ABSTRACT

Activated tamarind kernel powderwas 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, and free energy which were determined using the Van‘t Hoff equations were found to

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INTRODUCTION

1.1       Background of Study

Environmental pollution control is said to be amatter 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