Technical assistance: Regarding the molecular weight of membrane cutting
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This post was last edited by hesonchang214 on 2010-4-21 at 16:41. Dear seniors: In the information related to membranes, the term \"cutting molecular weight\" is often mentioned. Does it refer to the size of impurity particles that the membrane can retain? If that’s the case, then what size of impurity particles can be retained by a cutting molecular weight of 100,000? Looking forward to your advice!
This post was last edited by cdpulin on 2010-4-22 at 11:05. There is no exact conversion relationship between molecular weight cut-off and retention particle size, as different membrane manufacturers use various standards to define the performance of their membranes. There is a rough comparison in the “membrane separation spectrum,” but it is only for reference; moreover, the performance of membranes made from different materials also varies. All organic ultrafiltration membranes, or some ceramic ultrafiltration membranes, have their performance characterized by the molecular weight cutoff; whereas some manufacturers use pore size to specify the properties of their ceramic ultrafiltration membranes. Based on personal experience, the performance of organic ultrafiltration membranes with a molecular weight of 100,000 is equivalent to that of ceramic membranes with a pore size of 50 nm. Ceramic ultrafiltration membranes with a molecular weight of 100,000 are similar to ceramic membranes with a pore size of 20 nm. This is determined by the material of the membrane itself. I’m not sure if what I’m saying is a bit off-topic; if you have any doubts, we can discuss it further
The membrane’s cut-off molecular weight (MWCO) is commonly used to describe the pore size of ultrafiltration membranes; it roughly refers to the lowest molecular weight of substance that can be retained by the membrane in over 90% of cases. For the MWCO of conventional ultrafiltration membranes, there are many values provided by different manufacturers, ranging from a few thousand to several hundred thousand.
The cut molecular weight is related to the membrane pore size, the membrane material, as well as the molecular structure of the macromolecules used for calibration; nanofiltration typically involves molecular weights in the range of a few hundred, while ultrafiltration can cover ranges from a few thousand to several hundred thousand. Since the molecules that need to be separated during production are generally different from those used for calibration, it is recommended to conduct experiments for verification.
The performance of organic ultrafiltration membranes with a molecular weight of 100,000 is equivalent to that of ceramic membranes with a pore size of 50 nm; ceramic ultrafiltration membranes with a molecular weight of 100,000 are similar to ceramic membranes with a pore size of 20 nm
Upstairs, I wonder if you agree with my view. .
This post was last edited by baby_tree on 2010-4-26 at 11:58. Such information is rarely found in materials and literature; everything mentioned here is based on personal experience. If you have any doubts, please feel free to discuss them actively
Reply to 2# baby_tree: Okay, this is the first time I’ve heard of cutting molecular weight; it’s interesting
I would like to know that too as well, thank you
It is related to the shape of the molecules being retained – linear or spherical – and the retention pore size follows a distributed curve, representing a range of values. It is recommended to conduct experiments using membranes with different pore sizes!
Baby-tree, do you have a map with membranes? Could you share it? Thank you!