Water is the most important compound for life on earth and it is a major global challenge for the 21st century to have drinkable water. Though more than 71% of the earth surface is covered with water, but only less than 1% water is drinkable as per international standards because of different contaminations. An unacceptably large portion of the world population— one person in five—does not have access to safe and affordable drinking water. Nearly 33 countries expected to face extremely high water stress by 2040. The main sources of water contamination include waste water discharge from industries, agricultural activities, municipal wastewater, environmental and global changes. Water recycling has proven to be effective and successful in creating a new and reliable water supply without compromising public health. Various remediation technologies have been developed for the removal of pollutants including toxic heavy metals, dyes, pesticides, fertilizers, organic acids, and halogenated and phenolic compounds, among others. Techniques such as precipitation, incineration, flocculation, coagulation, ion exchange, reverse osmosis, membrane filtration, electrochemistry, photo electrochemistry, advanced oxidation processes, and biological methods have demonstrated different degrees of remediation efficiency. Advances in wastewater treatment technology and health studies of indirect potable reuse have led many to predict that planned indirect potable reuse will soon become more common. Recycling waste water requires far less energy than treating salt water using a desalination system. As water energy demands and environmental needs grow, water recycling will play a greater role in our overall water supply. In addition to providing a dependable, locally-controlled water supply, water recycling provides tremendous environmental benefits. By providing an additional source of water, water recycling can help us find ways to decrease the diversion of water from sensitive ecosystems. Other benefits include decreasing wastewater discharges and reducing and preventing pollution. While water recycling is a sustainable approach and can be cost-effective in the long term, the treatment of wastewater for reuse and the installation of distribution systems at centralized facilities can be initially expensive compared to such water supply alternatives as imported water, ground water, or the use of gray water onsite from homes. In the present era of scarcity of water resources, effective treatment of wastewater is a major prerequisite for growing economy. It is critical to develop and implement advanced wastewater treatment technologies with high efficiency and affordable price. 

Several modern technologies have benefited from novel multi-functional materials. In this regard, porous organic polymers (POPs) are a promising class because of their ultrahigh hydrothermal stabilities, light weight, and high yielding synthetic polymer chemistry.1 Calix[n]arenes (n = 4, 6, 8) have long been recognized as versatile supramolecular scaffolds, however, we are the first to report a calixa[n]arene based porous polymers.2 Building on these findings, we synthesized library of calixarene based porous materials with BET surface areas ranged from 500 to 1000 m2 g-1. Our design strategy has been ranging from amorphous 3D-polymers to 2D-nanosheets, and then evolved toward ordered polymeric materials. Lately, we have been working on the development of smart materials with specific application in mind. So far, these materials have been tested for multiple applications including 1) oil spill recovery,2 2) toxic dyes2,3 and micropollutants removal,4 3) iodine enrichment,5,6 and 4) paraquat and mercury removal,7 My talk will highlight the development of this fascinating series of polymers and their superior efficiency over existing materials.