in membrane materials, jointly established by the research team from East China University of Science and Technology and the professional management team. The company focuses on the independent research, production and application of high-performance polymer membrane products for fluid separation. Its main products are functional new materials independently developed. It provides high-performance and cost-effective polymer materials and equipment with excellent performance to domestic industrial customers and integrators in fields such as clean production, environmental governance & monitoring, waste resource utilization, medical health, and new energy. The conventional acid recovery membrane is one of the main products of Shanghai Sanji New Materials Technology Co., Ltd. With years of supply and production experience, it enjoys a good reputation in the industry. The product quality is excellent, the inventory is sufficient. If you want to know more, please feel free to call for communication.
