Case Studies in Chemical and Environmental Engineering最新文献

Cacao husk (CH) is a waste product from Indonesian cacao cultivation and holds potential as an adsorbent. In this study CH was modified using 2-[(methacryloyloxy)ethyl]trimethylammonium chloride (META) for removing nitrate and phosphate ions. The applicability of various adsorption isotherm models (Langmuir, Freundlich, Dubinin-Radushkevich (D-R), and Temkin) was explored, and the chemical structure changes were characterized. The results demonstrate that CH-T-META effectively adsorbs nitrates and phosphates from vinasse waste. The Langmuir isotherm model described the adsorption process excellently, suggesting monolayer adsorption. Fourier-transform infrared spectroscopy (FTIR) analysis revealed the presence of O–H/N–H and CO bonds after vinasse adsorption, indicating potential interaction mechanisms. Additionally, scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses confirmed structural modifications on the CH-T-META surface. Furthermore, CH-T-META exhibited increased H, C, and N content compared to unmodified CH-T-META. Significantly, CH-T-META achieved a removal efficiency (Re) of approximately 93.4 % for nitrates and 96 % for phosphates. These findings strongly support the effectiveness of META modification in enhancing the adsorption capacity of CH for nitrate and phosphate removal from vinasse waste.

Indonesia has the second-highest level of ocean plastic pollution. Polyethylene terephthalate (PET) plastic, used in food and beverage packaging, is the most accessible plastic for recycling. Recycling PET plastic waste can address the issue of waste management and support a circular economy, while protecting the environment. However, consumer participation is crucial for maintaining recycling programs. In this study, we determined the driving forces of customer participation with respect to post-consumption PET waste. The Theory of Planned Behavior (TPB) was used to understand the factors that motivate the consumers’ recycling intentions. We conducted a survey to assess the post-consumption behavior related to PET usage (with 294 respondents), using a questionnaire; to analyze the survey results, we used a structural equation model with partial least squares (SEM-PLS). The attitudes, moral norms, and consequence awareness of the consumers significantly affected their recycling intentions. Perceived behavior and subjective norms did not affect this desire. In Indonesia, consumer behavior after PET consumption primarily involves disposal. This study improves the understanding of consumer behavior and can help businesses and governments to implement strategies that encourage consumers to return used PET goods. In addition, this study enriches the literature on reverse logistics from a consumer perspective.

The electrochemical potential window for nano-sized Niobium carbide (NbC) based electrodes for supercapacitive energy storage applications was investigated. The nano-size NbC electrodes were fabricated and supported on carbon cloth (CC). The NbC@CC materials were assembled into a symmetric supercapacitor with a 1 M sulfuric acid (H₂SO₄) as an electrolyte. The properties of the symmetric supercapacitor were evaluated for their electrochemical behavior, surface properties and morphology. The results showed that the nano-size NbC material was uniformly coated on the surface of CC. The electrochemical performance of the fabricated symmetric supercapacitor was evaluated in the range from -2V to + 2V and showed that the currents were spiked. To further understand the electrochemical behavior, the potentials were systematically reduced to +0.8V and evaluated. The charging-discharging behavior was studied systematically with the aim of avoiding the overestimation of the electrode performance. The specific capacitance was estimated to be around 27 F/g at the reduced potential window. Overall, this work presents a selection of the right potential window for the testing of the NbC based supercapacitor in such a way that avoids the overestimation of the potential window.

This study provides a comprehensive analysis of the ash content resulting from the combustion of heavy fuel oil (HFO) at the Assiut Thermal Power Plant in Egypt, with a specific focus on the enrichment of trace metals and their environmental implications. We meticulously quantified the concentrations of Na, K, Mg, Fe, Ca, and Al in both HFO and the resultant ash. The calculated pollution indices, such as the Single Element Pollution Index (SEPI), Combined Pollution Index (CPI), and Pollution Load Index (PLI), reveal the severe environmental impact. The SEPI values for metals in ash ranged from 384.62 for Al to 34,000 for K, indicating a high contamination level. The CPI was 12,373.4, signifying a severe metal accumulation, while the PLI was 655.1, reflecting a significant pollution load. These findings underscore the urgent need for immediate and effective pollution control measures and sustainable waste management practices. The results provide a foundation for future research on advanced pollution control technologies and the long-term environmental impacts of trace metal accumulation, contributing to the development of improved environmental management strategies.

The widespread use of triclosan (TCS) across the globe poses a substantial threat to both human well-being and the ecosystem. This necessitates the development of eco-friendly adsorption techniques to address triclosan contamination in wastewater. This research aims to develop novel eco-friendly synthesis method using Syzygium jambos (SJ) leaf extract to produce small-sized Mesoporous Silica Nanoparticles (MSNs) by varying surfactant to silica ratio. Different ratios such as 1:50, 1:100, and 1:200 (1 mL of tetraethyl orthosilicate (TEOS) is equivalent to cetyltrimethylammonium bromide (CTAB) in mg) were explored without chemical stabilising agents or alcohol diluents. The synthesized materials were named as MSN1, MSN2, and MSN3. Characterisation studies using Field emission scanning electron microscopy (FE-SEM) showed that MSN3 exhibited smallest size of 30 ± 5nm. The physical, chemical and morphological properties were analysed for the materials using X-Ray diffraction (XRD), Energy-dispersive X-ray spectroscopy (EDS), Zeta potential (ZP), Brunauer-Emmett-Teller (BET), Thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FT-IR). Notably, the developed nanomaterial demonstrated noteworthy stability with a ZP of −33.1 mV and an impressive surface area of 545 m²/g. FT-IR peaks of biosorbent were obtained at 460, 800, and 975 1/cm. This confirms the existence of (Si–O–Si) bonds. The XRD results reveals that it possess amorphous nature of silica without any impurities. N₂ adsorption-desorption studies yielded a pore radius of 16.8 Å and volume of pores are 0.890 cc/g indicating its potential as an adsorbent and its utility for material functionalisation. The developed biosorbent exhibited enhanced adsorption properties for removal of triclosan from synthetic wastewater with 76 % removal at 0.5g/L dose of adsorbent.

Direct contact membrane distillation (DCMD) was applied to the treatment of raw and membrane bioreactor (MBR)-treated municipal landfill leachate. The experiments were conducted using feed side temperatures of 50, 60, and 70^oC while permeate side temperature was controlled at 10^oC. The effects of organic matter, solid particles, and salinity presented in raw leachate and MBR permeate on the DCMD flux and pollutant rejection efficiencies were investigated. Moreover, fouling and wetting of the MD membrane were examined. The experimental results revealed that the application of DCMD to MBR permeate yielded higher fluxes than those of raw leachate but its higher flux decline was also observed due to the formation of denser foulant layer on the MD membrane surface. High organic carbon and salt rejection efficiencies (>90 %) were achieved and maintained in DCMD treating MBR permeate. Significant deterioration of organic rejection efficiencies was observed in DCMD treating raw leachate at higher feed temperature (70^oC) and increasing pollutant concentrations during closed-loop operation. Partial volatilization of volatile fatty acids from the feed side and their penetration through MD was also observed, being more severe at higher feed temperatures. The best condition for the operation of the system was found at 50^oC using MBR permeate as feed water at which pollutant rejection efficiencies were highest while membrane wetting and fouling were also minimized.

Fire suppression and rapid cooling methods are required to reduce the risk of battery fires. However, the liquid and solid residues generated during fire extinguishing pose a risk to the environment and human health. With the aim of correlating the extinguishing efficiency and environmental impact of the residues, fire tests were carried out on NMC lithium-ion pouch cells using different agents, namely water mist, F-500 water additive 2 % (v/v) and CO₂. The combination of cell temperature measurements and videos allowed the efficiency of the extinguishing agents to be assessed. It was found that the efficiency of the water-based agents was higher than that of the gaseous agents (cooling rate of 30.5 ± 4.9 °C/s for water mist, 36.5 ± 6.4 °C/s for F-500 and 20.0 ± 1.4 °C/s for CO₂). Analysis of solid and liquid residues using gas chromatography and induced coupled plasma showed that the use of F-500 resulted in a higher (one order of magnitude) concentration of VOCs in solid residues compared to the other extinguishing agents. The comparison of these concentrations of VOCs with the limits established for waste (EU Regulation N. 1357/2014) showed that the solid residues did not exceed the concentration limit for classification as hazardous waste. Regarding the concentration of metals, the highest values in the solid and liquid residues are due to Li, Ni and Cu. Based on these values, all solid samples can be classified as carcinogenic and toxic for reproduction. While the concentration of metals in the liquid residues was higher than the limit value that poses a risk to aquatic organisms. The overall results showed the need for site remediation and waste management procedures in the event of a major accident.

Metal plating industries generate wastewater containing heavy metals, necessitating effective treatment methods to mitigate environmental contamination. This study investigated the potential of banana peel-derived activated carbon (BPAC) and commercial activated carbon for heavy metal removal, addressing a pressing environmental concern. The analysis encompassed diverse pH levels, crucial for real-world applicability, offering valuable insights into adsorption capacities and kinetics. The results revealed competitive performance of both materials, with typical lead (Pb) removal ranging from 4 to 6 mg/g and cadmium (Cd) from 3 to 5 mg/g. Commercial activated carbon exhibited slightly superior adsorption kinetics and capacities, highlighting its efficacy in heavy metal removal. Throughout the study, optimizing dosage proved essential for maximizing removal efficiency, emphasizing the practical implications of this research. Furthermore, the time-dependent behavior of adsorption kinetics underscored the importance of extended contact times for enhanced removal. Generally, BPAC emerged as a promising solution for heavy metal removal from industrial wastewater. It consistently achieved removal efficiencies typically ranging from 75 % to more than 90 %, making it a viable alternative in the realm of wastewater treatment. At pH 4, BPAC demonstrated significantly higher adsorption capacity, with lead (Pb) at 5.50 ± 0.20 (mg/g) and cadmium (Cd) at 4.10 ± 0.15 (mg/g), compared to slightly lower values for commercial activated carbon, Pb at 5.20 ± 0.25 (mg/g) and Cd at 3.90 ± 0.20 (mg/g). This study contributes significantly to wastewater treatment methodologies, offering sustainable and efficient approaches to address heavy metal contamination in industrial effluents.

The current study successfully reported biosynthesized silver nanoparticles (bio-AgNPs) using an efficient green route, employing Archidendron bubalinum pods extract as reducing and stabilizing agent under sunlight irradiation. A. bubalinum pod extract contains several fatty acid macromolecules, such as palmitic acid, stearic acid, cinnamic acid, and oleic acid. Those compounds contain hydroxyl and carboxyl groups, which play a crucial role in the reduction process of Ag ions to form Ag nanoparticles. UV–Visible spectrophotometry confirmed the formation of bio-AgNPs. The Energy Dispersive X-ray spectroscopy (EDS) and X-ray Diffraction (XRD) also supported the bio-AgNPs formation, consisting of 67.42 % of Ag in a crystalline form. Meanwhile, the materials size was confirmed by Dynamic Light Scattering (DLS), resulting in an average size of 58.9 ± 7.6 nm. This result aligned with Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM), and was confirmed that the material had spherical AgNPs capped with a thin layer. Moreover, this method resulted in stable bio-AgNPs with a surface charge of −32.4 ± 0.35 mV that were stable for over 3 months. Further, the materials were tested against Staphylococcus aureus ATCC6633 and Gram-negative Escherichia coli ATCC6633 bacteria using inhibition test, MIC, and MBC, demonstrating a good inhibition.

This study presents a novel composite nanofiber membrane combining polyacrylonitrile/polyvinylidene fluoride (PAN/PVDF) electrospun nanofibers with locally sourced zeolite from Sumatera, Indonesia, for pollutant dye filtration. The Ze-PAN/PVDF composite nanofiber membrane has 100% methylene blue dye rejection even after five filtration cycles with a permeation flux of 185 L m⁻² h⁻¹ bar⁻¹. The membrane is highly selective, with 100% dye filtration efficiency for cationic dyes (i.e., methylene blue and crystal violet) vs. 78% and 1% for anionic dyes (i.e., Congo red and methyl orange, respectively). For the cationic dyes, the dye filtration mechanism is mainly governed by electrostatic attraction, while the size exclusion mechanism becomes more dominant for the anionic dyes. Overall, these results demonstrate the potential use of Ze-PAN/PVDF composite nanofiber membrane in wastewater treatment applications.