Case Studies in Chemical and Environmental Engineering最新文献

The extracted ash from common water reeds locally available in Iraq was used as a cost-effective silica source for single-step synthesis of a heterojunction photocatalyst (Ag₂O@CRA) combining 9.75 % Ag₂O and a surface area of 99.849 m²/g. The Ag₂O@CRA photocatalyst was used to investigate methylene blue (MB) degradation which was eliminated at an initial MB concentration of 20 mg/L, Ag₂O@CRA dose of 0.1g/100 mL, pH of 7 after 60 min at visible light. This photocatalyst displayed excellent stability after five cycles with more than 91 % removal of MB dye. The ^⦁OH was the main radical involved in the MB degradation.

The paper evaluates the EW-1000 Atmospheric Water Generation-Vapor Compression Refrigeration system (AWG-VCRS) as a sustainable alternative to seawater desalination in the GCC. Conducted in Masdar City, Abu Dhabi, from July 2023 to January 2024, the study measured temperature, humidity, energy consumption, and water production. Key findings include a peak water production of 1500 LPD in September and an average Specific Energy Consumption (SEC) of 0.26 kWh/L. Productivity decreased by 71 % in cooler, dryer months. With a coefficient of performance (COP) of 3.6, the system aligns with conventional air conditioners, highlighting its potential for enhancing water security in arid regions.

Water parks often use chlorine for water disinfection despite its ineffectiveness and health risks. This research explored the efficacy of combining electromagnetic treatment (EMT) with chlorination in disinfecting swimming pool water. Water samples, with different organic loads, were subjected to EMT-chlorination tests. EMT significantly affected the physicochemical parameters of the water, notably reducing turbidity by 50 % and decreasing COD levels compared to systems without EMT. The system with EMT reported lower chlorine consumption, suggesting a lower formation of chlorogenic by-products. Therefore, it is evident that the combined method can decrease the levels of organic contamination in the water, reduce the presence of algae, and minimize the consumption of conventional chemical disinfectants, thus reflecting an interesting synergy between EMT and chlorination, which could be advantageous from a health, environmental and economic perspective.

In this study, fabrication of mesoporous nanocellulose-hectorite-alginate bead (B-NcH) composites and their application for adsorption of MB from water was carried out. The synthesis of nanocellulose (NC) was conducted from mangosteen waste peel (Garcinia mangostana L.). Garcinia mangostana L. peel had 58.9 ± 0,41 % content of cellulose. NCs was successfully isolated using the acid hydrolysis method. NC from Garcinia mangostana L. peel had a diameter of 24.5 ± 0.2 nm and a length of 381.2 ± 10.4 nm. The superabsorbent was composed of nanocrystalline cellulose, mesoporous hectorite, and alginate. The functional group, phase, and morphology of composite was investigated. The composite with 5 % NC had excellent mechanical strength. The B-NcH5 showed a high adsorption capacity of methylene blue (MB), reaching 98.64 % at an adsorbent dose of 30 mg for 90 min. The presence of hectorite can increase the adsorption ability compared to NCs-alginate. The equilibrium adsorption data followed the Freundlich isotherm; however, the kinetics of adsorption showed the usefulness of adopting the PSO kinetic model. The highest adsorption capacity of B-NcH5 for MB was determined to be 57.59 mg/g. For thermodynamic studies, it was revealed that the adsorption of MB on BNcH-5 is a spontaneous and endothermic process. The removal efficiency was observed in six consecutive cycles, indicating at the favorable reusability of this adsorbent. These results validate the potential use of this B-NcH5 adsorbent for water treatment applications.

The utilization of catalysts in organic reactions represents a widely utilized principle within the concept of green chemistry. This study focuses on utilizing hydroxyapatite from green mussel shell waste combined with CoFe₂O₄ as a heterogeneous catalyst for synthesizing 2-amino-4H-chromene derivative. The green mussel shells were calcined to produce CaO, which was then utilized as a precursor in the synthesis of hydroxyapatite, and then combined with cobalt ferrite through the coprecipitation method. Diffractogram analysis confirmed successful formation of hydroxyapatite, CoFe₂O₄, and their composite, validated against JCPDS data. Morphological analysis revealed irregular shapes, while magnetic property analysis indicated a slight decrease in the hydroxyapatite-CoFe₂O₄ composite compared to pristine CoFe₂O₄. Catalytic activity assessment demonstrated high yields (up to 88 %) under optimized conditions: catalyst concentration of 7.5 % w/w, reaction time of 15 minutes, in ethanol solvent, and using 300 Watts microwave power. The reusability of hydroxyapatite-CoFe₂O₄ as a catalyst, supported by the XRD and FTIR analyses, demonstrates its structural and chemical stability after five catalytic cycles, showcasing its potential as an eco-friendly and efficient catalyst.

In this paper, we propose a new mechanical process (opener machine) mostly adaptive to recycle waste yarn fibers. We study the effect of the process design and the number of passages on the overall fiber quality and process yield for colored denim yarn waste. Results show that the process design has a more significant effect on the overall fiber quality than the number of passages. Better results were obtained for the process yield, fiber length, fiber strength, and fiber quality index with an opener with seven rollers OP2 compared to an opener with two rollers OP1. No significant effect was found on fiber fineness.

Using an OP2 machine instead of OP1 increased: the yield by more than 150 %, mechanical properties by 5 %, Uniformity Index by 10 %, fiber mean length by 3 % and Fiber Quality Index by 9 %. It also decreases Short Fiber Count by 35 %

When the number of passages is four (instead of one), the yield increased by about 55 %. the fiber mean length increased by 4 %, the Short Fiber Count decreased by 12 % and the Uniformity Index decreased by 4 %.

In conclusion, the best combination for our study was obtained using the OP2 machine and four passages. This combination achieved a yield of more than 75 %, Neps = 189 Cnt/g; ML(w) = 19.6 mm; SFC = 20.6 %, UI = 63.8 %, Fineness = 146 mTex; Str = 26.3 (cN/tex)

The hypothesis that mechanical process design and the number of passages in the process have an important effect on fiber quality and the process yield for colored denim yarn waste was justified.

The thermo-osmotic energy conversion (TOEC) process harnesses low-grade waste heat for electricity generation. Key to TOEC is selecting membrane materials, with polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE) being common choices. This study provides the first life cycle assessment (LCA) of PTFE and PVDF membranes, assessing both lab-scale and large-scale production. It identifies key chemical contributors to their environmental impact and cumulative energy demand (CED). PTFE has a lower CED in regions with renewable energy, while PVDF may be viable in areas reliant on non-renewable biomass. These insights can inform decision-makers in strategizing the implementation of TOEC processes for sustainable development.

Photocatalysis has attracted attention, utilizing solar energy directly to catalyze chemical reactions. This research synthesized Fe₂TiO₅/Ag/C nanocomposites as photocatalyst material using a wet milling process and confirmed with comprehensive characterizations. Impregnation Ag/C produced crystal defects Fe₂TiO₅, resulting smoother amorphous surface with increased surface area and higher volume and size of pores. The optical properties of Fe₂TiO₅/Ag/C absorb light at 600 nm with a band gap of 2.04 eV and thus can be classified as semiconductor materials sensitivity in visible light. Finally, the Schottky barrier and surface plasmon resonance effect of Ag/C was proposed to describe the mechanism of the photocatalytic process on the Fe₂TiO₅/Ag/C.

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.