Ionic Strength Acrylic Acid: Preparedness & Absorption Features

Singhae Tamudeen^*
*Correspondence: Singhae Tamudeen, Department of Chemical and Biochemical Engineering, Western University, London, UK, Email:

Introduction

Applications for a pH-responsive membrane include drug delivery, regulating chemical release, bioprocessing, and water treatment. A polymer that responds to pH, polyacrylic acid (PAA) swells at high pH levels. By grafting to introduce the proper functional groups, then polymerizing with acrylic acid, a tubular -alumina porous support was coated with PAA. By circulating water inside the membrane, measuring the concentration of species that permeated into the water, and then analyzing the results using the permeation model, the presences of acetic acid, lactic acid, phenol, and caffeine were assessed. All species' presence decreased as pH rose, but phenol had the greatest permeance among these species. The membrane's PAA carboxy group split apart into carboxy ions and at high pH, Due to electrical repulsion between the negative charges in the PAA chain caused by protons, the PAA chain swelled, reducing the membrane's pore size and inhibiting permeation. Additionally, the permeation was suppressed by the electrical attraction between negatively charged species and the PAA membrane. According to the study's findings, the porous -alumina support coated with PAA served as a pH-responsive membrane [1].

Description

Biological and chemical separation, drug delivery, chemical release control, water purification, and pH-responsive permeation systems have all received attention in recent years. They are also a key technology for creating high-performance separation systems. These pH-responsive membranes are typically made from pH-responsive polymers and are anticipated to be a major method of enabling simple separation based on the pH of the environment. For instance, membranes have been made from pH-responsive polymers such as poly (meth acrylic acid-co-ethylene glycol methacrylate), polyacrylic acid (PAA), or polymers containing PAA; calcium ion cross-linked sodium alginate on polyvinylidene fluoride, dimethyl amino ethyl methacrylate-4-vinylpyridine, polypyrrole-polysulfone, poly (N-isopropyl)

Since PAA has a straightforward structure and swells at high pH levels, it is a widely used polymer. A PAA-coated porous alumina support, PAAcoated porous polymers, a PAA-coated Nano sheet, and a PAA-grafted carbon nanotube-intercalated membrane are examples of structures that use PAA as a gate membrane. As pH-responsive membranes, mixed polymers made of PAA and other polymers are also employed. On occasion, phase separation results in the formation of a sponge-like structure. Examples include PAApolyvinylidene fluoride, PAA-polyvinylidene fluoride, PAA-polyvinyl pyrimidine, PAA-polystyrene, PAA-poly-N-isopropyl acrylamide, and PAA-polyvinyl alcohol. A membrane with ZnO particles covered in PAA exhibited pH responsiveness [2].

Gate membranes with a stable inorganic support, like -alumina, have demonstrated exceptional chemical stability and durability. However, the inorganic support for reported PAA gate membranes is a thin, fragile alumina disc, and specific coating methods, like plasma coating, have been used. Industrial uses call for a support with high mechanical strength and a straightforward coating method. Additionally, the permeation of a solvent, caffeine, sugar, a pigment, phosphate, copper, dextran, bovine serum albumin, vitamin B12, tryptophan, and urea have been used to assess the pH responsiveness of the PAA membrane. As far as the authors are aware, there have been no studies that compare the permeance of different species for a given membrane.

A circulation system was used to assess the species permeations of acetic acid, lactic acid, phenol, and caffeine in both single and combined aqueous solutions. The PAA-coated alumina membrane was immersed in test solution in a beaker after being covered with Teflon tape at both ends, leaving a 50 mm exposed length. Water from a second beaker was added while being stirred, and a pump was used to move the water through the first beaker's membrane tube. At each predetermined time, a few milliliters of the sample were taken and analyzed using an HPLC-UV system equipped with an Inertsil ODS-4 column [3].

The permeation mechanism through the PAA-coated alumina membrane is discussed in this section, and we also suggest a mechanism for the permeation pH dependence. The PAA carboxy groups in the membrane did not dissociate at low pH, and the membrane's large pore diameter made it simple for all species to pass through. The PAA carboxy group split apart as the pH rose, forming protons and carboxy ions [4]. The PAA polymer chains grew due to the electrostatic attraction of negatively charged carboxy ions, which reduced the membrane pore size as pH rose. Because of the PAA carboxy ions, the membrane surface became negatively charged with rising pH; consequently, negatively charged species in solution were repelled from the membrane surface [5].

Conclusion

The characteristics of the species used for the permeation test are then outlined. the species used for the permeation test and their pKa and molecular weight. Caffeine had the highest pKa, followed by phenol, acetic acid, lactic acid, and then phenol. At low pKa, protons readily dissociate to form negative ions. The order of molecules' molecular weights, which is a gauge of their size, is caffeine > phenol > lactic acid > acetic acid. The electrical density of a molecule increases with decreasing molecular size for molecules with the same negative charge. The order of acetic acid, lactic acid, phenol, and caffeine for the magnitude of the negative electrical density of the ions.

The electrical repulsion at high pH was the main factor in suppressing the permeation of acetic acid and lactic acid. Compared to other species, caffeine's permeation was more affected by molecular size. Because phenol's electrical repulsion was relatively low and it was smaller than caffeine, there was likely less permeation suppression, resulting in phenol having a much higher permeation than other species.

Acknowledgement

None.

Conflict of Interest

There is no conflict of interest by author.

References

1. Kiatkamjornwong, Suda, Wararuk Chomsaksakul and Manit Sonsuk. "Radiation modification of water absorption of cassava starch by acrylic acid/acrylamide." Radiat Phys Chem 59 (2000): 413-427.

Google Scholar, Crossref, Indexed at

2. Wu, Yan, Jia Guo, Wuli Yang and Changchun Wang, et al. "Preparation and characterization of chitosan–poly (acrylic acid) polymer magnetic microspheres." Polymer 47 (2006): 5287-5294.

Google Scholar, Crossref, Indexed at

3. Mittal, H., Shivani B. Mishra, A. K. Mishra and B. S. Kaith, et al. "Preparation of poly (acrylamide-co-acrylic acid)-grafted gum and its flocculation and biodegradation studies."     Carbohydr Polym 98 (2013): 397-404.

Google Scholar, Crossref, Indexed at

4. Paloma, M., Susana Torrado and Santiago Torrado. "Interpolymer complexes of poly (acrylic acid) and chitosan: Influence of the ionic hydrogel-forming medium." Biomaterials 24 (2003): 1459-1468.

Google Scholar, Crossref, Indexed at

5. Zhang, Mingyue, Zhiqiang Cheng, Tianqi Zhao and Mengzhu Liu, et al. "Synthesis, characterization, and swelling behaviors of salt-sensitive maize bran–poly (acrylic acid) superabsorbent hydrogel." J Agric Food Chem 62 (2014): 8867-8874.

Google Scholar, Crossref, Indexed at