Chapter 1
Chitosan-Based Biosorbents: Modifications and Application for Sequestration of PPCPs and Metals for Water Remediation

Dipali Rahangdale1, G. Archana1, Rita Dhodapkar2* and Anupama Kumar1*

1Department of Chemistry, Visvesvaraya National Institute of Technology (V.N.I.T), Nagpur, India

2Waste Water Technology Division, CSIR-National Environmental Engineering Research Institute, Nagpur, India

*Corresponding authors: anupamakumar@chm.vnit.ac.in, drkumaranupama21@gmail.com; ritadhopkar@hotmail.com

Abstract

Contamination of aquatic media by organic and inorganic pollutants is a serious environmental problem that affects the reuse of water obtained from treated domestic or industrial waste water. This chapter discusses the occurrence, persistence, bioaccumulation, adverse risk assessments on ecosystem by the pollutants along with an overview of the limitations, drawbacks, and recent challenges of some advanced effective techniques like advance oxidation processes and ozonation for the remediation of pollutants. It also highlights new horizons for their removal using new and cost-effective treatment technologies. The chapter addresses novel adsorbents including chitosan-based derivatives that have been used for sequestration of pollutants for water purification. Specific recognition sites can be incorporated within the chitosan-based biosorbents using molecularly imprinted technique for enhancing its adsorption capacity. Computer-aided design of chitosan-based biosorbents provides assistance in choice of precursors and porogen and proves to be a rapid and economical option to optimize the imprinting conditions for achieving higher removal efficiency.

Keywords: PPCPs, chitin, chitosan, grafting, adsorption, heavy metals, cross-linker

1.1 Introduction

Over the past few decades, water pollution has led to serious health effects to the flora and fauna as well as the human beings due to continuous entry of emerging pollutants and is the major environmental concern these days. It is found to be a major cause for poor nutritional standards and development in children (water pollution, Wikipedia). Pollution is caused by a variety of human activities such as industrial, agricultural, domestic as well as due to the release of untreated/treated sewage or industrial waste water to the surrounding water bodies (Ledezma et al., 2012; shen et al., 2011; Heberer et al., 2002; Jiang et al., 2013). Recent developments in analytical chemistry have led to better sensitivity and detection of compounds present in microgram or nanogram levels in water. Thus, a new group of pollutants have emerged and gained attention as these compounds end up into the aqueous environment as an upshot causing adverse effect on the living organisms as well as ecosystem. These contaminants mainly are endocrine disrupting compounds (EDCs), synthetic and naturally occurring hormones, pharmaceuticals and personal care products (PPCPs), herbicides, fungicides, pesticides, insecticides, bug repellents, etc. (Xu et al., 2013; Shraim et al., 2012; Kot-Wasik et al., 2007; Arany et al., 2013; Dodgen et al., 2014; Ziyalan et al., 2011; Pal et al., 2013).

PPCPs are diverse galaxies of chemicals defined as, compounds used in daily life for personal hygiene and cosmetic purpose as well as in agribusiness that help to enhance the growth and improve the health of livestock. Pharmaceuticals include antidepressants, tranquilizers, psychiatric drugs, cancer drugs, pain killers, anti-inflammatory, antihypertensive, antiseptics, lipid regulators (e.g., cholesterol medication), oral contraceptives, synthetic hormones, drugs for enhancing sexual performance, antibiotics, and many other classes and types of drugs. Personal care products are chemical compounds used for personal hygiene and for beautification. Personal care products include variety of compounds, such as perfumes, musk, shampoos, deodorants, hair dye, oral hygiene product, hair spray, cosmetic, nail polish, sun screen, body lotion, lipstick, etc. (Huber et al., 2003; Belgiorno et al., 2007; Molinos-Senante et al., 2014; Sun et al., 2014; Neam?u et al., 2014; Gavrilescu et al., 2015; Kosjek et al., 2012).

PPCPs are consistently entering into various aqueous sources by the discharge of treated and untreated sewage and go undetected due to no standards levied on the municipal bodies by the regulatory agencies. Persistence of PPCPs in water bodies also finds their way into the ground water and finally into drinking water. Providence and fate of PPCPs in aquatic environment is a serious matter of public concern, and recently more scrutiny has been paid to these emerging pollutants in water bodies (Ellis et al., 2006; Bolong et al., 2009; Gunnarsdottir et al., 2013). Several investigations reveals the presence of PPCPs in trace concentrations level ranging from ngL-1 to µg L-1 in various environmental matrix, possibly due to inefficacious removal by sewage treatment plants (Esplugas et al., 2007).

Many of these PPCPs are ubiquitous, persistence, and suffer biotransformation leading to the production of highly pernicious metabolites. The first alarming negative impact of the levels of PPCPs was communicated by Stumm-Zollinger in 1965 and Tabak and Bunch in 1970. Some of the negative effects caused by PPCPs include toxicity to aquatic organisms by disruption of endocrine system or genotoxicity, development of pathogenic resistant bacteria, and feminization in male fish. The recent reports on PPCPs and endocrine disruptors (EDCs) cannot be ignored due to high levels reported and at the same time these surface water bodies are source of drinking water (Sanderson et al., 2004; Escher et al., 2011; Mostofa et al., 2013; Blair et al., 2013; Bu et al., 2013; Tsui et al., 2014; Zhang et al., 2014; Kostich et al., 2014). Therefore, it is essential to remove these emerging contaminants to make the environment healthy for the survival.

The conventional treatment processes includes primary, secondary, and tertiary treatment stages, which are ineffective for the removal of PPCPs and their metabolites (Huerta-Fontela et al., 2011). Keeping the limits and draw backs of the conventional techniques, advance treatment methods like advanced oxidation processes (AOPs) have been continuously researched to resolve these problems. AOP can be considered as an effectual water operational process for remediation of most PPCPs. AOP can be defined as the oxidation process which generate very powerful hydroxyl radicals, with high oxidation potential. They are nonselective and are utilized to degrade various non biodegradable organics and inorganics. The concept of AOP was established by Glaze and coworkers in 1987. These includes homogeneous process using energy such as UV, electrical energy, ultrasound, and without energy such as H2O2 in the presence of catalyst or H2O2 in presence of ozone and heterogeneous process such as catalytic ozonation, photo catalysis, ozonation, heterogeneous catalysis, etc. Although ozonation and oxidation are considered to be effective technique, it has limitation such as high cost, likely production of toxic metabolites as well as the removal efficiency depends on the ozone dose or oxidant dose added, which limits their applicability in sewage treatment process (Kim et al., 2007; Sarkar et al., 2014; Mboula et al., 2015).

The schematic reaction for generation of OH radical in the presence of various oxidants is given below:

• H2O2 mechanism:
  H2O ·OH + H+ + e-; O2 + 2H+ + 2e- H2O2
  H2O2 HO2· + H+ + e-; HO·2 O2 + H+ + e-
• Ozonation at elevated pH:
  3O3 + OH- + H+ 2 ·OH + 4O2
• Ozonation in the presence of H2O2:
  H2O2 HO-2 + H+
  HO-2 + O3 HO2· + O-2
  HO2- + O3 HO2· + O2-
  2O3 + H2O2 2 OH + 3O2
• Fenton system (H2O2/Fe2+):
  Fe2+ + H2O2 Fe+3 + OH- + ·OH
• Ozone-UV radiation:
  O3 + hv ·O2 + O(1D)
  O(1D) + H2O H2O2 + 2 ·OH
• Photo-Fenton and Fenton-like systems:
  Fe3+ + H2O Fe(OH)2+ + H+
  Fe(OH)2+ Fe3+ + OH-
  Fe(OH)2+ Fe2+ + ·OH

Keeping these drawbacks and limitations and in view of the application of more comprehensive sewage treatment protocols as well as with the implementation of improved advance technologies, development of specific process with increased removal efficiency is required. Investigation of the effectiveness of cost-effective techniques for removal of PPCPs as an option for polishing of treated wastewater needs to be investigated.

Increase in industrial activities and uprising human population has led to increase in the heavy metals concentration in our surrounding environment which are considered toxic, as they cannot be degraded. These pollutants can enter into various water resources including surface and ground water bodies either from consumer and industrial waste or natural processes such as heavy rain which help to release the trapped heavy metals from soils. These micropollutants has ability to penetrate into the tissues and cells of various living organisms like plant, animals, and human beings...