Indian Institute of Science Education and Research (IISERB) Bhopal researchers have developed organic polymers that can remove highly polar organic micropollutants (POMs) from water. This process will render the water safer for human consumption.
These polymers have already been tested for polar organic micropollutants removal at a laboratory scale. Large-scale fabrication of these materials in collaboration with industrial partners will open up a promising avenue for real-time scavenging of toxic polar organic micropollutants from water.
Called ‘Hyper-crosslinked Porous Organic Polymers’ (HPOPs), a teaspoon of the powder of these polymers will cover an internal surface area of 1,000-2,000 m2/g, which is close to 10 tennis courts.
The Research was led by Dr. Abhijit Patra, Associate Professor, Department of Chemistry, IISER Bhopal, at the Functional Materials Laboratory of the Institute.
The Team comprised Arkaprabha Giri, Ph.D. student, Department of Chemistry, IISER Bhopal, Subha Biswas, former BS-MS student of Department of Chemistry, IISER Bhopal, currently pursuing Ph.D. at IISc Bangalore, Dr. MD. Waseem Hussain, former Ph.D. student of Department of Chemistry, IISER Bhopal, currently, pursuing post-doctoral research at Hanyang University, South Korea, Tapas Kumar Dutta, Ph.D. student, Department of Chemistry, IISER Bhopal.
IISERB organic polymers research requirements
Highlighting the critical need for such Research, lead author Mr. Arkaprabha Giri, Ph.D. Student, Department of Chemistry, IISER Bhopal, and Dr. Abhijit Patra, Associate Professor, Department of Chemistry, IISER Bhopal, said, “In India, the prime concern is water contamination due to anthropogenic waste discharged to surface and groundwater by domestic, agricultural, and industrial sectors.
These wastes contain large numbers of organic/inorganic micropollutants. Organic micropollutants are a diverse set of ‘analytes’ whose presence in water, even in trace amounts, pose a serious threat to human health and aquatic lives.”
Dr. Abhijit Patra added, “A process called ‘Sorption’ is one of the most energy-efficient techniques to purify water from organic micropollutants. However, commonly-used carbonaceous adsorbents possess several bottlenecks, such as a slow uptake rate and a tedious regeneration process.
Therefore, we need efficient adsorbent materials that can not only scavenge highly polar organic micropollutants (POMs) from water rapidly but also can be synthesized easily on a large-scale through simple fabrication techniques.
This was the problem the IISER Bhopal Researchers at Functional Materials Laboratory set out to tackle.”
Micropollutants removable by Hyper-crosslinked Porous Organic Polymers (HPOPs)
The following are some of the most common organic micropollutants discovered in surface water:
- Pharmaceuticals such as Antibiotics and steroid
- Industrial Chemicals including Dyes, food additives, endocrine disruptors, and plastic precursors
- Agricultural wastes such as Pesticides, Herbicides and Fertilizers.
Researchers at the Functional Materials Laboratory in IISER Bhopal developed a series of organic polymers called ‘Hyper-crosslinked Porous Organic Polymers’ (HPOPs) with distinct morphologies (spherical nanoparticles to the two-dimensional nanosheets) using paddle wheel-like aromatic monomer, triptycene, by varying the synthetic conditions.
Knitting triptycene units with halogen-containing organic solvent (dichloromethane) using a simple and cheap catalyst, anhydrous aluminium chloride, led to the HPOP with 2D sheet-like morphology having a remarkably high surface area of 2,400 m2/g.
This solvent knitted HPOP contains numerous numbers of tiny pores (a few nanometers; 1 lakh times smaller than the cross-section of a human hair).
As a result, the 2D sheet-like HPOP can act as a sponge for the adsorption of various organic micropollutants from water.
Further, the researchers followed the ‘same likes same’ design strategy by decorating the walls of the tiny pores of the highly porous 2D sheets with polar functionalities (sulfonic acid group) to enhance the adsorption capacity and easy sequestration of highly polar organic micropollutants (POMs) from water.
The researchers showed, for the first time, the evolution process of 2D nanosheets of solvent knitted HPOP from nanospheres to nanoribbons to 2D nanosheets through electron microscopy.
The adsorption rate for toxic cationic dye, methylene blue (carcinogenic, teratogenic, mutagenic) by solvent knitted HPOP is one of the highest among the well-known adsorbent materials reported in the literature (17.6 g mg-1 min-1).
The 2D sheet-like HPOP could sequester a broad-spectrum of POMs, including antibiotics, endocrine disruptors, steroid-based drugs, ionic dyes, plastic precursors, pesticides, and herbicides within 30 seconds only.