CHARACTERIZATION AND UTILIZATION OF ACTIVATED TAMARIND KERNEL

CHARACTERIZATION AND UTILIZATION OF ACTIVATED TAMARIND KERNEL

ABSTRACT

Activated tamarind kernel powder was prepared from tamarind seed(Tamarindus indica);and utilized for the removal of Acid Red 1, Reactive Orange 20 and Reactive blue 29 dyes from their aqueous solutions. The powder was activated using 4M nitric acid (HNO₃). The effect of various parameters which include; pH, adsorbent dosage, ion concentration, and contact time were studied to identify the adsorption capacity of the activated tamarind kernel powder under the above conditions. The percentage of dye adsorbed is seen to be dependent on these factors. The result obtained indicated that the adsorption of Acid Red 1 (AR1), Reactive Orange 20 (RO20) and Reactive Blue 29 (RB29) decreased with increase in initial concentration but increased with increase in temperature. At equilibrium, all three dyes showed highest dye uptake at initial dye concentration of 20 mg/l, pH 2, adsorbent dose of 1.0 g, and at a contact time range of 80-100 min. The Langmuir, Freundlich, Temkin and Dubinin Radushkevichisotherm models measured at a temperature range of 298-328K are fitted into the graphs. The Temkin isotherm model is best-fitted into the experimental data with R² values ranging between 0.913-0.987 for Acid Red 1, 0.865-0.969 for Reactive Orange 20 and 0.942-0.992 for Reactive Blue 29. The next in line for best fitting is the Langmuir isotherm with R² values ranging between 0.859-0.995 for Acid Red 1 dye, 0.825-0.974 for Reactive Orange 20 and 0.971-0.989 for Reactive Blue 29. This is followed by Dubinin Radushkevich isotherm with R² values ranging between 0.931-0.974 for Acid Red 1, 0.923-0.989 for Reactive Orange 20 and 0.789-0.923 for Reactive Blue 29. Lastly is the Freundlich isotherm with R² values ranging between 0.803-0.931 for Acid Red 1, 0.856-0.964 for Reactive Orange 20 and 0.982-0.995 for Reactive Blue 29. The pseudo-first order and pseudo-second order kinetic models were also fitted into the graphs, but pseudo-second order was best fitted into the experimental data. The thermodynamic parameters such as enthalpy, entropy,andfreeenergywhichweredeterminedusingtheVan‘tHoffequationswerefoundto

provide the clues necessary to predict the nature of the adsorption process. The values of the activation energy (E_A) obtained indicated that the adsorption of AR1, RO20 and RB29 on activated tamarind kernel powder (ATKP) is a physical process.The negative free energy (ΔG) indicatedthat the adsorption process is feasible and spontaneous, the negative enthalpy (ΔH) indicatedthat the reaction is exothermic in nature and the negative entropy (ΔS) indicated that there is decreased randomness at the solid/solution interphase during the adsorption process. The chemical functional groups of the ATKP adsorbent were studied by Fourier Transform Infrared (FTIR) spectroscopy which helped in the identification of possible adsorption sites on the adsorbent surface. Characterization of the activated tamarind kernel powder which was carried out using standard methods, showed that the values of the parameters of interest such as moisture and dry matter content, ash content, pH and bulk density; fall within acceptable range. Therefore, activated tamarind kernel powder has proven to be a very good adsorbent for the removal of acid dyes and reactive dyes.

CHAPTER ONE INTRODUCTION

1.1               Background of Study

Environmental pollution control is said to be a matter of utmost concern in many countries. However, air and water pollution constitute the major environmental pollution in several countries. Consequently, open burning leads to air pollution, while industrial effluent and domestic sewage leads to water pollution. Water pollution results to bad effects on public water supplies which can cause health problem, while air pollution can cause lung diseases, burning eyes, cough, and chest tightness. The environmental issues surrounding the presence of colour in effluent is a continuous problem for dye stuff manufacturers, dyers, finishers, and water companies (Kesari etal., 2011).

The contaminants such as dyes, heavy metal, cyanide, toxic organics, nitrogen, phosphorus, phenols, suspended solids, colour, and turbidity from industries and untreated sewage sludge from domestics, are becoming of great concern to the environmental and public health. Therefore, the treatment of these pollutants is very important (Cheremisinoff, 1993).

Residual dyes from different sources (e.g., textile industries, paper and pulp industries, dye and dye intermediates industries, pharmaceutical industries, tannery, and Kraft bleaching industries and others) are considered a wide variety of organic pollutants introduced into the natural water resources or wastewater treatment systems. One of the main sources with severe pollution problems worldwide is the textile industry and its dye-containing wastewaters (i.e. 10,000 different textile dyes with an estimated annual production of 7.105 metric tonnes are commercially available worldwide; 30% of these dyes are used in excess of 1,000 tonnes per annum, and 90% of the textile products are used at the level of 100 tonnes per annum or less) (Baban et al., 2010; Robinson et al., 2001; Soloman et al., 2009). About 10-25% of textile dyes are lost during the dyeing process, and 2-20% is directly discharged as aqueous effluents

in different environmental components. In particular, the discharge of dye-containing effluents into the water environment is undesirable, not only because of their colour, but also because many of the dyes released and their breakdown products are toxic, carcinogenic or mutagenic to life forms mainly because of carcinogens, such as benzidine, naphthalene and other aromatic compounds (Suteu et al., 2009; Zaharia et al., 2009). Without adequate treatment these dyes can remain in the environment for a long period of time. For instance, the half-life of hydrolysed Reactive Blue 19 is about 46 years at pH 7 and 298 K (Haoet al., 2000).

In addition to the aforementioned problems, the textile industry consumes large amounts of potable and industrial water as processing water (90-94%) and a relatively low percentage as cooling water (6-10%) in comparison with the chemical industry where only 20% is used as process water and the rest for cooling. The recycling of treated wastewater has been recommended due to the high levels of contamination in dyeing and finishing processes (i.e. dyes and their breakdown products, pigments, dyeintermediates, auxiliary chemicals and heavy metals, and others(Bertea and Bertea, 2008; Bisschops and Spanjers, 2003; Correia et al., 1994; Orhon et al., 2001).

Synthetic dyes have been increasing in textile industries for dyeing natural and synthetic fibres. Discharge of dye- bearing waste-water makes an adverse effect on aquatic environment because the dyes give water undesirable colour (Ibrahim et al., 2010) and reduce light penetration and photosynthesis (Al-Degs et al., 2004; Wang et al., 2005; Oei et al., 2009). Conventional methods used to treat coloured effluents are oxidation, coagulation and flocculation, biological treatment, membrane filtration. However, the single conventional treatment is unable to remove certain forms of colour, particularly those arising from reactive dyes as a result of their high solubility and low biodegradability (Vijayaraghavan et al., 2009).

1.2               Statement of Research Problem

One of the major problems concerning textile and leather wastewaters is coloured effluent (Ramakrishna, et al; 1997). This wastewater contains a variety of organic compounds and toxic substances, which are harmful to fish and other aquatic organisms. Dyes even in low concentrations affect the aquatic life and food web. Since many organic dyes are harmful to human beings, the removal of colour from process or waste effluents becomes environmentally important. Due to the large degree of organics present in these molecules and the stability of modern dyes, conventional physicochemical and biological treatment methods are ineffective for their removal (Mckay,1995).

1.3               Justification for the Research

Activated carbon is a widely used adsorbent due to its high adsorption capacity, high surface area, microporous structure, and high degree of surface reactivity, but there are some problems associated with its use,it is expensive and regeneration results in a 10–15% loss of adsorbent and its uptake capacity and therefore this adds to the operational costs. This led to a search for cheaper, easily obtainable materials for the adsorption of dye from industrial effluent (Waranusantigulet al., 2003). As a result, the use of natural waste products and plants has increased considerably during the past years for pollution control applications (Kumar et al., 2009).

Tamarind Kernel is a biological waste material which is readily available and relatively cheap. It can be collected and powdered. (Shanthi and Mahalakshmi,2012).It has excellent potential for the removal of dye from coloured effluent (Patel and Vashi, 2010).TKP has been used to remove dyes from the binary mixture of their aqueous solution (Shanthi and Mahalakshmi,2012).It has also found excellent application in the reduction of Chemical oxygen demand (COD), Total dissolved solids; Sulphates and Turbidity from diary waste water (Shobaet al.,2015).

1.4               Aim and Objectives

The aim of this research is to characterize and utilize Activated Tamarind Kernel Powder (ATKP) in the treatment of Industrial wastewater.

This aim will be achieved by the following objectives:

1. To isolate, carbonize and activate the tamarind kernelpowder

1. To determine some physicochemical parameters which include pH, contact time, adsorbent dose and initial concentration of the ATKP adsorbent
2. To run the FTIR Spectra of the activated ATKP adsorbent before and after treatment with Acid Red 1, Reactive Orange 20 and Reactive Blue 29 (AR1, RO20 and RB29) in order to identify the functional groups responsible for the adsorption of each dye molecule unto the ATKP surface
3. To analyse the effect of Initial concentration, Initial pH, Contact time, Adsorbent dose and operating Temperature in order to determine the optimum conditions for maximum adsorption of the dyes (AR1, RO20 and RB29) from their aqueous solutions
4. To examine the adsorption efficiency of ATKP for AR1, RO20 and RB29 by analysing the adsorption isotherms (Langmuir, Freundlich, Temkin and Dubinin- Radushkevich)
5. To examine the rate of adsorption by studying the adsorption Kinetics (Lagagren Pseudo-First order and Pseudo-Secondorder)
6. To examine the spontaneity of adsorption of AR1, RO20 and RB29 on ATKP through the determination of the thermodynamics parameters (Standard Gibbs free energy, Activation Energy, Enthalpy andEntropy)