Performance of Chitosan Micro/Nanoparticles to Remove Hexavalent Chromium From Residual Water

Hexavalent chromium Cr(VI) is toxic to living systems and must be removed from wastewater. Chitosan is a cationic, biocompatible, biodegradable, biopolymer obtained from marine wastes. The performance of chitosan particles (CH) and chitosan nanoparticles (CHN) to remove Cr(VI) from aqueous solutions is discussed in the present chapter. CHN were obtained by reticulation with tripolyphosphate (TPP), and physico-chemically characterized. The performance of CHN decreased at higher pH due to the cross-linking process with TPP. Langmuir isotherm described the equilibrium adsorption values and pseudo-second order rate provided the best fitting to the kinetic data. Chemical analysis to determine the oxidation state of the adsorbed Cr, showed that Cr(VI) was adsorbed on CH particles without further reduction; in contrast Cr(VI) removed from the solution was reduced and bound to the CHN as Cr(III). Chitosan crosslinking was essential to adsorb Cr(VI) at pH<3 due to the dissolution of CH in acid media.

Characteristics of Chitosan Nanoparticles for Water and Wastewater Treatment

Chitosan is a naturally occurring biopolymer originating from several microbial species as well as crustacean species, such as shrimp and lobster. Chitosan has excellent physical and chemical properties that allow its use in various environmental applications especially in water treatment. It is a biodegradable polymer, and it is inexpensive providing an environmentally friendly and economic option for water and wastewater treatment. Chitosan offers a myriad of applications through chemical coagulation and flocculation, antimicrobial properties, adsorption capabilities, and nanofiltration and can provide a sustainable route for water and wastewater treatment. This book chapter elaborates the recent developments in chitosan applications in water and wastewater treatment.

Advanced Nanomaterials for Water Engineering and Treatment

Loading of water with multifarious pollutants has dwindled the availability of quality fresh water and put questions on reliability and efficacy of conventional water treatment technologies. Also the quest for developing robust and cost-effective methods with minimum impact on environment had driven the focus of researchers and technologists on new technological developments. Nanotechnology – better referred as Aqua-nanotechnology in this regard provides scientists a new dimension to deal this big problem with small particles having application in 1) water treatment, 2) remediation, and 3) pollution prevention. This chapter will focus on fabrication and use of advance nanomaterials categorized as nanoadsorbents and nanoatalysts for these three main areas. A range of materials exploited in this regard are single and mixed metal oxides and their composites with polymer, clay, carbon based materials etc. while keeping focus on technological developments taken place over the period in regard with treating water and waste water.

Polymer Consumption, Environmental Concerns, Possible Disposal Options, and Recycling for Water Treatment

The increasing awareness of the environment has raised so much concerns in the way we live and the manner to which we dispose our waste. The rapid growth in polymer production has resulted in increasing concerns about the consumption of nonrenewable resources and the environmental impacts associated with its production and disposal. Polymer waste is one of the major components in municipal solid waste and is increasingly becoming a huge burden in industrialized nations. The rise in the use of plastic, coupled with increasing concerns about its disposal, has led to a renewed interest in its recycling and recovery. The technologies involved in the recovery and recycling of polymers are rapidly growing, however, there is no specific pattern of treating polymer waste. The technology depends on the type of material used in the production and consumption pattern. This chapter, therefore, discusses the patterns of polymer consumption, the environmental concerns, and different modes of recycling polymer waste.

Fundamentals and Sources of Magnetic Nanocomposites and Their Sorption Properties

Over the years, adsorption has been the most widely applied technique for pollutants remediation in conventional water and wastewater treatment regimes with commendable results. Consequently, multiple adsorbents have been synthesized, characterized and tested for various pollutants sequestration such as; heavy metals, dyes, pharmaceutically active ingredients, among others, in aqueous media. Unfortunately, most of the sorbents face many inherent limitations such as high production cost, difficult separation of adsorbent from solution, and complex synthesis processes. Therefore, an efficient adsorbent that would be sustainably adopted for industrial application in wastewater treatment requires, among other properties, a simple and efficient recovery step from a continuous flowing system. The regenerated adsorbent must also possess near original properties after several cycles of reuse thereby resulting to low capital investment. To address this challenge, studies conducted in the past few years incorporating magnetism in both natural and synthetic sorbents to improve their removal from water via magnetic separation have yielded stupendous results compared to conventional technologies. This chapter concisely discusses synthesis methods and adsorption capacities and mechanisms of selected magnetic nanocomposite adsorbents under diverse physicochemical conditions for removal of cations, dyes and organic pollutants from wastewater. Magnetic nanocomposites present eco-friendly properties and are potential alternatives for application in water purification processes subject to commercial viability evaluation before practical use.

Principles and Advantages of Microwave-Assisted Methods for the Synthesis of Nanomaterials for Water Purification

Nanomaterials are the pillars of nanoscience and nanotechnology and to realize their full potential in various potential applications, synthetic methodologies/routes need to be established that are simple, fast and cost-effective. Wet-chemical approaches for nanomaterial synthesis have proven to be among the most versatile and effective routes to finely tailor nanocrystals with varying compositional and architectural complexity. Microwave-assisted solution route represents an efficient wet-chemical approach for the synthesis of nanomaterials that offers additional advantages, such as rapid volumetric heating, high reaction rates, size and shape control by tuning reaction parameters, and energy efficiency. In addition, the homogenous heating of the reactants in microwave synthesis minimizes thermal gradients and provides uniform nucleation and growth conditions that leads to the formation of nanomaterials with uniform size distribution. This chapter deals with the basics of microwave chemistry and its applications towards the synthesis of nanomaterials for catalytic applications.

Applications of Nanomaterials for Water Treatment

Development of new technologies, progressive urbanization, increasing consumerism and industrial boom in developing countries has led to elevated pollution of the environment. The spectrum of pollutants produced and released to the environment has increased in the last few decades including the agricultural, industrial, pharmaceutical and plastic industries. In the developed and underdeveloped countries where environmental pollution goes on increasing day by day, the concern of mankind to the threat of humanity increases which comes from anthropogenic degradation of the environment. An analytical chemist is always in search of cheaper, quicker, more sensitive, more reliable, precise methods of analysis. To achieve such a goal many properties of the materials are studied. Nanotechnology meets many of the conditions mentioned above and is very economic. So, analytical nanotechnology is an important tool for preconcentration and separation of pollutants at low levels.

Biomass-Derived Activated Carbon

The focus is to highlight the catalytic technologies to convert lignocellulosic biomass into the activated carbon (AC) which can be used in photocatalysis applications. The drawback of carbon production raised by energy assumption and product selectivity has encouraged the development of sustainable carbon synthesis process, where the catalytic approach is considered. This treatment via either homogenous or heterogeneous catalytic approach relative in mild condition provided a bulk, mesoporous and nanostructure AC materials. Those characteristics of AC materials are basic requirements for the efficient photocatalytic system. Due to the excellent oxidizing behavior and stability, semiconductor materials have been widely used in the photocatalytic system. However, they lead to some drawbacks in terms of the separation steps and loss of the photocatalyst. So, attention has been paid to supported semiconductor catalysts which carbon materials were explored. AC reported as a potential support in photocatalytic systems.

Advanced Nanomaterials for the Removal of Chemical Substances and Microbes From Contaminated and Waste Water

The development of cost-effective, efficient and stable materials helps to provide the affordable solutions to get safe and fresh water to increasing population with health guidelines of emerging contaminants. Nanomaterials (NMs)-based techniques involve the design, synthesis, manipulation, characterization and exploitation of materials for adsorption and separation of target species from the contaminated and waste water. NMs show better adsorption capacity and catalytic for number chemical species and microbes because of their small size and large surface area that favors the purification and treatment of waste or contaminated environmental water. Here, we present the chemical properties, adsorption/removal mechanism and applications of advanced NMs such as magnetic nanoparticles (MNPs), carbon nanotubes (CNTs), graphene and graphene oxide (GO), titanium oxide (TiO2), silica (SiO2), silver (Ag), gold (Au) NPs and zeolites in effective and efficient removal of toxic metal ions, organic and inorganic chemical substances and disease-causing microbes from contaminated and wastewater.

Scientific Insights Into Modified and Non-Modified Biomaterials for Sorption of Heavy Metals From Water

Adsorption techniques are widely used for the removal of various classes of pollutants from water due to their mild and facile operating conditions. The operations involved in the adsorption techniques are environmentally friendly, economical, highly selective on pollutants, highly efficient and easily operative. However, the adsorption of heavy metals from water using biomaterials (biosorption) is a relatively new and interesting technique which holds a great potential. Its effectiveness in lowering the heavy metals concentration to sub-ppb levels is appealing and has attracted increasing attention. The technique is believed to replace the existing technologies in the near future. This chapter discusses the prospects of biomaterials in the removal of heavy metals from waste water, the modification techniques that can enhance biosorption efficiency, and the factors influencing the biosorption processes.