Unveiling the Impact of Diverse Morphology of Ionic Porous Organic Polymers with Mechanistic Insight on the Ultrafast and Selective Removal of Toxic Pollutants from Water

Abstract

In recent years, detoxification of contaminated water by different types of materials has received a great deal of attention. However, lack of methodical in-depth understanding of the role of various physical properties of such materials toward improved sorption performance limits their applicable efficiencies. In perspective, decontamination of oxoanion-polluted water by porous materials with different morphologies are unexplored due to a shortfall of proper synthetic strategies. Herein, systematic optimization of sequestration performance toward efficient decontamination of toxic oxoanion-polluted water has been demonstrated by varying the morphologies of an imidazolium-based cationic polymeric network [ionic porous organic polymers (iPOP-5)]. Detailed morphological evolution showed that the chemically stable ionic polymer exhibited several morphologies such as spherical, nanotube, and flakes. Among them, the flakelike material [iPOP-5­(F)] showed ultrafast capture efficiency (up to ∼99 and >85% removal within less than 1 min) with high saturation capacities (301 and 610 mg g–1) toward chromate [Cr­(VI)] and perrhenate [Re­(VII)] oxoanions, respectively, in water. On the other hand, the spherical-shaped polymer [iPOP-5­(S)] exhibited relatively slow removal kinetics (>5 min for complete removal) toward both Cr­(VI) and Re­(VII) oxoanions. Notably, iPOP-5­(F) eliminated Cr­(VI) and Re­(VII) selectively even in the presence of excessive (∼100-fold) competing anions from both high- and low-concentration contaminated water. Further, the compound demonstrated efficient separation of those oxoanions in a wide pH range as well as in various water systems (such as potable, lake, river, sea, and tannery water) with superior regeneration ability. Moreover, as a proof of concept, a column exchange-based water treatment experiment by iPOP-5­(F) has been performed to reduce the concentration of Cr­(VI) and Re­(VII) below the WHO permitted level. Mechanistic investigation suggested that the rare in situ exfoliation of flakes into thin nanosheets helps to achieve ultrafast capture efficiency. In addition, detailed theoretical binding energy calculations were executed in order to understand such rapid, selective binding of chromate and perrhenate oxoanions with iPOP-5­(F) over other nonmetal-based anions.

Triptycene-based and imine linked porous uniform microspheres for efficient and reversible scavenging of iodine from various media: a systematic study

“…34,35 A judicious choice of monomers yields POPs in high yield via facile reactions that include but are not limited to metal catalyzed cross-coupling and condensation polymerization. [36][37][38][39][40] Among the various methodologies, Schiff base condensation is a very simple and efficient reaction to synthesize imine linked POPs that have wide applications in the elds of gas storage, catalysis, biology, energy, environmental remediation and so on. [41][42][43] A literature survey indicated that only a few imine-linked POPs have been explored to date as strategic materials for iodine capture and storage purpose.…”

Selective and Sensitive Recognition of Specific Types of Toxic Organic Pollutants with a Chemically Stable Highly Luminescent Porous Organic Polymer (POP)

“…Recently, the luminescent porous material based fluorescence technique for the detection of target-specific environmental contaminants has received special research attention, owing to its pre-concentration effect, high sensitivity, selectivity, reusability, low fabrication and operational costs, etc. − Compared to traditional porous materials, such as activated carbon, zeolites, and resin, advanced porous materials such as metal–organic frameworks (MOFs) and porous organic polymers (POPs) have recently been shown to be promising toward sensing application because of their improved sensitivity, high selectivity, and fast response. , Although several MOF-based antibiotic and pesticide sensing studies have been reported, − , the detection of these species with low-cost and thermally and chemically stable highly luminescent POPs is very rarely explored. , POPs are a class of porous materials constructed with strong covalent bonds between various pure organic building blocks as a potential scaffold, featuring highly tunable porosity and excellent chemical and thermal stability. − The successful development of such materials with the aforementioned properties along with rational incorporation of fluorophores also offers advantages toward construction of efficient sensory materials. The high porosity and large surface area of these materials allow fast mass diffusion and strong interaction of the probes with the targeted analytes and thus further result in rapid detection and sensitivity, respectively. − Moreover, the heterogeneous nature coupled with high chemical stability of these materials enables the easy and superior recyclable detection ability of these probes, making them useful for different environments. , …”

Rapid and Efficient Removal of Diverse Anionic Water Contaminants Using a Guanidium-Based Ionic Covalent Organic Network (iCON)

“…However, the rapid industrialization in recent times, to satiate the demands of the inflating population, has led to significant exploitation of this crucial natural resource. − Therefore, the remediation of contaminated water has attracted worldwide attention . Scientific research indicates that anthropogenic water pollutants consist of organic as well as inorganic chemical species that are released into the environment owing to human activity. − These pollutants comprise various species that include but are not limited to pharmaceutical products, herbicides/pesticides, organic dyes, toxic metal ions, and radioactive species, which find their way into the ecosystem. − …”