Microfiltration has been widely used in biochemical pharmaceutics, biological fermentation, amino acid purification, industrial water treatment, etc. At present, microfiltration is used to filter into protein molecules, but due to the strong hydrophobicity of the filtration membrane, the double charge effect of protein substances makes In the process of purifying and separating such materials, the separation mechanism of the membrane is not only the sieving effect of the membrane pores, but the adsorption and repulsion between the membrane surface and the protein and between the protein molecules cannot be ignored. Dai Haiping [1] studied the effect of operating conditions and solution properties on the membrane retention performance during the process of polyfluorinated vinyl fluoride (PVDF) microfiltration membranes for the retention of gamma globulin. The results showed that the transmembrane pressure difference was from 0.02 MPa. When the temperature rises to 0.12 MPa, the membrane retention rate of protein increases from 31.5% to 94.4%; the extended run time and the increase of the concentration multiple increase the rejection rate; the membrane rejection and flux reach the highest in the protein solution at pH 7.0, respectively. And the lowest value, when the salt content in the solution increases, the flux increases slightly. When the salt mass concentration exceeds 20000 mg/L, the flux decreases and the rejection rate increases.
The XFM microfiltration system and ROM micro high pressure reverse osmosis system (see Figure 1), represented by Shanghai Ruiyi International Trading Co., Ltd., are from the highly developed US, where the XFM microfiltration system is suitable for microfiltration, working pressure is 150 psi, filtration The contact area of ​​the spiral wound structure of the film reached 334 m 2 . The applicable range of micron-sized membranes is shown in Figure 2. It is an ideal system for protein filtration;
The pressure reverse osmosis system is more precise than XFM. It has a working pressure of 1000 psi and can work continuously for 24 hours. ROM is not only suitable for microfiltration membrane (MF), but also for reverse osmosis membrane (RO) and nanofiltration membrane (NF). Ultrafiltration membrane (UF), which in turn enhances its range of applications, so it is easy to use a microfiltration membrane to filter proteins.
In short, protein research is a hot issue in current research institutions. The birth of microfiltration technology has provided great convenience for protein separation research. XFM microfiltration system and ROM micro high pressure reverse osmosis system represented by Shanghai Ruiyi International Trade Co., Ltd. It can quickly and efficiently separate protein molecules and is an indispensable instrument for scientific research institutions and experimental teaching.
References :
[1]Dai Haiping, Zhang Huixin, Sun Fang, et al. Effects of operating conditions and solution properties on the retention of propionin by PVDF hollow fiber microfiltration membrane[J]. Journal of Donghua University(Natural Science), 2005, 31(3) ): 119-122.
Sprinkler irrigation and micro-irrigation automatic control equipment With the development of economy, water resources, energy shortage and labor cost increase, more and more water-saving irrigation systems will adopt automatic control. This article focuses on the advantages and classification of automated irrigation.
The advantages are as follows:
(1) It is possible to truly control the amount of irrigation, irrigation time and irrigation cycle in a timely and appropriate manner, thereby increasing crop yield and significantly improving water utilization.
(2) Saving labor and operating expenses.
(3) The work plan can be arranged conveniently and flexibly, and the management personnel do not have to go to the field at night or other inconvenient time.
(4) Since it can increase the effective working time every day, the initial capital investment in pipelines, pumping stations, etc. can be reduced accordingly.
classification:
First, fully automated irrigation system
The fully automated irrigation system does not require direct human involvement. The pre-programmed control procedures and certain parameters that reflect the water requirements of the crop can automatically open and close the pump for a long time and automatically irrigate in a certain order. The role of the person is simply to adjust the control program and overhaul the control equipment. In this system, in addition to emitters (heads, drip heads, etc.), pipes, fittings, pumps, and motors, it also includes central controllers, automatic valves, sensors (soil moisture sensors, temperature sensors, pressure sensors, water level sensors, and rain sensors). Etc.) and wires.
Second, semi-automatic irrigation system
In the semi-automated irrigation system, no sensors are installed in the field. The irrigation time, irrigation volume and irrigation period are controlled according to pre-programmed procedures, rather than feedback based on crop and soil moisture and meteorological conditions. The degree of automation of such systems is very different. For example, some pump stations implement automatic control, and some pump stations use manual control. Some central controllers are only one timer with simple programming function, and some systems have no central control. The controller, but only some of the sequential switching valves or volume valves are installed on each branch pipe.
Automated irrigation is the trend of the times. In the future water-saving irrigation projects, more and more automated irrigation systems will be applied.
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