Case Studies in Chemical and Environmental Engineering最新文献

Using fungi in decomposition is an important indicator of success in biogas production from oil palm empty fruit bunches (EFB). This study isolated fungi from EFB to be used in the biogas production process. The results identified the fungus as Aspergillus niger based on macroscopic, microscopic, and molecular analysis. Adding the substrate (S) to Palm Oil Mill Effluent (POME) increased CH₄ concentration from 6 % to 60 %. POME-S10 produced 80 % more biogas compared to POME-S0. POME 0-S100 had the highest CH₄ to CO₂ ratio in biogas (±260 %), compared to POME-S0 (±20 %), POME-S4 (±25 %), POME-S7 (±21 %), and POME-S10 (±100 %).

In many developing nations, wood is still commonly used as a fuel for domestic cooking. However, fuelwood combustion can have a pronounced effect on air quality by releasing considerable level of PAHs, thereby posing serious risk to global and environmental health. In this study, seven fuelwood samples were cut into small pieces (100 g) and subjected to open burning with a view to estimate PAHs emissions and their toxicity potentials. During combustion, sixteen basic PAHs were characterized by collecting gaseous emissions from the combustion on PUFs (Polyurethane foams) using probe from the air sampler. The PUFs were washed in a Soxhlet extractor with Acetone to extract the emission which was then analyzed using Gas Chromatography/Mass Spectrometry for characterization. Chrysene and Dibenzo[a, h]anthracene have the highest and lowest PAHs concentrations, respectively. All PAHs levels observed exceeded permissible limits of 1x10⁻⁶ and 1.2x 10⁻⁷ mg/m³ of European Union and World Health Organization, respectively. PAHs from cashew wood showed highest levels of toxicity and mutagenicity, while all the samples have the same carcinogenic effect, indicating that all the samples have the same environmental/harmful impacts, going by ∑PAHcarc/∑PAH ratios (ratio that indicates general harmfulness). The study concluded that despite the relatively low toxic, mutagenic and carcinogenic effects observed in this study, exposure to these concentrations for a long period should be avoided, especially for persons with existing known health conditions such as asthma, lung cancer and cardiovascular diseases.

Zeolites are crystalline microporous aluminosilicate materials used in millions of tons annually in petrochemical and environmental protection industries. Zeolites exist in both natural and synthetic variants, with the former primarily found in abundance in various geological formations, including volcanic and sedimentary rocks. The properties of these natural chabazite such as crystallinity, surface area, and composition can be tailored to enhance their catalytic properties. This work aims to transform low-grade natural chabazite into high-quality catalytic material and examine its activity in the selective catalytic reduction of nitrogen oxides with ammonia reaction. For this purpose, natural chabazite was modified by combining it with a synthetic mixture of silica, alumina, and organic template, followed by hydrothermal crystallization. The initial and modified samples were subjected to various characterization techniques, including XRD, N₂-physisorption, ICP-OES, and SEM, to measure their crystallinity, porosity, elemental composition, and morphology. The characterization results reveal that the modification of natural chabazite enhanced the crystallinity and surface area of the sample, resulting in the incorporation of iron within the micropores of SSZ-13 zeolite. Their catalytic activities were evaluated at varying temperatures, and the resulting Fe/SSZ-13 catalyst showed high activity in the NH₃-SCR reaction.

Nickel-manganese-cobalt (NMC) is a type of cathode material widely used in lithium-ion batteries (LiBs). It performs well on high energy density and thermal stability, but after several charged-discharged cycles, its capacity significantly degrades and becomes waste. Leaching methods with strong inorganic acids are widely used to prevent the release of valuable metals into the environment. Still, these methods must be effectively achieved regarding the low selectivity of specific metals and environmental emissions. This study presents a selective leaching treatment for Ni metals extraction with the organic acid combination of H₃PO₄–H₂C₂O₄ as a leaching agent. The research started with preparation, including discharge, dismantling, calcination steps, leaching, and precipitation. Ni, Mn, and Co leaching efficiency can reach up to 99.90 %, 3.29 %, and 43.65 %, respectively. The leaching experiment shows that a combination system contributes to obtaining excellent selectivity towards Ni metals compared to the others. The optimum conditions for selectively recovering Ni metals were an H₃PO₄–H₂C₂O₄ volume ratio of 8:2 and a liquid-solid ratio of 25 mL/g, leaching at 60 °C for 1.5 h. The thermodynamics and kinetics of the leaching reactions were analyzed to determine the feasibility of leaching three metals. Leachate, which is Ni-saturated from cathode powder, was added with Cyanex272 to facilitate the precipitation of Ni₃(PO₄)₂ with a yield of up to 40 %. This study presents a potential "waste-to-wealth" approach to lead the efficient and environmental recycling of spent NMC cathode LIBs.

This research aims to improve crystal structure and pore size and adjust Brønsted to Lewis (B/L) acid site ratio of spent RFCC catalyst through ultrasound-assisted acid treatment. The catalyst performance was tested to convert palm oil into biofuel through hydrogen-free catalytic cracking. Results showed that crystallinity and pore size of the spent RFCC catalysts were improved. The B/L acid site ratio of the acid treated catalysts could be adjusted, leading to improve the catalysts activity for palm oil cracking process. The main product of the cracking process was liquid fuel product, which was ranged at 85 %–96 % mass fraction. Compared to the liquid fuel product produced by conventional acid treatment, the RFCC catalysts that have been treated using ultrasound-assisted acid treatment produced a higher yield. The GC-MS results showed that hydrocarbons, alcohols, ketones, and aldehydes are main chemical components in gasoline and kerosene.

This study evaluates the effectiveness of Bouznika's (Morocco) urban development plan in mitigating stormwater runoff and pollution. The plan incorporates Low Impact Development (LID) strategies like green roofs, permeable pavements, and rain gardens. Utilizing the Storm Water Management Model (SWMM), the research simulates their impact on runoff volume and pollutant reduction for various scenarios, both individually and combined. The results highlight that combining multiple LIDs achieves substantial pollutant reduction, with green roofs emerging as the most effective single solution. This research seeks to incorporate effective water management techniques by embracing LID practices as part of a sustainable urban development plan.

This study was undertaken to assess the performance of constructed wetland coupled microbial fuel cell (CW-MFC) system to treat real tannery wastewater. Five identically designed CW-MFC systems were setup and operated in a batch mode for two operational cycles. To assess the effect of filling media, CW1-MFC and CW2-MFC were filled with polypropylene granules as an innovative filling media, whereby, CW3-MFC, CW4-MFC, and CW5-MFC were packed with natural gravel. All CW-MFCs were provided with cylindrical graphite anodes, but CW2-MFC, CW4-MFC, and CW5-MFC used irregular-shaped granular graphite underneath the cylindrical anodes as supportive auxiliary anode. Cana indica was utilized as the vegetation model in four CW-MFC systems, but CW5-MFC was maintained unplanted and considered as the control system. The results demonstrated that maximum removal efficiencies of COD were in the range of 98.9%–99.3 %, while, maximum power outputs were recorded as 351.3, 622.3, 538, and 4437 mW/m³ with maximum salinity elimination efficiencies of 62 %, 56 %, 52 %, and 56 % in CW1-MFC, CW2-MFC, WC3-MFC, and WC4-MFC, respectively. Performance of the unplanted CW5-MFC was significantly comparable to the planted CW4-MFC in regard of COD removal and power generation, but with lower efficiency of salinity removal of 16.43 % indicating the plant role in removal of total dissolved solids. Also, the results revealed the absence of arsenic and chromium in the treated effluent. So, besides being an effective approach for the treatment of tannery wastewater, it is a promising, operationally friendly and economically sustainable ecotechnology in the focus of wastewater reclamation and its reuse, as well as energy recovery.

Biodegradable bioplastics provide a promising solution to mitigate environmental harm from petroleum-based plastics. This study focuses on optimizing bioplastic films made from oil palm trunk starch (OPTS), using glycerol (10, 20, and 30 % v/w) as a plasticizer and modified with citric-acid epoxidized palm oil (CEPO). The bioplastics were formed using the solution casting method and analyzed for morphology, functional groups, diffraction peaks, thermal and mechanical properties, degradation time, and compostability. The optimal conditions were achieved with 30 % glycerol (Sample ST-CEPO-GLY30). The addition of glycerol enhances the thermal and mechanical properties, improves the biodegradability, and compostability of the bioplastics.

Microbial fuel cells (MFCs) represent an avenue for harnessing renewable energy from waste substrates; however, their capacity for electrical energy generation remains limited. Therefore, numerous investigations have sought to improve this capability through various modifications, including alterations to the anode, cathode, and chamber configuration. The supplementation of metal ions, such as Cr, Co, and Cu, as micronutrients has emerged as an effective method to improve MFC performance. This study aimed to investigate the effects of Mg²⁺ and Ca²⁺ as eco-friendly micronutrients for accelerating electrogenic bacteria growth and improving the generation of electricity in the MFC. These findings revealed a significant improvement in MFC performance following the addition of these metal ions, attributed to their acceleration of Shewanella oneidensis MR-1 growth. Mg²⁺ succeeds in generating a maximum voltage of 100 mV at 1 and 2 μM Mg²⁺ (3 times higher than Ca²⁺), a current density of 25,000 mA/m² (18 times higher than Ca²⁺), and a power density of 1400 mW/m² (2.5 times higher than Ca²⁺). This finding proves that Mg²⁺ has a positive impact on generating electricity in MFC. Even at minimal concentrations, this study observed increased electric power density.

Bioplastic food packaging is manufactured from natural ingredients with no threat of polluting the environment. There have been no reports using tofu liquid waste as material for making bioplastics using sorbitol concentration treatment. Therefore, this study aimed to determine the effect of sorbitol concentration on the characteristics of bioplastic generated from tofu liquid waste. Before being processed into bioplastic, tofu liquid waste was analyzed for carbohydrates, pH, protein, biological and chemical oxygen demand, as well as total and volatile solids. Data were analyzed with one-way analysis of variance (ANOVA), while sorbitol concentrations used were 0 %, 1 %, 2 %, 4 %, and 8 % with three repetitions. The results of analysis of tofu liquid waste show that this waste can be used as material for making bioplastics. The results showed that the bioplastic produced had thickness values ranging from 0.049 to 0.365 mm, water vapor permeability rates of 0.239–4.644 g m⁻² h⁻¹, tensile strength of 146, 3 to 186.3 kgf. cm⁻², and elongation of 8.52–150.227 %. Variations in sorbitol concentrations had a significant effect on the thickness and elongation values but not on water vapor permeability rate and tensile strength. The best result was obtained with 1 % sorbitol concentration, which produced bioplastic with a thickness value of 0.110 mm, water vapor permeability rate of 0.584 g m⁻² h⁻¹, tensile strength of 146.3 kgf. cm⁻², and elongation of 97, 04 %.