Performance and Isotherm Studies in Phenol Adsorption From Wastewater Using Low Cost Biomass Derived From Coconut Shells

Performance and Isotherm Studies in Phenol Adsorption From Wastewater Using Low Cost Biomass Derived From Coconut Shells

Mohan Rao T. (Debre Berhan University, Ethiopia), K. Rajesh Kumar (SR Engineering College, India), G. Shyamala (SR Engineering College, India) and R. Gobinath (SR Engineering College, India)
DOI: 10.4018/IJCCE.2019070103

Abstract

With the growth of urbanization and industrialization, water bodies are getting polluted. Among various pollutants, phenol-based pollutants are common water pollutions which originate from wastewater discharged from processing manufacturing industries like petrochemical refineries, ceramic plants, textile processing, leather processing, synthetic rubbers, etc. These pollutants are toxic and have long-term ill effects on both humans and aquatic animals. Adsorption is well proven technique which is widely used for removal of pollutions from aqueous environments. But this process, is hindered due to the cost of adsorbents especially for large scale continuous processes. In this regard, adsorbents derived from waste biomass can be a great asset to reduce the cost of wastewater treatment. To meet this objective, coconut shells are chosen as biomass which is abundantly available from south east Asia. This biomass is converted into activated carbon and hence used to remove phenol from wastewater. Batch adsorption experiments were performed with different initial concentration, carbon dosage, pH and contact time. At a lower concentration of 50 mg/L of initial feed (phenol) concentration resulted in around 90% phenol removal and henceforth optimum results in phenol removal obtained in only 64%. Experimental results are in good agreement with Langmuir adsorption isotherm model and have shown a better fitting to the experimental data. These studies confirm that the coconut shell-based activated carbon could be used to effectively adsorb phenol from aqueous solutions.
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1. Introduction

Phenol is a colourless, hygroscopic and crystalline substance, which turns pink in air owing to its oxidation. It is a derivative of benzene, is an important raw material and/or product of chemical and allied industries (e.g. petrochemicals, oil refineries, plastics, leather, paint, pharmaceutical, steel industries, pesticides, antiseptics, dyes, antirust products, synthetic resins, biocides, photographic chemicals, ink, varnishes, etc.) (Kujawski et al., 2004; Adak et al., 2006). Phenol includes a variety of hydroxybenzenes and substituted hydroxybenzenes. These are common water pollutants. The major sources containing phenols are the wastewaters from processing manufacturing industries engaged in oil refining, coal tar processing, petrochemical production, coke oven byproducts, plastic industry, ceramic plants, textile processing, leather processing, synthetic rubber processing, pesticides & insecticides production, manufacture of dyes and dyeing, pharmaceutical, steel industries, glass production, phenolic resin industries etc. (Singh et al., 2008; Goud et al., 2005; Mohanty et al., 2008).

Phenolic compounds are water soluble and highly mobile and hence are likely to reach drinking water sources downstream from discharges, where, even at low concentrations, they can cause severe odour and taste problems and pose risks to populations. Phenols may also come to the environment through the agricultural runoff and domestic waste (Burleigh et al., 2002; Hairuddin et al., 2019; Karri et al., 2017; Karri et al., 2017). Chronic toxic effects due to phenols reported in humans include vomiting, difficulty in swallowing, anorexia, liver and kidney damage, headache, fainting and other mental disturbances. That phenol is highly toxic and difficult to degrade biologically have led to setting up of rigid limits on the acceptable level of phenol in the environment. According to the recommendation of World Health Organization (WHO), the permissible concentration of phenolic contents in potable waters is 1 μg L−1 (Schulze, 1986) and the regulations by the Environmental Protection Agency (EPA), call for lowering phenol content in wastewaters less than 1 mg L−1 (Dutta et al., 1998).

The presence of phenols and phenolic compounds in wastewater is a major problem for adverse effects on aquatic life and stringent environmental regulations attracts the attention of chemists and environmental engineers for its control (Shyamala, 2016; Shayamala, 2017; Ayawei et al., 2015; Theivarasu & Mylsamy 2011). Therefore, removal of phenols from waters and wastewaters is an important issue in order to protect public health and environment.

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