Razi University

   This research addresses two distinct yet complementary challenges in environmental remediation and fuel upgrading. In the first part, a cerium-based metal-organic framework (Ce-MOF) was successfully synthesized via a solvothermal route and comprehensively characterized. Zeta potential analysis revealed a positive surface charge (+13.1 mV), confirming the suitability of the material for anionic dye adsorption. Nitrogen adsorption-desorption measurements indicated a Brunauer-Emmett-Teller (BET) surface area of 505 m² .g?¹ with a composite Type IVa/II isotherm, demonstrating substantial adsorption capacity. Importantly, the Ce-MOF exhibited a measurable piezoelectric sensitivity of 0.073 mV.N-1, validating its functionality as a piezo-responsive material. The synthesized Ce-MOF was employed as an adsorption-piezocatalyst for the removal of the anionic azo dye Acid Black 172 (AB172) under ambient light conditions, relying solely on atmospheric oxygen and eco-friendly, low-cost flow-induced mechanical energy. Control experiments confirmed that ambient light did not contribute to dye degradation, ensuring that the observed removal originated exclusively from adsorption-piezocatalytic pathways rather than photocatalysis. Scavenger experiments were conducted to elucidate the involvement of reactive oxygen species   (ROS) in the process. Process optimization using Response Surface Methodology (RSM) based on a Central Composite Design (CCD) identified stirring speed, catalyst-to-dye weight ratio, and pH as critical parameters, achieving dye removal efficiencies exceeding 80% at pH = 8, catalyst-to-dye weight ratios above 60, stirring speeds above 600 rpm, and a reaction time of 120 min. Reusability tests and post-cycle structural analyses confirmed the robustness and stability of the Ce-MOF. Kinetic modeling revealed that dye adsorption followed a combined pseudo-first-order (PFO) and pseudo-second-order (PSO) model, indicating the coexistence of parallel adsorption mechanisms. The second part of this dissertation focuses on the development and evaluation of an integrated oxidative-extractive desulfurization process for heavy fuel oil (HFO). The proposed strategy enables precise control of the sulfur content in the final product by adjusting the volumetric fraction of low-sulfur HFO, offering significant flexibility in meeting environmental regulations such as global sulfur emission limits. Considering the substantial economic disparity between high- and low-sulfur HFO, the process demonstrates strong potential for industrial-scale implementation. Catalyst reusability experiments showed that the recovered catalyst, following appropriate pretreatment, could be reused for at least eight consecutive cycles without significant loss of activity, confirming the economic viability of the process. Furthermore, two conceptual process configurations (Multistage Continuous and Mixer-Settler) were designed based on the existing pilot system. Process simulations indicated that these configurations could markedly reduce the consumption of the second-stage catalyst solution, further enhancing the overall economic justification. Compared to conventional hydrodesulfurization (HDS), the proposed process operates under considerably milder conditions, incurs lower costs, and effectively removes low-reactivity sulfur compounds such as benzothiophene (BT) and dibenzothiophene (DBT) from HFO. Beyond sulfur reduction, the process also exhibits the potential to decrease the viscosity of heavy fuel fractions, improving their handling, processability, and applicability to other streams such as vacuum residues.