Nanohybrid Materials for Water Purification

Water is indispensable for entire existing life forms of the Universe. Being the backbone for climate change and pivotal for economic, social and energy development in every respect, the management of water resource should be the premier responsibility for all human beings. Reduction of water quality due to natural and man-made pollution and failures of conventional water treatments for purification of water can frequently lead to many contamination incidents resulting serious disease outbreaks. Recently, nanohybrid materials attracted attentions of researchers to design and develop many purification techniques by nanohybrid materials adopting different approaches such as removal and sensing of dyes, heavy metals and oily wastes, desalination, antifouling agent, designing of nano-membranes, magnetic, catalytic and photocatalytic nanohybrid materials. This chapter delineated in words and pictures about many important facts and terms related to water along with the sources, effects, and prevention of water pollution by conventional and the present fashions by nanohybrid materials. Ultra-modern outfits for wastewater treatment by nanohybrid materials are environment friendly, low cost and effective for the capitalization purpose.

Nanohybrid materials or nanocomposites are a special class of new age advanced materials that have gained wide scale popularity because of their multifunctionalities. The nanocomposites offer a set of unique and outstanding properties like biodegradability, flexibility, processibility, good mechanical properties, and optical properties. The history of materials is established starting from stone age to present stage. Present chapter reveals an overall idea regarding the introduction to nanohybrid materials.

Water is a precious natural resource and its quality and availability is essential for the survival of living creatures on the earth. However, rapid industrialization is continuously degrading the quality of water due to the incontrolable discharge of large amounts of pollutants into the water bodies. Water pollutants have appeared as threats for the entire biosphere, so their removal has become essential. The different types of water pollutants along with their sources and impact are ellucidated. The fundamental requirements for water purification are appropriate materials with high separation capacity, low cost, porosity, and reusability. Taking this into consideration, nanotechnology provides an opportunity to develop advanced materials for effective water purification by optimizing their properties like hydrophillicity, hydrophobicity, porosity, mechanical strength, and dispersibility. Nanoparticles having high surface area, can contribute a lot in water purification but its agglomeration restricts its use. However, agglomeration can be minimized by converting nanomaterials to nanocomposites. In this chapter, different types of nanocomposites, their preparation and properties are discussed.

The pollution of water by potentially dyes, is severe form of environmental impact. Traditional wastewater treatment are inadequate and cannot encounter the basic standards of water quality at sensible cost or processing time. Removal of dyes from aquatic surroundings has become a main alarm due to environmental problems and the possible hazards and hazards posed by them. Nowadays, the adsorption method as one of the most effective methods of eliminating pollutants has fascinated growing consideration among chemists and environmental researchers. However, one of the tasks is to design more effective adsorbents besides preparing them via greener and safer approaches. Nanocomposites are considered talented materials for the removal of potentially toxic dyes from aqueous solution through adsorption process. The present chapter deals with the utilization of nanocomposites for removal of dyes.

It is well known that water is an essential component for sustaining life and most human activities. The problem of water pollution has been a constant threat worldwide. Several human and industrial activities release uncountable pollutants into the water sources, most toxic and even fatal to plants and animals. Among these pollutants, dyes are the common pollutants responsible for hindered grown of plants and cancer in human beings. As scientists are aware of these threats, they proposed various methods to remove dyes from wastewater. Several physical, chemical, and biological treatment methods are proposed to remove dyes. With the development of nanocomposites and their excellent capabilities for adsorption and photocatalytic degradation, they have been proposed as suitable materials for dye removal. Nanocomposites are composed of two or more materials; one acts as a base material in which other materials are incorporated. Today, many nanocomposites have been known to display outstanding efficiencies to remove dyes from wastewater, some of which are reviewed in this work. Herein, we present the recent advances in nanocomposite materials with high efficiencies for the removal of some toxic dyes from wastewater. The mechanism of adsorption and photocatalytic degradation is presented. Furthermore, the scope of future research is also discussed.

Polymer grafted nanocomposites have received high attentions from researchers for their versatile applications and amazing properties. The process of overcoming the contamination of water is one of the important application of nanocomposites prepared from polymer grafted matrix with reinforcement of nanostructurted materials. This chapter comprises of two impressive aspects. The difference between designing a polymer nanocomposite and polymer grafted nanocomposite and the eye catching changes in properties and applications by introducing grafting technique to polymeric nanohybrid materials is the first primary attraction of the present chapter. Secondly, by accounting the important exposure towards water treatment by different polymer grafted nanohybrid materials, this chapter gives a clear purpose for designing more potential polymer grafted nanohybrid materials by reaching the needs of the book. Different grafting mechanisms, along with the photocatalytic mechanism shown by polymer grafted nanohybrid materials are discussed. Dye adsorption, removal of metal ions, desalination of salt water and the antifouling behaviour of polymer grafted nanohybrid materials and membranes are detailed.

Nanohybrid based polymeric membranes technology for water purification and separation have grown over the years associated to its advancement in the past decades and remarkable impact to the membrane characteristics and performance is encouraging. In this chapter, the progress of the nanohybrid based polymeric membranes for water-based application was divided into two major sections namely membrane technology and nanohybrid polymeric membranes. The membrane technology discussed on the pressure driven membrane process, membrane configuration, membrane fabrication, membrane materials and types of membranes while the latter part discussed on graphene oxide based and non-graphene nanohybrid based polymeric membrane for water purification and separation.

In recent years, the constant population growth worldwide has put pressure on the need for clean and safe water for human consumption. Magnetic nanomaterials (MNMs) have emerged as a promising material in the past few decades due to their unique physiochemical properties. MNMs possess the desired characteristics for their application in water purification. However, it is important to develop well defined magnetic nanomaterials for efficient removal of water pollutants. This requires effective synthetic methods for the synthesis of shape, size and morphology-controlled nanomaterials. Various physical, chemical and biological methods including ball milling, gas phase deposition, thermal decomposition, hydrothermal, solvothermal, co-precipitation, sol–gel, etc. have been explored over the years for their synthesis. The presence of organic and inorganic pollutants in water even in trace concentration has extreme adverse effects on human and environmental health. Hence, it is the need of the hour to develop effective and economical methods for application in water remediation. In this chapter, the problem of water pollutants, their threatening effects and the use of MNMs in water purification have been addressed. These MNMs are characterized using methods such as UV, IR, XPS, XRD, SEM, TEM, VSM, AFM, RS, ¹HNMR, etc. Finally, the application of these materials for water purification have been discussed in detail—highlighting the removal of pesticides, dyes, pharmaceutical drugs, inorganic anions, heavy metals and oil spill from water.

The accessibility of safe drinking water is currently a critical concern; the challenge is to develop an effective method to remove pollutants to ultra-low levels and recycle wastewater through purification. Among the water purification methods that have already been employed, nanotechnology has been considered the most promising method. This is because the nanomaterials used as adsorbents have been proven to remove different classes of pollutants, including emerging water pollutants, and these nanomaterials can be regenerated and reused. Particularly carbon nanotubes-based polymeric nanocomposite materials have attracted significant research attention because they possess multifunctional properties helpful in removing different types of pollutants from wastewater. Therefore, this chapter reviews recent studies reported on carbon nanotubes modified with natural polymers (biopolymers) such as chitosan, cellulose, and cyclodextrin used in water treatment. The cost and economic value of carbon nanotubes modified with polymeric hybrid materials used as nano-sorbents for water purification are also discussed.

Now a days, water contamination, caused by the presence of synthetic dyes and heavy metal pollutants, is recognized as the potential threat to the human civilization. These toxic chemicals are sufficient to attribute severe health issues even in a very low consumption due to their carcinogenic and mutagenic behaviors. Moreover, these chemicals are nonbiodegradable with high tendency of bioaccumulation and hence, need to be removed from the main-stream water bodies prior to entering the food chain. Among various separation/removal techniques, adsorption through the polymer nanocomposites, is regarded as the easiest and cost-effective way to deal with the water pollution. Chitosan is a pseudo-natural cationic polysaccharide, obtained largely from various natural sources. Because of its high surface functionality (amine and hydroxyl groups), biocompatibility and non-toxic nature, this gel-forming polymer is highly preferred in preparing nanohybrid adsorbent. This book chapter mainly provides an insight into the chitosan nanohybrid structures used for the removal of a variety of different dyes and heavy-metal pollutants.

Clean water is very important for living being and other activities. However, water is continually being polluted and become harmful. Number of techniques is being used for purification of water and out of that adsorption is found to be the most affordable and fast technique. In recent years, nanotechnology has played an important role in water purification and decontamination. Nanomaterials (NMs) have proved to be a very good adsorbent for the removal of organic and inorganic pollutants and heavy metals from water and also kill microorganisms in the wastewater. Due to electronic structure, electronic, optical, and magnetic properties, metal oxide nanoparticle (NPs) are found to be unique materials for water remediation. Metal oxide-based NMs, such as zinc oxides, iron oxides, manganese oxides, titanium oxides, aluminum oxides, magnesium oxides, cerium oxides, zirconium oxides, etc. have shown their effectiveness for water remediation. Nanosized metal oxides possess many exceptional properties, such as a high removal capacity and selectivity towards heavy metals and organic compounds. Thus, they have great potential as promising adsorbents for heavy metals, dyes and other pollutants. In this chapter synthesis of number of metal oxide NMs and their applications for water decontaminations have been discussed in detail.

Core–shell nanoparticles have been the centre of attention of the researchers in various fields as the transition from bulk/micro particles to nanoparticles to core shell nanoparticles was seen to lead to enormous changes in the physical and chemical properties of the materials like increased surface to volume ratio, dominance of surface atoms over those in the core etc. Core–shell nanohybrid structures are nanocomposites which incorporates the advantages of both core–shell nanoparticles and other component of the hybrid material like polymer, ceramic, oxide structures. In recent times core–shell nanohybrid structures have gained wide attention in different energy and environment applications including sorption of pollutants from aquatic medium. Drinking water pollution is one of the major problems the world is facing today. Various technologies have been developed for removal of various contaminants from aquatic streams. Core–shell hybrid nanostructures can be tailored by chemical modification or by incorporation in the polymeric matrix. This not only makes them specific to some metal ions, radionuclides even nanoparticles but also enhances their sorption capacity. These materials can be synthesised by dispersion of building blocks in polymeric network, in situ polymerisation, sol–gel process, self-assembly of unit building blocks through layered structures or interpenetrating networks. In this book chapter, a series of core shell nanohybrid structures having application in water decontamination have been reviewed and discussedextensively. Synthesis strategies, sorptive properties of these core shell nanohybrid structures are summarised with emphasis on decontamination of conventional pollutants, radionuclides, dyes and organic pollutants.

One of the main emerged trends in the water purification sector is hybrid materials adoption. Due to their peculiarity of combining several components into one formulation, hybrid materials are effective in removing a panoply of pollutants from contaminated water. Thereby, they provide a conceivable alternate to conventional water purification. Nevertheless, considerable challenges are remaining in the industrial process scale-up, including, stability, lifecycle, sustainability, and cost-effectiveness. The main objective of this book chapter is to allow scrutiny and gain an appropriate understanding of future perspectives and challenges faced by hybrid materials, for the simple reason that a proper understanding of the challenges will add to the understanding of measures to be taken.