Case Studies in Chemical and Environmental Engineering最新文献

This study aims to determine the performance of a commercial corrosion inhibitor (mixture of ethanediol, 2-butoxy ethanol, and fatty acid amine) in inhibiting weldment corrosion. The inhibitor's effect on parent metals (PM), heat affected zone (HAZ), and weld metal (WM) has been investigated on the corrosion behaviour of X65-welded structures in brine solution (10 m/s) using submerged jet impingement (SJI) flow loops. The results show that inhibitors can reduce the corrosion rate by 10 times to 0.36 mm/y for WM. Linear polarization resistance and electrochemical impedance spectroscopy (EIS) show that the WM exhibited the highest corrosion rate.

Bone is the second organ of the human body that has the most transplants. The concept of bone repair has evolved over the past five decades and is known as the third generation of biomaterials. During the integration of nanotechnology with bioceramics, an emerging research field called nanobioceramics has been born within the third generation of biomaterials. Due to the chemical similarity with the mineral content of human bone, nanobioceramics are included in the definition of a new generation of biomaterials whose main purpose is to create a microenvironment to improve cellular responses leading to osteogenesis. Hydroxyapatite is a member of the calcium phosphate family. This substance, which is a bioactive and biocompatible compound, is considered the main mineral component of bone tissue. Due to the chemical and structural similarity of this compound with bone, it is widely used in the field of bone tissue repair and dental and orthopedic applications. Many of the basic properties of hydroxyapatite can be improved and improved by changing the scale of its particles to nanoparticles. Therefore, in recent years, various methods for the synthesis of nanohydroxyapatite have been reported. Using different characterization methods, the quality of synthesized nanostructures can be checked. In addition to bone-related fields, nanohydroxyapatite is also used as a carrier in the transfer of various materials, including drugs, vitamins, and proteins. In this article, in modern times, advances in the field of biomedical research focusing on the use of bioceramics in the treatment of various diseases, the function of vital organs, and tissue engineering have brought new hopes to regenerative medicine. Various methods are being investigated to synthesize bioceramic materials using natural and synthetic materials. There are several challenges to enable cost-effective material synthesis and minimize the rejection of bioceramics in biological systems. One of the major challenges in incorporating foreign materials into body systems is to improve their acceptance and reduce their rejection by humans and other organisms by studying their immune responses. When developing biocompatible ceramic materials, the mechanical and chemical properties of the ceramic material are one of the most important parameters for their acceptance in humans. The evaluation criteria of mechanical, chemical and biological properties of bioceramics using various existing approaches play a crucial role in validating the use of bioceramics. State-of-the-art techniques for synthesis and evaluation of bioceramic properties can improve their biomedical applications.

Recently, microbial-induced carbonate precipitation (MICP), plays an important role in biogeotechnical engineering applications and is an environmentally friendly bioremediation technique. MICP includes the bioprecipitation of calcium carbonate from media using bacteria and fungi. In this work, the possibility of employing waste products, for instance, eggshells and scallop shells, as alternative-sustainable calcium sources. For MICP to be successful, high urease-producing bacteria had to be locally isolated and selected. Significant urease activity was detected in eight isolates. One isolate identified Bacillus licheniformis which has the greatest urease activity at 13.2 mM urea/min and maximum bioprecipitation activity, was selected. The ability of various calcium sources, to induce carbonate precipitation was tested. A ratio of 1:1 calcium source to urea had the highest carbonate precipitation among these sources. A 1 optical density of cell bacteria produced the maximum carbonate production of 1.7 and 1.4 gm for scallop shells, and eggshells respectively, according to an assessment of the effects of different bacterial concentrations which plays a crucial role in enabling MICP. The optimal pH range for precipitation is between 7 and 8.5 for urea hydrolysis. The precipitates contained calcite crystals with a predilection for crystal morphology, according to XRD, EDS-EDX, and FE-SEM. The potential of using waste products as calcium sources in biogeotechnical engineering is significant, as waste products offer a sustainable and environmentally friendly method for improving the durability of applications such as building and cleanup projects.

Mercury, emitted from various industries, is toxic and has devastating environmental consequences. Therefore, it becomes imperative to monitor the levels of mercury closely. This work mainly focuses on preparing inexpensive zeolite-coated kaolin membranes for separating Hg²⁺ from water. The membrane support was prepared using kaolin (50 wt%), quartz (25 wt%), and calcium carbonate (25 wt%). This mixture was blended with a 3 % hydroxypropyl methylcellulose (HPMC) solution and then passed through an extruder to obtain tubular support, which was further sintered at 950 °C. The zeolite-coated membrane (ZP membrane) was fabricated by subjecting the sintered support to a 48-h hydrothermal synthesis in 7 Na₂O: 1 Al₂O₃: 10 SiO₂: 205H₂O gel at 90 °C. The isoelectric point of the ZP membrane was estimated to be 4.5. The zeolite-coated membrane displayed a pure-water permeability of 22.7 × 10⁻⁹ m³/m² s kPa, a porosity of 31.72 ± 0.86 %, and a pore size of 90 nm. The performance of the ZP membrane in separating the Hg²⁺ ion from an aqueous solution was investigated by pressure variations (69–345 kPa) and feed concentration (0.5–10 ppm). The results clearly showed that in all cases, the zeolite-P membrane exhibited more than 99 % rejection of Hg²⁺ ions from aqueous solutions during the filtration experiments. Thus, the prepared ZP membrane can effectively be used for the separation of Hg²⁺ ions from wastewater.

Improper management of agro-industrial food waste represents a significant issue due to the associated uncontrolled release of climate-altering gases, total volatile organic compounds (TVOCs) and odours. The present study proposes an innovative solution to mitigate these emissions with supercritical carbon dioxide impregnation, employed to load R-Carvone into patches made from compostable pouches directly applied on two matrices: pork fat and tomato peel and seeds. Under optimized operating conditions (33 °C, 200 bar, 2 bar min-1) patches with 54 % R-Cav were produced, resulting in reduced CO2 and TVOCs emissions up to 200 and 0.2 ppm per gram, and reduced associated odour annoyance.

This work focuses on the interplay between redox couple activity and electrolyte concentration in terms of quantum cell efficiency and photocurrent in CdS thin-film photoelectrochemical solar cells. Optimization of the CdS thin-film electrodes was achieved through electrodeposition and chemical bath deposition, followed by controlled annealing. UV–visible electronic spectroscopy and Tauc measurements were used to determine that the energy gap of the CdS electrode was 2.4 eV. XRD confirmed the cubic structure of CdS, while SEM images revealed the agglomeration of CdS nanoparticles. The PEC performance with respect to different concentrations of NaOH/Na₂S/S electrolyte, that is, 0.25, 0.5, 0.75, and 1 M, was studied; the results revealed that the activity of the redox couple improved the efficiency. In this context, the ionic strength and redox solution activity were calculated by the Debye–Hückel equation. Specifically, a clear correlation was clearly obtained in this study between the PEC efficiency and solution activity (R² = 0.95 for the quantum cell efficiency and R² = 0.93 for the photocurrent density), which is greater than that obtained for the concentration alone, for which R² = 0.88 for the quantum cell efficiency and 0.83 for the photocurrent density. Consequently, the variation in ionic activity is one of the major parameters controlling the performance of PECs and, accordingly, solar energy conversion.