http://103.99.128.19:8080/xmlui/handle/123456789/110 Chemistry 2026-09-13T19:51:16Z http://103.99.128.19:8080/xmlui/handle/123456789/584 VISIBLE- LIGHT DRIVEN PHOTOCATALYTIC DEGRADATION OF ORGANIC POLLUTANTS OVER CuWO4@TiO2 NANOCOMPOSITE: A COMBINED EXPERIMENTAL AND THEORITICAL STUDIES Dutta, Keya Rani; ID:, MSCHEM014F With the growing presence of organic pollutants like methylene blue (MB) in wastewater, there are significant concerns for both the environment and public health, highlighting the urgent need for the development of effective remediation strategies. This study addressed the urgent need for effective remediation strategies for organic pollutants, specifically methylene blue (MB), in wastewater by synthesizing and evaluating a CuWO₄@TiO₂ nanocomposite photocatalyst. A comprehensive characterization using UV-Vis diffuse reflectance spectroscopy (DRS), field emission scanning electron microscopy (FESEM), X ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) surface area analysis, electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV) was conducted to assess the nanocomposite's structural, morphological, and electrochemical properties. Density functional theory (DFT) calculations provided insights into the photocatalytic mechanism, particularly the most stable Ti/Cu@CuWO₄ interface configuration. To enhance predictive modeling for MB degradation, ten machine learning (ML) algorithms, including AdaBoost, Bagging, CatBoost, Decision Tree, Extra Trees, Gradient Boosting, HistGradientBoosting, LightGBM, Random Forest, and XGBoost, were evaluated based on coefficient of determination (R²), mean square error (MSE), root mean square error (RMSE), mean absolute error (MAE), and median absolute error (MedAE). Among this HistGradientBoosting model demonstrating exceptional performance, achieving an R² of 0.9998 in training and 0.9915 in testing, along with low error metrics. Experimental validation under optimal conditions (200 mg/L catalyst, 150 mW/cm² light intensity, 88.6 min reaction time) confirmed a 98.5% MB degradation efficiency, closely aligning with the ML-predicted 98.99%. The nanocomposite exhibited significantly higher catalytic activity as compared to individual CuWO₄ and TiO₂, with rate constants of 0.0302 min⁻¹ for the nanocomposite, 0.0197 min⁻¹ for CuWO₄, and 0.0167 min⁻¹ for TiO₂. Scavenger experiments revealed the order of active species in the degradation process as O₂•⁻ > HO• > ¹O₂ > e⁻ > h⁺, this research emphasizing the combined effectiveness of experimental, computational, and machine learning methods in optimizing photocatalytic water treatment processes. A Master of Science (M.Sc) Thesis in Chemistry Department at Chittagong University of Engineering and Technology (CUET). 2025-04-30T00:00:00Z http://103.99.128.19:8080/xmlui/handle/123456789/582 STUDY ON WASTE WATER TREATMENT PROCESS AND ASSESSMENT OF HEAVY METAL CONCENTRATION IN DIFFERENT TYPES OF ETP AND STP IN SOME INDUSTRIES AT CHATTOGRAM REGION Hassan, Md. Kamrul; ID:, 18MCHEM012P This study delves into a comprehensive assessment of Wastewater Treatment Plants including Effluent Treatment Plants (ETPs) and Sewerage Treatment Plants (STPs) within diverse industries in Chattogram Division, Bangladesh. The investigation was mainly focused on the analysis of ETP samples obtained from the steel and paint industries located in Mirsharai, Sitakunda, Karnaphuli, and Kalurghat industrial areas of Chattogram, as well as STP samples collected from hotels in Cox's Bazar of Chattogram Division. These industries release complex liquid waste rich in dissolved solids, suspended particles, and heavy metal ions. Considering the economic and environmental significance of Chattogram and the detrimental effects of water pollution on ecosystems, the assessment of the discharge of effluents from those industries into water bodies becomes imperative. Thus, this study aims to find out the operational maintenance practices in wastewater treatment plants and to analyze the water quality in ETP samples and STP samples from the industries mentioned above in terms of studying various physio-chemical parameters before and after discharge from the treatment plants. Effluent samples were collected from the ETPs and STPs bi-annually during the dry season (D.S., January- February) and monsoon season (M.S., July- August) using systematic and standardized analytical methods. Sampling procedures involved collecting effluent samples from both the inlet and outlet points of the industrial ETPs and STPs. The water quality was evaluated based on five physio-chemical parameters, namely pH, dissolved oxygen (DO), biological oxygen demand (BOD5), chemical oxygen demand (COD), total dissolved solids (TDS), as well as the concentration of heavy metals including Fe, Cu, Cr, Ni, and Cd. The results were compared to national and international regulations, such as the Bangladesh Standard for Industrial Effluent (BSIE) of Department of Environment (DoE), World Health Organization (WHO) guidelines, European Union Directives (EU-DIR), and US Environmental Protection Agency (US EPA). It was observed that steel-galvanizing industries generate complex wastewater rich in highly dissolved solids and heavy metal ions. Although pH, BOD5, and COD values were within acceptable ranges in these industries, high TDS values were observed. The Fe concentration of discharged stream areas ranged from 0.992 mg/L to 16.89 mg/L, exceeding the guideline limits. Additionally, the Cr concentration in both the inlet and outlet exhibited high concentrations, surpassing the standard limits, particularly those set by the US EPA. Thus, steel-galvanizing industries are likely contributing to water pollution through the discharge of wastewater, particularly in terms of Fe and Cr. In the case of the Paint Industries, after treatment, Fe concentration of discharged stream areas ranged from 2.333 mg/L to 5.117 mg/L exceeded the guideline limits of WHO and BSIE standards and indicated probable water pollution by Fe. Ni in those samples was under the safe limit, and Cd was found under the detectable limit. This study examined the operation of STPs in three Hotel Industries and assessed their impact on water quality in Cox's Bazar, Chattogram Division. Notably, pH levels remained relatively stable, while DO levels fluctuated. The fluctuations of COD levels reflect the presence of various pollutants and similar trends were observed for BOD5. Additionally, TDS indicated the presence of dissolved substances and solid particles. Furthermore, elevated nitrate and phosphate levels raised concerns about nutrient pollution and eutrophication. Fe concentrations remained within regulatory limits, but Cu exceeded limits in specific areas, requiring further investigation. Cr concentrations were within acceptable ranges, while Mn levels significantly exceeded defined limits. Finally, the findings of this study underscore the importance of adopting comprehensive measures and optimizing wastewater treatment processes to address pollution in different industries. A Master of Philosophy (M.Phil.) Thesis in Chemistry Department at Chittagong University of Engineering and Technology (CUET). 2025-02-26T00:00:00Z http://103.99.128.19:8080/xmlui/handle/123456789/546 SIMULTANEOUS REMOVAL OF ANTIBIOTIC AND ANTIBIOTIC RESISTANT BACTERIA BY NANOMATERIAL Maya, Akser Alam Siddiqua The increasing prevalence of antibiotics in water systems poses significant environmental and health concerns, including antibiotic resistance and genotoxicity. This research focuses on synthesizing FeWO4 nanomaterials in three distinct morphologies- nanoparticles, nanorods, and nanofibers via a sustainable hydrothermal process. These nanomaterials were evaluated as heterogeneous catalysts in four different Fenton-based processes: conventional Fenton (CF), photo-Fenton (PF), sono-Fenton (SF), and sono-photo-Fenton (SPF). The performance of each morphology was systematically assessed for the degradation of ciprofloxacin (CIP), a common antibiotic pollutant found in water. The synthesized nanomaterials were characterized using UV-Vis, FESEM, XRD, XPS, EIS, and cyclic voltammetry (CV). The physicochemical analysis also confirmed differences in catalytic performance based on changes in their morphologies. The Response Surface Methodology (RSM) and Central Composite Design (CCD) were used to improve the degradation of CIP by altering three independent variables: solution pH, catalyst dose (mg/L), and reaction time (min). The quadratic model was found to be significant through analysis of variance (ANOVA). This mathematical model fits the experimental data satisfactorily, with R2 = 0.9953 and lack of fit = 0.2441 (P>0.05). Almost complete degradation was achieved at the optimum doses of 100 mg/L of FeWO4, pH = 7, and a 40-minute reaction time. Among the Fenton processes, PF and SPF demonstrated higher antibiotic degradation efficiency than CF and SF processes. Notably, FeWO4 nanoparticles exhibited the best performance, achieving complete degradation of CIP under optimized conditions of pH 7, FeWO4 dosage of 100 mg/L, and a reaction time of 40 minutes, with initial concentrations of 10 mg/L for CIP and 2 mM for hydrogen peroxide (H2O2). FeWO4 nanoparticles were found to be effective for inactivation of ARB E. Coli RP4 by 6.45 log within 20 min. No ARB regrowth occurred after 72 h, which demonstrates the efficacy of this approach in achieving permanent removal of ARB. The synthesized FeWO4 nanoparticles have the potential to degrade demonstrated stability and recyclability, generating potent reactive species such as hydroxyl radicals (HO•), superoxide radicals (O2 •-), and singlet oxygen (1O2). These findings underscore the potential of FeWO4 nanoparticles as effective heterogeneous catalysts in advanced oxidation processes for mitigating antibiotics and antibiotic-resistant bacteria in aquatic environments. A Master of Science (M.Sc) Thesis in Chemistry Department at Chittagong University of Engineering and Technology (CUET). 2024-12-08T00:00:00Z http://103.99.128.19:8080/xmlui/handle/123456789/537 ASSESSMENT OF WATER QUALITY AND PERFORMANCE EVALUATION OF A WATER TREATMENT PLANT: A CASE STUDY Mansur, Abu; ID, 14MCHEM001P Rapid urbanization in Bangladesh places immense stress on the government to provide essential services, with safe drinking water and sanitation being paramount challenges. Population growth and industrialization have intensified the demand for safe drinking water, making water treatment a critical aspect in safeguarding public health and the environment. This study assesses the performance of the Mohara Water Treatment Plant (MWTP) operated by the Chattogram Water Supply and Sewerage Authority (CWASA), which serves as the primary drinking water source for Chattogram City, covering the period from December, 2020 to October, 2021. Performance evaluation of the MWTP focused on the removal efficiency of turbidity and six additional parameters: chloride, ammonia, TSS, COD, Total Coliform, and Fecal Coliform. The results demonstrated commendable performance, with removal efficiencies reaching 99.84 ± 0.03% for turbidity, 60.34 ± 12.51% for chloride, 100% for ammonia, 99.79 ± 0.05% for TSS, 97.11 ± 0.22% for COD, and 100% for both Total Coliform and Fecal Coliform. The study also compares treated water quality to raw water across 26 parameters, aligning with guidelines from the World Health Organization (WHO), Bangladesh Standards and Testing Institution (BSTI), and Environment Conservation Rule-1997 (ECR-97). Notable findings include average Turbidity (0.38 ± 0.07 - 0.64 ± 0.01 NTU), TDS (33.33 ± 1.21 - 767.67 ± 783.25 mg/L), Conductivity (65.5 ± 1.52 – 1323.3 ± 1325.49 µS/cm), pH (6.86 ± 0.02 - 6.97 ± 0.05), Temperature (23.03 ± 0.52 - 27.4 ± 0.09°C) and various other parameters within acceptable limits. Remarkably, heavy metal levels (Arsenic, Lead, Cadmium, Mercury, Chromium) were undetectable, further validating the plant's efficiency in producing safe drinking water. In conclusion, the MWTP consistently demonstrates strong performance, effectively removing impurities and ensuring treated water meets stringent quality standards. This achievement is instrumental in addressing the challenges posed by rapid urbanization in Bangladesh while safeguarding public health and the environment. An M.Phil. thesis from the department of Chemistry, CUET 2023-10-31T00:00:00Z