Canadian Journal of Chemical Engineering最新文献

Lignocellulosic mass consists of cellulose, hemicelluloses, and lignin. Although biomass promises to be efficiently used for biofuel production and many other value-added products, lignin present in lignocellulosic biomass affects the hydrolysis of cellulose and hemicelluloses, making it necessary to develop techniques that provide better lignin removal efficiency and high cellulose hydrolysability. The current work aims to maximize lignin removal in sawdust and develop an understanding of the hydrolysis of pretreated biomass for sugar production. Different parameters such as solvent to solid ratio, temperature, and reaction time have been considered based on the design of experiment to understand the effect on the delignification and saccharification processes. After treating sawdust for 1.5 h, it was observed that a maximum of 85% lignin was removed at a temperature of 131°C and solid loading of 16 g. Subsequent hydrolysis of delignified sawdust at 131°C temperature, solvent to solid ratio 15, and 0.5 h resulted in a maximum reducing sugar production of 26.82 mg/mL. The study elucidated the optimum conditions for the effective processing of sawdust in terms of delignification and saccharification, leading to maximum benefits in lignin removal and sugar production.

The use of mixed suspension mixed product removal (MSMPR) system in the pharmaceutical industry to produce active pharmaceutical ingredients is well known. In industrial settings, the MSMPR system is subject to lot of process uncertainty which, if ignored, might result in poor product quality. In this work, the process uncertainty involved in MSMPR is targeted during the process optimization stage to find robust optimal operating conditions. The temperature and the residence time inside each cascaded MSMPR unit, altogether six, are considered as uncertain parameters. A sampled set of uncertain data points for such six different uncertain parameters are clustered using a novel support vector clustering (SVC) based algorithm. The uniqueness of this algorithm lies in its ability to fine-tune the hyper-parameters of SVC while intelligently clustering the uncertain data points into optimal number of clusters. Such identified clusters are helpful to generate more samples from the intended regions rather than generating them randomly to avoid proposing conservative solutions. Both best-case and worst-case scenarios for robust oOptimization (RO) are considered with $��500�,�1000�$, and $��1500�$ samples. As the model has to be evaluated for a large number of samples and the MSMPR models are time-consuming to evaluate, a surrogate model of the MSMPR process is developed to perform optimization under uncertainty. Performance metrics are used to quantitatively establish the superiority of the SVC based RO over the box-sampling based RO.

The Bayer process is a cornerstone of alumina production, and its precipitation stage holds the key to both efficiency and product quality. In this study, we embarked on a comprehensive exploration of strategies to enhance the precipitation extent of aluminium hydroxide, a pivotal step in the Bayer process. Utilizing a newly constructed reactor, along with experiments using reactors in series, we rigorously experimented with various factors, including the addition of hydrogen peroxide (H₂O₂) as an enhancer, seed activation methods, the integration of a hydrocyclone within the processing unit, the application of a magnetic field, and the injection of supersaturated liquor midway through the process. These diverse strategies were systematically assessed to decipher their individual and synergistic effects on precipitation extent. Our research aims to uncover the optimal conditions for maximizing alumina precipitation while maintaining product quality and seed particle stability. By offering new insights and practical solutions, this study contributes to the ongoing advancement of alumina production within the Bayer process.

In order to solve the problems of poor temperature resistance and low crosslinking efficiency of crosslinking agent for sulphonated guar gum fracturing fluid, in this paper, nano-silica was reacted with 3-aminopropyltriethoxysilane to obtain surface-modified nano-silica, which was then reacted with boric acid and n-butyl titanate to obtain nano-silica-based boron-titanium composite crosslinking agent. Its physical properties and structure were characterized by infrared (IR), laser particle size analysis, X-ray diffraction (XRD), and atomic force microscopy (AFM). The sulphonated hydroxypropyl guar gum fracturing fluids formed by nano-crosslinking agent were analyzed: When the temperature was uniformly increased from 25 to 120°C and the shear rate was 170 s⁻¹, the viscosity was finally constant at about 50 mPa · s, which indicated that the temperature and shear resistance were good; the system had a better filtration-loss reduction performance; the average sedimentation rate of ceramic grains in the fracturing fluid system was 0.00872 cm · min⁻¹, indicating that the system had good sand carrying performance; the damage rate of fracturing fluid filtrate to the core was 23.33%; the gel breaking performance test showed that the fracturing fluid had good gel breaking performance. By analyzing the performance of the fracturing fluid, it can be seen that the nano-crosslinking agent has the advantages of good temperature resistance and high cross-linking efficiency compared with the traditional boron and titanium cross-linking agents.

Organic electroactive materials, particularly semiconducting polymers, are at the forefront of emerging organic electronics. Among the plethora of unique features, the possibility to formulate inks out of these materials is particularly promising for the large-scale manufacturing of electronics at lower cost on a variety of soft substrates. While solution deposition of semiconducting materials is promising for developing printed electronics, the environmental footprint of the materials and related devices needs to be considered to achieve sustainable manufacturing. Towards the development of greener printed electronics, this work investigates the utilization of a non-toxic, environmentally-friendly solvent, namely branched polyethylene (BPE), to formulate semiconducting inks. Focusing on a diketopyrrolopyrrole-based (DPP) semiconducting polymer, shellac as dielectric, and BPE as the solvent, solutions were prepared in different concentrations and their rheological properties were characterized. Then, printing on polyethylene terephthalate (PET) substrates using two different techniques was performed to fabricate organic field-effect transistors (OFETs). Both printing techniques yielded OFETs with good performance and device characteristics, averaging approximately 10⁻² and 10⁻⁴ cm² V⁻¹ s⁻¹, respectively, for slot-die coating and direct-ink writing deposition. Notably, despite some difference in threshold voltages, OFETs produced via slot-die coating and direct-ink writing showed comparable charge mobilities to previously reported OFETs prepared from similar materials, particularly those prepared on silicon dioxide wafers. Overall, this work confirms the suitability of BPE to formulate semiconducting inks to develop printed electronics in a greener manner. The printing methodology developed in this work also open new avenues for the design of functional printed electronics and related technologies.

Fugitive emissions from petrochemical facilities have become a major concern due to their impact on plant productivity, the environment, and health. In regard to health, petrochemical workers are at higher occupational health (OH) risk due to their continuous exposure to these harmful emissions. Inherent OH and safety indexes are the most common methods used for assessing OH risk due to fugitive emissions. These methods usually focus on the sources of health hazards, such as chemical substances, process conditions, and process equipment. Therefore, these methods are considered good for measuring the severity of the OH risk. However, based on the source, pathway, receptor (SPR) model, the OH risk due to fugitive emissions is also dependent on the pathway and receptor, where leak and exposure hazards may take place, respectively. For a holistic OH risk assessment, these hazards need to be considered. This was achieved by developing an OH risk assessment methodology that provides an effective assessment that takes into consideration hazards at the source, pathway, and receptor. This paper focuses on the source part of the SPR model, while the pathway and receptor parts will be covered in future publications. This paper presents an index-based method named the inherent health hazard level index (IHHLI) developed for evaluating the severity of the fugitive emission-induced OH risk. The IHHLI is developed by an expert-based selection of the most common and relevant health hazard indicators published in the literature. Based on industry testing, the IHHLI can provide a reliable OH hazard evaluation.

Enhancement of a sustainable environment through the choice of a selective catalyst with high activity, regeneration nature, and high stability is an important aspect to be focused on to achieve a high yield and maximum conversion of feedstock to biodiesel (1st generation biofuel), and also in the biomass valorization/pyrolysis (2nd generation biofuel synthesis). Depending on the nature of the catalyst and synthesis method adopted for biofuel production and biomass valorization, the variations in the process conditions, final yield, and conversion are varied accordingly. A prospective development and application of perovskite catalysts in the synthesis of 1st and 2nd generation biofuels using various process intensification strategies for the development of a clean and green environment is reviewed in this study. The synthesis of types of perovskite catalysts polycrystalline, nano-sized, and powdered oxide are also discussed in this review. It is also concluded that, apart from other process parameters, molar ratio is one of the most influencing sensitive factors in the case of 1st generation biofuel synthesis, whereas during the production of 2nd generation biofuels, catalyst concentration and liquid–solid ratio are more significant process parameters that change based on the nature of the catalyst selected for the reaction.

Polymeric flocculation is widely used to accelerate the dewatering and consolidation of oil sands fluid fine tailings (FFTs). Optimizing flocculation requires a fundamental understanding of the changes to the internal structure of the material with polymer addition. Key challenges include sensitivity of flocculation to polymer dose, mixing conditions, and composition of individual FFTs. Moreover, despite the environmental implications, little is known of the effects of flocculation on the mobility of the residual organics present in the tailings. In this paper, advanced rheological tests are used to probe the formation and development of the polymer–clay structure during flocculation in near-real time. This is achieved through a novel setup for controlled delivery of the polymer directly into the measuring cell of a rheometer. This enables continuous monitoring of the rheological parameters during the flocculation process and yields consistent and reproducible samples. An optical monitoring system is used to relate rheological measurements to water release and to changes in the surface accumulation of the residual bitumen. The water-release polymer dose is found to be associated with a distinct rheological response highlighting the potential use of rheometry for polymer dosing/mixing optimization in real time and on a continuous basis in thickeners and inline flocculation systems.

The optimum conditions needed to separate phosphorus from the lime mud generated in kraft pulp mills were identified using different leaching solutions including carbonate, bicarbonate, and green liquor under variety of conditions. Carbonate ions seemed to be the active ion in the phosphorus leaching process. Bicarbonate solution seems to be the most effective leaching agent by removing 84% of phosphorus under the optimum operating conditions of 95°C, 2.92 m, and solution-to- mud mass ratio of 3.6. The shrinking core model was used to determine the leaching mechanism and it showed that the leaching process is controlled by a mix of chemical reaction and diffusion through the particle. Two empirical models were developed to predict the leaching efficiency as a function of carbonate concentration and temperature. Counter-current leaching was shown to be beneficial in increasing the leaching efficiency with the carbonate solutions.