http://lib.buet.ac.bd;localhosthttp://:8080/xmlui/handle/123456789/1378 Post graduate dissertations (Theses) of Chemical Engineering (Ch.E) Wed, 15 Apr 2026 19:28:12 GMT 2026-04-15T19:28:12Z http://lib.buet.ac.bd;localhosthttp://:8080/xmlui/handle/123456789/7217 Development of a decision-making framework incorporating safety, environment, and economic criteria for sustainable process design Sultana Razia, Dr. Syeda; Mohaimenol Islam, Md.; 0423022140; 660/MOH/2025 Increasing global legal requirements and rising environmental costs require the chemical industries to minimize their ecological footprint and enhance safety while ensuring economic viability and stability. Conventional sustainability approaches often address these factors separately, leading to suboptimal decision-making in the process design. Currently, there is a growing awareness of simultaneous consideration of all sustainability approaches at the early stage of process design. The present study introduced a unified multi-criteria decision-making (MCDM) framework to identify the most sustainable process routes for the chemical manufacturing process by integrating three key indicators, i.e., safety, environment, and techno-economics. The safety indicator was developed based on chemical hazards as well as equipment safety. Change in Green Degree a measure of greenhouse gas emission was used to determine environmental impact and payback period on the investment was used as economic indicator. The applicability of the proposed framework was demonstrated through a case study of ‘Acetone Production’ by analyzing three acetone production processes with distinct reaction routes, namely, the IPA route, the Cumene Oxidation route, and the Propylene Oxidation route. Each process route was simulated using Aspen HYSYS and the relevant sustainability metrics were computed based on collected data. The MCDM framework was then employed, particularly utilizing The Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) method to evaluate and rank the process alternatives. Acetone production through propylene oxidation emerges as the most sustainable process alternative, with a relative closeness score (RCS) of 0.92, whereas the cumene oxidation route is marked as the least favorable process alternative (RCS 0.01). The IPA dehydrogenation route has a moderate 0.64 RCS. Tue, 25 Feb 2025 00:00:00 GMT http://lib.buet.ac.bd;localhosthttp://:8080/xmlui/handle/123456789/7217 2025-02-25T00:00:00Z http://lib.buet.ac.bd;localhosthttp://:8080/xmlui/handle/123456789/7210 Development of a novel photocatalyst for the degradation of antibiotics in aqueous medium Shahinoor Islam, Dr. Md.; Debanjon Sarker; 0422022049F; 660.2844/DEB/2024 Promising active pharmaceuticals like sulfamethoxazole (SFX), ciprofloxacin (CIP), and metronidazole (MNZ) are bio-persistent and toxic to nature. TiO2 based photocatalysis has been widely utilized in the last few decades to degrade persistent pollutants. Coupling TiO2 with transition metals/metal oxides (Ni, α-Fe2O3) may enhance the efficiency of TiO2. Therefore, this study aims to synthesize single (TiO2, NiO, α-Fe2O3), and composite (α-Fe2O3-TiO2, Ni-TiO2, Ni-α-Fe2O3, Ni-TiO2-α-Fe2O3) photocatalyst to evaluate performance in SFX, MNZ, and CIP degradation with optimization, and kinetics study of superior catalyst. The single and composites catalysts were synthesized by sol-gel, and impregnation method respectively. Characterization was done employing FTIR, SEM, EDS, and XRD. FTIR, validates the presence of respective M-O, and M-O-M bonds α-Fe2O3 (550 cm-1), NiO (435 cm-1), TiO2 (400−800 cm-1). SEM, and EDX show significant modification of the surface morphology, and elemental composition in the composite materials. XRD analysis depicted characteristics peak, and distinct crystallite size of the catalysts. pHpzc analysis shows the synthesized catalysts surface charge between 6.55-7.71. Photodegradation efficiencies were evaluated by degrading MNZ, SFX, and CIP under 21 mW/cm2 UV-254 nm irradiation in a batch reactor. NiO, α-Fe2O3, TiO2, Ni-TiO2, α-Fe2O3-TiO2, α-Fe2O3-Ni, and Ni-TiO2-α-Fe2O3 degrade about 51%, 56%, 59%, 61%, 63%, 64%, and 71% SFX respectively. Accordingly, Ni-TiO2-α-Fe2O3 shows superior photodegradation over CIP (64%), and MNZ (63%). From XRD analysis slightly deviated diffraction peak of both α-Fe2O3 (33.31°), and TiO2 (25.32°) with decreased peak intensity was observed in Ni-TiO2-α-Fe2O3. The average crystallite size decreases from 15.03 nm (TiO2), 45.74 nm (α-Fe2O3), 10.54 nm (NiO), to 9.16 nm in Ni-TiO2-α-Fe2O3. This may lead to the formation of heterojunction and defects in crystal lattice causing decrease of band gap (1.78 eV) and improves of photocatalytic property. Optimization of the reactor performance revealed that Ni-TiO2-α-Fe2O3 performs better at pH 3 for MNZ, and SFX and at pH 9 for CIP. The optimum antibiotic concentration, catalyst dosage, and H2O2 concentration were found to be 10 ppm, 0.25 g/L, and 50 ppm respectively. The kinetic study shows that pseudo-1st order reaction kinetics fits with experimental data. The competitive degradation of SFX, MNZ, and CIP mixture has shown comparatively lower degradation efficiency than single antibiotic. This research establishes Ni-TiO2-α-Fe2O3 composite as a promising photocatalyst for the degradation of persistent pollutant. Sat, 30 Nov 2024 00:00:00 GMT http://lib.buet.ac.bd;localhosthttp://:8080/xmlui/handle/123456789/7210 2024-11-30T00:00:00Z http://lib.buet.ac.bd;localhosthttp://:8080/xmlui/handle/123456789/7208 Life cycle assessment of anaerobic digestate valorization through hydrothermal carbonization Kirtania, Dr. Kawnish; Farhatul Abrar, Md.; 0423022112; 662.88095492/FAR/2025 Anaerobic digestion has been used in rural Bangladesh for several decades to manage livestock and agricultural waste, resulting in biogas production. Despite the benefits associated with biogas generation, the effective management of residual biogenic material or digestate remains challenging. The current practice of handling digestate through open dumping can cause severe environmental issues such as nutrient imbalance and greenhouse gas emissions. Hydrothermal Carbonization (HTC) has emerged as a promising technology for valorizing anaerobic digestate by converting it into valuable products. This study aimed to compare the environmental impacts of anaerobic digestate’s HTC with traditional open dumping from a life cycle perspective. A gate-to-gate life cycle assessment using the ILCD 2011 Midpoint+ method showed that the HTC scenario outperforms open dumping in six of the nine impact categories, specifically reducing acidification, climate change, freshwater ecotoxicity, freshwater eutrophication, human toxicity, and marine eutrophication. For a functional unit (FU) of 1 tonne of anaerobic digestate, HTC reduces acidification and climate change impacts by 78% and 61%, respectively. Additionally, the HTC scenario has 0.4634 kg P eq/FU less impact on freshwater eutrophication than open dumping and reduces freshwater ecotoxicity and particulate matter formation by 93% and 27%, respectively. However, the HTC of anaerobic digestate increases marine eutrophication, photochemical ozone formation, and water resource depletion. Proper post-processing of HTC liquid products and an increase in the energy efficiency of the process can address these issues. Uncertainty analyses via Monte Carlo simulations supported the findings favoring the HTC scenario. Hotspot analysis revealed that the HTC reactor is the main contributor to the most impact categories. Implementing an energy recovery system from the HTC flue gas and utilizing renewable energy sources to meet the energy requirements of the HTC reactor can significantly improve the overall sustainability of the process. Sun, 19 Jan 2025 00:00:00 GMT http://lib.buet.ac.bd;localhosthttp://:8080/xmlui/handle/123456789/7208 2025-01-19T00:00:00Z http://lib.buet.ac.bd;localhosthttp://:8080/xmlui/handle/123456789/7159 Thermosensitive Hydrogels Based on Chitosan and Carboxymethyl Cellulose for Potential Nasal Insulin Delivery System Islam, Nafisa; Shariar, Khondoker Kabbyo; 0422022014; 660.299 /KAB/2024 Managing diabetes, especially for insulin-dependent patients remains a major challenge which often requires multiple subcutaneous injections daily, that can lead to risks like hypoglycemia and lipohypertrophy associated with pain and inconvenience. This study explores a non-invasive alternative insulin delivery system by nasal administration using a thermosensitive hydrogel formulated by chitosan and carboxymethyl cellulose (CMC), with sodium bicarbonate (NaHCO₃) used as initiator. In this study, hydrogels with varying concentrations of chitosan, CMC, and NaHCO₃ were characterized to determine their gelling temperature, mechanical strength, and insulin release profiles. The optimized formulation showed a favorable gelling temperature of 37°C, sufficient mechanical stability for nasal application, a sustained release of insulin over time. Rheological analysis confirmed the thermosensitive behavior, with the hydrogel gelling within 10 minutes at the target temperature. The three optimized hydrogel formulations, Ch/CMC1-NaHCO3 (0.025M), Ch/CMC2-NaHCO3 (0.05M) and Ch/CMC3-NaHCO3 (0.025M) showed gelling temperature of 31°C, 27.5°C and 37°C respectively. (Ch/CMCx denotes that the hydrogel was formlulated using chitosan and CMC at 1:x mass ratio; the number in the bracket denotes the NaHCO3 concentration in M). SEM imaging showed a porous structure favourable to insulin encapsulation and controlled release. FTIR analysis confirmed the integration of chitosan and CMC within the hydrogel matrix, enhancing its biocompatibility and stability. The swelling ratio for the chosen three formulations were between 600% to 800%. The insulin release kinetics showed an initial burst phase, followed by a controlled, slower release, which could allow for more consistent glucose regulation and reduced dosing frequency. Formulations with higher CMC and NaHCO₃ content, Ch/CMC3-NaHCO3 (0.025M) displayed slower release rates, achieving up to 80% insulin release within 5 hours. This release profile matched the Higuchi's model for drug release from an insoluble matrix as a square root of a time-dependent process based on Fickian diffusion. In terms of mechanical properties, increased CMC concentration enhanced the gel’s structural integrity, making it suitable for nasal application, while NaHCO₃ played a vital role in adjusting gelling temperature and pH balance. Considering the cumulative release of insulin, mechanical strength and ease of storage and administration, Ch/CMC3-NaHCO3 (0.025M) would be the best hydrogel for insulin delivery via nasal administration. Sat, 09 Nov 2024 00:00:00 GMT http://lib.buet.ac.bd;localhosthttp://:8080/xmlui/handle/123456789/7159 2024-11-09T00:00:00Z