الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 159 |  |  |
| | | from | 159 | | |
Abstract
Chapter 1: Introduction
This chapter underscores the critical need for effective wastewater treatment due to increasing
water scarcity and pollution. It highlights advancements in wastewater treatment technologies,
focusing on advanced adsorbents like Metal-Organic Frameworks (MOFs) and Graphene Oxide
(GO). These materials exhibit high efficiency in removing pollutants, including heavy metals,
owing to their unique structural properties. Additionally, chitosan, a natural polymer with
exceptional adsorption capabilities, is introduced, especially in composites with MOFs and GO,
enhancing their adsorption performance.
Chapter 2: Experimental Section
This chapter describes the materials and methods employed in the research. It includes the
synthesis processes for the CPBr-MIL-88A@AmGO composite and ZIF-8/EDA-GO@Chit beads.
Characterization techniques such as Fourier Transform Infrared Spectroscopy (FTIR), X-Ray
Diffraction (XRD), Scanning Electron Microscopy (SEM), Zeta Potential Analysis, and X-Ray
Photoelectron Spectroscopy (XPS) are discussed to analyze the properties of the adsorbents. The
chapter also details batch experiments performed to evaluate the adsorption performance of the
adsorbents under different conditions, including pH, dosage, initial concentration, temperature,
and reusability.
Chapter 3: Results and Discussions
Adsorption Capacity and Efficiency Both CPBr-MIL-88A@AmGO composite and ZIF-
8/EDA-GO@Chit beads demonstrated high efficiency in removing Cr(VI) from aqueous solutions.
v
The CPBr-MIL-88A@AmGO composite achieved a maximum adsorption capacity of 306.75
mg/g at pH 2, while the ZIF-8/EDA-GO@Chit beads reached 243.90 mg/g, indicating their
effectiveness in capturing Cr(VI) ions. Influence of pH Optimal adsorption occurred at lower pH
values due to the positive charge on the adsorbents attracting negatively charged Cr(VI) ions. As
pH increased, adsorption efficiency decreased, highlighting the importance of pH control for
maximum efficiency. Effect of Initial Cr(VI) Concentration and Dosage Increasing the initial
concentration of Cr(VI) led to higher adsorption capacity up to a saturation point. Similarly,
increasing the adsorbent dosage improved removal efficiency to an optimal level, beyond which
further increases had little effect. Kinetic Studies The adsorption kinetics followed the pseudosecond-order model, indicating chemisorption as the rate-limiting step. This suggests that chemical
interactions control the adsorption process. Isotherm Studies The adsorption isotherms fit better
with the Langmuir model, indicating monolayer adsorption on a homogeneous surface. The
Freundlich model was also applicable but to a lesser extent, confirming that adsorption primarily
occurs on uniform sites. Thermodynamic Studies Thermodynamic parameters showed the
adsorption process to be spontaneous (negative ΔG°) and endothermic (positive ΔH°), with
increased randomness at the solid-solution interface (positive ΔS°). These parameters highlight the
feasibility of the adsorption process. Impact of Interfering Ions Common anions (chloride, nitrate,
sulfate) and cations (sodium, calcium, potassium) affected Cr(VI) adsorption efficiency. Chloride
and nitrate had minimal impact, while sulfate significantly reduced efficiency by competing for
active sites. Calcium ions exhibited substantial interference due to stronger competition.
Reusability Both adsorbents demonstrated high reusability, maintaining significant efficiency over
multiple cycles. The CPBr-MIL-88A@AmGO composite retained over 82% efficiency after seven cycles, and the ZIF-8/EDA-GO@Chit beads showed 69.26% efficiency after ten cycles, indicating
their sustainability for long-term wastewater treatment.