Kinetics of Lead Adsorption by Activated Rice Husk Ash

ABSTRACT 

The need to clean-up heavy metals that contaminate water cannot be over emphasized. This paper examined the kinetics of lead adsorption using activated rice husk ash. The influences of contact time, adsorbent dose, pH and temperature on adsorption were investigated. From the results obtained, by analyzing the effect of contact time, it was discovered that maximum adsorption of about 90 % removal efficiency took 240 minutes using 0.2g of adsorbent. While in testing for the effect of adsorbent dose, the study found that for 180 minutes using a dose of 0.4g of adsorbent, 90 % removal efficiency was obtained at pH 3.0.It was also discovered that the amount of lead ion adsorbed per gram of the adsorbent increased with decreasing concentration of lead (Pb) and that the percentage efficiency of adsorption increased with decreasing temperature. The two theoretical adsorption isotherms, namely, Langmuir and Freundlich were used to describe the experimental results. The Langmuir adsorption isotherm best fittted the model for the study with its correlation coefficient R2 of 0.982. The adsorption of lead (Pb) followed the first order kinetics with the correlation R2 of 0.985 and was found to be pH dependent with a maximum value at pH 3.0. Based on the findings, the study therefore recommended that Industries, governments and individual households should consider the use of rice husk ash in wastewater treatment due to its high efficiency and relative cost effectiveness.

TABLE OF CONTENT

Title Page ………………………………………………………………………………………..ii

Certification Page………………………………………….……………..…………...…..…….iii

Approval Page………………….……………………………………. ……………..………….iv

Dedication ………………………………………………………………………..……….…v

Acknowledgment …………………………………………………………………………….…vi

Abstract…………………………………………………………………………………………vii

Table of Contents………………………………………………………………………....... ….viii

List of Table ………………...…………………………………………………………………xii

List of Plates ………………………………………………………………………..………...xiv

List of Figures ………………………………………………………………………....xiii

CHAPTER ONE:

INTRODUCTION

1.1 Background of Study ……………………………………………… ……………….......1

1.2 Research Problem ………………………………………………………………..……...6

1.4 Research Objective …………………………………………………………….……..6

1.5 Scope and Limitation…………………………………………..………………………...7

CHAPTER TWO

LITERATURE REVIEW

2.1 Adsorption………………………………………………………………………...…….8

2.2 Types of Adsorption

2.2.1 Physical Adsorption……………………………………………………………....9

 2.2.2 Chemisorption………………………………………………………………….......9

2.3 FACTORS AFFECTING ADSORPTION

2.3.1 Particle size of Adsorbent……………...………………………………………...11

2.3.2 Surface Area……………………………………..………………………………11

2.3.3 Temperature…………………….….…………...…………………………...…...12

2.3.4 pH………………………………………………………………………………..13

2.3.5 Solubility of Solute...……………………………………………………………. 14

2.4 Rice Production and Availability of Rice Husk in the world and in west Africa……………………. …………………………………………………………………….14

2.5 Adsorbent…………………………………………….…………………………………. 18

2.6 Adsorption Isotherms

2.6.1 Langmuir Adsorption Isotherm……………………………….…………………22

2.6.2 Freundlich Adsorption Isotherm………..…………………..……………….… 24

2.7. EXISTING KINETICS

2.7.1 Pseudo First Order Kinetics……………………………………………………...25

2.7.2 Pseudo Second Order Kinetics…………………………………………….…….26

CHAPTER THREE

METHODOLOGY

3.1 Collection of Sample……………………………………………………………………..27

3.2 Activation of Rice Husk Ash……….……………………………………………………28

3.3 Preparation of Metal Solution………………………………………………………..….30

3.4 Batch Adsorption of Lead by RHA……….……………………………………………..31

CHAPTER FOUR

DISCUSSION

4.1 Characteristic of Incinerated Rice husk Ash…………….……........................................35

4.2 Effect of Contact Time on the Adsorption rate……………… …………...……………..39

4.3 Effect of pH ……………………………………………………………………………..41

4.4 Effect of Initial Concentration of Lead on the Removal Per % and Adsorption……………………………………………………………………………………..…43

4.5 Effect of Temperature………………………………………………………....................46

4.6 Effect of Adsorbent Dose……………………………………………………. ………….48

4.7 Determination of Suitable Isotherm…………….…………………….………………….49

4.8 Determination of Suitable Kinetics Model……………………..………………………..56

4.9 Coefficient Correlation of Adsorption Isotherms..…………………………………..60-61

CHAPTER FIVE

CONCLUSION AND RECOMMENDATION

5.1 Conclusion……………………………………………………………………………….63

5.2 Recommendation…...……………………………………………………………………63

Reference…………………….…………………………………..……………………..……64 -69

Appendix…………………………………………………………………………………….69-90