The general objective of the thesis was investigation of acid treated lemna minor as an adsorbent for removal of Cu (II) and Pb (II) from aqueous solution. Are there sustainable and available bio adsorbents such as lemna minor (duckweed) that can be used for the removal of heavy metals? Can the emerging bio adsorbents actually replace activated carbon which is very expensive adsorbent common today? What is the optimum Operating parameters for biosorption of metal ions under batch studies
Heavy metals are chemical elements with a specific gravity that is at least 5 times the specific gravity of water and are toxic or poisonous even at low concentrations. With increasing generation of heavy metals from industrial activities, many aquatic environments face metal concentrations that exceed water quality criteria designed to protect the environment. They are highly dispersed in a wide variety of economically important minerals. They are released to the environment during mineral extraction process. Therefore, mining activities are the first anthropogenic source of heavy metals.
These heavy metals have potential health risks associated with metal uptake via food chain, dermal absorption or inhaling. High levels of exposure to heavy metals have been proved to cause cancer, organ damage, joint diseases, and in extreme cases, death. Several processes exist for removing dissolved heavy metals, including, ion exchange, precipitation, ultrafiltration, reverse osmosis, electro dialysis and activated carbon. Many of these approaches demand high energy, high cost, advanced operational requirements, result in large amounts of sludge requiring treatment or difficult to treat and be disposed of in an environmentally sound manner, or do not enable recovery of metals or material.
Table of Contents
1. INTRODUCTION
1.1 Problem Statement
1.2 Research Questions
1.3 Objective
1.3.1 General Objective
1.3.2 Specific Objectives
1.4 Significance Of The Study
1.5 Scope Of The Study
2. Literature Review
2.1 Health and Environmental Effects Of Heavy Metals
2.1.1 Health Effects Of Copper
2.1.2 Health Effects Of Lead
2.2 conventional methods
2.3 Bio sorption of heavy metals
2.3.1 Merits Of Biosorption
2.3.2 Biosorbent Materials
2.3.3 Gaps In The Literature
2.4 Characteristics Of Lemna Minor
2.4.1 Previous study of Biosorption on to lemna minor
2.5 Adsorption Mechanism
2.6 Factors Affecting Biosorption
2.7 Adsorption Equilibrium Model
2.7.1 Adsorption Isotherms
2.7.2Adsorption Kinetics Models
3. MATERIALS AND METHODS
3.1 Equipment And Chemicals
3.2 Experimental Methods
3.2.1 Preparation Of Acid Treated Dried Powder Of Lemna Minor
3.3 Characterization Of Lemna Minor
3.3.1 Proximate Analysis Of Lemna Minor
3.3.2. Fourier Transform Infrared Spectroscopy (FTIR) Analysis Of Lemna Minor
3.3.3 X ray Diffraction Spectroscopy Analysis Of Lemna Minor
3.3.4 Point Of Zero Charge
3.3.5 Specific Surface Area
3.4 Preparation Of Aqueous Solution
3.5 Batch Adsorption Experiments
3.5.1 Effect Of pH On Metal Ion Adsorption
3.5.2Effect Of Initial Metal Ion Concentration
3.5.3 Effect Of Adsorbent Dose On Metal Ion Adsorption
3.5.4 Thermodynamics Studies
3.6 Adsorption Isotherms
3.7 Kinetic Studies On Metal Ion Adsorption
3.8 Experimental Design For Biosorption Study Of Copper And Lead
3.9 Desorption Of The Metals
4. Result and Discussion
4.1Proximate Analysis
4.1.1 Point Of Zero Charge
4.2 FTIR Analysis
4.3 XRD Analysis
4.5 Surface Area Analysis
4.6 Effect Of pH
4.7 Effect Of Initial Metal Concentration
4.8 Effect Of Adsorbent Dose
4.9 Temperature Effects
4.10 Adsorption Equilibrium Studies
4.11Thermodynamics Studies
4.12 Kinetic Studies
4.13 Desorption Study
4.14 Data Analysis Using Design Expert 6.0.8
4.14.1Model Adequacy Check
4.14.2 Single And Interaction Effects
4.15 Optimization Of Percentage Removal Of Metal Ions
5. Conclusion And Recommendation
5.1 Conclusion
5.2 Recommendation
Research Objectives and Themes
This thesis investigates the efficacy of acid-treated Lemna minor (duckweed) as a low-cost, sustainable biosorbent for removing toxic heavy metals, specifically copper (II) and lead (II), from aqueous solutions.
- Characterization of the physicochemical properties of acid-treated Lemna minor.
- Evaluation of batch adsorption parameters, including pH, contact time, adsorbent dosage, and initial metal concentration.
- Analysis of adsorption isotherms (Langmuir, Freundlich, Temkin) and kinetic models to determine the adsorption mechanism.
- Optimization of the biosorption process using Central Composite Design (CCD) via Design-Expert software.
- Assessment of the desorption and regeneration potential of the spent biosorbent for metal recovery.
Excerpt from the Book
2.5 Adsorption Mechanism
The cell wall is the first component that comes into contact with metal ions, where the solutes can be deposited on the surface or within the cell wall structure. The solute uptake by live/dead cells is extracellular, the chemical functional groups of the cell wall play vital roles in bio sorption. Due to the nature of the cellular components, several functional groups are present on the bacterial cell wall, including carboxyl, phosphonate, amine and hydroxyl groups (Van der Wal et al, 1997).
Biomass possess an abundance of functional groups that can passively adsorb metal ions. The term adsorption can be used as a general term and includes several passive, i.e. non-metabolic, mechanisms such as: complexation; chelation; co-ordination; ion exchange; precipitation; reduction. For adsorption to occur, there must be forces that attract the adsorbate to the solid surface in a solution. This mechanism or forces which attract the adsorbate to the solution of the solid interface can either be physical or chemical (Mckay, G. 1996).
Summary of Chapters
1. INTRODUCTION: Provides the background on water pollution caused by heavy metals, defines the problem, and outlines the research objectives for using Lemna minor as a biosorbent.
2. Literature Review: Surveys existing research on heavy metal toxicity, conventional treatment technologies, and the scientific principles behind biosorption and Lemna minor characteristics.
3. MATERIALS AND METHODS: Details the experimental procedures for preparation, activation, and characterization of the biosorbent, as well as the experimental setup for batch adsorption and desorption tests.
4. Result and Discussion: Analyzes the experimental data, including surface characterization, isotherm and kinetic model fitting, and statistical analysis via ANOVA for copper and lead removal efficiency.
5. Conclusion And Recommendation: Summarizes the key findings, confirming the suitability of Lemna minor for heavy metal removal, and proposes directions for future research applications.
Keywords
Heavy metals, Lemna minor, Biosorption, Desorption, Percent removal, Adsorption capacity, Copper (II), Lead (II), Acid treatment, Wastewater treatment, Adsorption isotherms, Kinetic modeling, Design-Expert, Sustainability, Biomass.
Frequently Asked Questions
What is the primary objective of this research?
The primary objective is to evaluate the capacity of acid-treated Lemna minor as a sustainable and cost-effective biosorbent for the removal of copper (II) and lead (II) from aqueous solutions.
Which heavy metals are focused on in this study?
The study specifically focuses on the removal of copper (II) and lead (II) due to their toxicity and presence in industrial effluents.
What scientific methods are used to analyze the adsorption data?
The research employs various adsorption isotherm models, including Langmuir, Freundlich, and Temkin, alongside kinetic models such as pseudo-first-order, pseudo-second-order, and intraparticle diffusion.
What is the significance of using Lemna minor?
Lemna minor (duckweed) is chosen because it is an abundant, fast-growing, renewable, and cost-effective aquatic plant, offering a greener alternative to expensive materials like activated carbon.
How was the adsorption process optimized?
Optimization was conducted using Design-Expert 6.0.8 software, applying Central Composite Design (CCD) to investigate the interactions between pH, initial metal concentration, and adsorbent dosage.
What are the main findings regarding the adsorption mechanism?
The results indicate that the adsorption process follows a chemisorption mechanism, where functional groups like hydroxyl, alcohol, alkene, and carboxyl groups on the Lemna minor surface play a critical role in metal binding.
What was the observed effect of pH on the removal efficiency?
The study found that the removal efficiency for both metals is strongly pH-dependent, with optimum removal occurring at pH 11 for lead and pH 9 for copper.
Can the biosorbent be regenerated after use?
Yes, the study includes a desorption study using 0.1M HCl, demonstrating that the metals can be recovered and the adsorbent has potential for regeneration.
- Citar trabajo
- Yalembrhan Debebe (Autor), 2018, Acid-treated dried lemna minor as an adsorbent for the removal of copper and lead from an aqueous solution, Múnich, GRIN Verlag, https://www.grin.com/document/430754
