South African Journal of Chemical Engineering最新文献

The utilization of activated carbon as an efficient adsorbent is well-established, driven by its porous structure and expansive surface area. This study investigates the potential of Cassia fistula (Golden shower) as a precursor for activated carbon synthesis using K₂CO₃ activation, leveraging its organic properties known for high porosity and adsorption capacity. This research aims to investigate the feasibility of utilizing Cassia fistula-derived activated carbon (GSAC) for isoniazid removal from water. The study encompasses a two-step activation process—chemical and physical—with varying parameters to optimize surface area and porosity. The carbonization process involves hydrothermal and pyrolysis techniques with controlled conditions. The temperature used in this study is based on the TGA analysis to examine its thermal stability. Batch experiments examine the adsorption equilibrium and kinetics of isoniazid onto GSAC samples, revealing high adsorption capacity and rapid equilibrium attainment by GSAC 1:1 (700°C). The study culminates in the identification of a strong chemical bond between GSAC and isoniazid, implying efficient adsorption potential as confirmed by FTIR and SEM analysis before and after adsorption. The adsorption characteristic is examined with an isotherm and kinetic model. The highest predicted GSAC capacity reaches 219,807 mg/g, emphasizing its promising adsorption capabilities. This work underscores Cassia fistula-based activated carbon as a viable, cost-effective, and eco-friendly adsorbent for isoniazid removal, with implications for diverse applications. The synthesis process parameters, activation methods, and insights into the adsorption mechanism contribute to the understanding of effective adsorbent production and enhance the potential of activated carbon for various industrial contexts.

Most antibacterial air filters show good performance for single-use. However, reusable ones are also essential for reducing cost, emergency use, and environmental reduction waste, which are still less attention by researchers. This study investigated the reusability and regeneration capabilities of air filters containing zinc oxide nanoparticles immobilized on white silica gel beads coated with chitosan (ZnOChSi). TEM confirmed nanoparticle size of 11.5 ± 2 nm and dispersed particles. Bacteria-containing spore (Bacillus subtilis) was used to investigate the antibacterial properties of the air filter. The reusable ZnOChSi air filter showed antibacterial properties up to the fourth cycle (4 × 48 h) with >20% efficacy and was no longer practical for the fifth cycle. The regenerated ZnOChSi air filter still performed relatively high antibacterial properties until the third cycle (3 × 48 h) with >50% efficacy and was slowly decreased for continued use. This regeneration test confirmed that the cleansing (heating) method carried out once after 2 × 48 h re-activated the antibacterial properties of the filter. The zinc content release was 1.186 mg/L (0.012% from 10.245 g of the zinc oxide filter).

Teeter bed separator has gained significant importance and appeared as a viable option for beneficiation of high alumina and low iron content Indian iron ore fines. Modelling particle separation in a Teeter bed separator from the first principles of particle mechanics and fluid dynamics has been challenging due to the complex interactions of forces acting on particles in varying flow regimes. So, the size recovery curve is a viable option for assessing the separation performance of this separator. This investigation systematically examines the suitability of the Teeter bed separator in reducing the alumina content in Indian iron ore fines. Thorough experimentation and statistical analysis confirm the separator's suitability for beneficiation. Careful consideration was also exercised in choosing a suitable mathematical model to characterize mineral size recovery curves. In this research work Modified Hyperbolic Tangent model, Hyperbolic Tangent model, Weibull model, Rosin-Rammler type model, Erasmus model, and Power function model have better fitted for size recovery. Out of which the Modified Hyperbolic Tangent models for all the data sets indicated the better ability to fit the size recovery data than other models. This innovative approach aligns with the principles of circular economy, aiming to optimize resource utilization and minimize waste throughout the production process. Furthermore, a suitable mathematical model is selected to represent the size recovery curves for minerals by adopting the statistical analysis approach to describe the process. The results may pave the way for the Indian iron ore beneficiation process to increase production yield and improve product quality for low-grade iron ore utilisation.

The investigation focused on exploring the potential applications of the BN nanocage (B₁₂N₁₂) as both an adsorbent and a sensor for removing and detecting fosfomycin (FM) using density functional theory computations. In this respect, the interaction of FM with B₁₂N₁₂ was evaluated at 3 different configurations and the most stable one was determined. The results showcased the interaction between FM and B₁₂N₁₂, highlighting the feasibility, exothermic nature, and spontaneity of the interaction, emphasizing the effectiveness of B₁₂N₁₂ as an FM adsorbent. Moreover, the study scrutinized the influence of water as a solvent and different temperatures on the thermodynamic parameters. Interestingly, the results indicated that these factors had negligible impacts on the interactions. Nonetheless, it was noted that the interactions were a bit stronger in vacuum and at lower temperatures. Additionally, the Frontier Molecular Orbital (FMO) analysis exhibited a bandgap of 6.716 eV for B₁₂N₁₂, which increased by approximately 90 % to 13.381 eV upon FM adsorption, indicating a significant reduction in the electrochemical conductivity of BN nanocage during the FM adsorption process, thereby hinting at its potential use as an analytical signal for the electrochemical detection of FM.

The rise in carbon dioxide concentration is a primary anthropogenic source of severe climate change and ecological issues. Catalytic hydrogenation of CO₂ into value-added chemicals and fuels including methanol is one of the attractive environmentally friendly ways to valorize carbon-containing feedstock and reduce global CO₂ emissions. However, enhancing catalytic activity to achieve high methanol yield and selectivity while maintaining stability remains a major challenge. This study investigated the promotion of Cu/MOF-5 catalysts with varying loadings of ZrO₂ to determine its effects on catalytic performance in CO₂ hydrogenation. The copper loading was kept constant while the ZrO₂ content on the MOF-5 support was varied via the impregnation method. The addition of ZrO₂ was found to influence the BET surface area, suggesting the presence of amorphous ZrO₂, as its crystalline phases were not detected in x-ray diffractograms. Catalytic results demonstrated that ZrO₂ addition enhanced the catalytic activity, with increased CO₂ conversion up to 13.2 %. The results showed a correlation between catalytic performance and the reducibility of the active metal, driven by the amount of ZrO₂ present. The catalyst with the highest ZrO₂ loading exhibited the best performance, attributed to its increased surface area and enhanced reducibility. Under optimized conditions (GHSV of 1350 h⁻¹, temperature of 200 °C, and pressure of 30 bar), the catalyst achieved 100 % methanol selectivity. This study underscores the significant role of ZrO₂ as a promoter in enhancing the activity and selectivity of Cu/MOF-5 catalysts, providing critical insights into the design of efficient catalytic systems for CO₂ hydrogenation.

The swelling method constitutes a component of the hierarchical synthesis step of Natural Zeolite Lampung (NZL). The literature review results indicate that NZL swelling is a pretreatment integral to the synthesis process of NZL. The synthesis of Lampung natural zeolite (NZL) was conducted to form hierarchical zeolites. NZL, as a hierarchical zeolite, is defined as a system containing additional pores. The formation of secondary porosity distinguishes it, reduction of alkali and alkaline earth metals, removal of impurities, transformation of symmetric to asymmetric strains, increase in acidity, and most importantly, the occurrence of dealumination and desilication processes as the cause of the achievement of these indicators. Generally, the initial post-synthesis modification sequence, which typically involves acid and base treatment, is carried out separately. In this study, however, the dealumination and desilication modifications will be carried out simultaneously in a single process, namely by the swelling method. Consequently, it is essential to ascertain the optimal operating parameters at the requisite atmospheric pressure, thus enabling the simultaneous dealumination and desilication processes within the NZL swelling method. In this case, the swelling method is a pretreatment analogous to the initial zeolite activation conducted in previous studies. The swelling NZL method can potentially overcome the laborious and expensive synthesis procedures that currently limit the scale-up of this material into large-scale production.

Fingerprint powder remains one of the most effective techniques for identifying individuals from their latent fingerprints. Visualizing latent fingerprints requires powder with high color contrast and strong adhesive to be easily applied on various substrates. The utilization of silica gel extracted from local materials of Lapindo volcanic mud can be applied for fluorescent fingerprint powder based on methyl orange. The powder was synthesized by the sol-gel method, followed by the impregnation of methyl orange as a dye with varying loads. The powders exhibit an amorphous structure and nanoparticle size with an average particle diameter of 80.93 nm by spherical morphology interconnected to form agglomerations. The powder contains silanol, siloxane, azo, and carboxylate functional groups derived from its precursors. The dusting method proves the performance of fluorescent fingerprint powder on porous and non-porous substrates hereafter observed under white light and UV light. The powder containing 0.05 gs of methyl orange per gram of silica gel is the most effective in revealing fingerprint patterns on non-porous surfaces. It has mesoporous properties with a specific surface area of 7.95 m²g⁻¹ and a pore diameter of 23.14 nm. SiMO retained its full capability after two years of storage, indicating it is a great choice for forensic investigations.

Topological indices play a crucial role as molecular descriptors in QSAR/QSPR research. Graph entropy measurements are of great importance in various fields like chemistry, discrete mathematics, and biology. Information-theoretic values derived from topological indices, influenced by Shannon’s entropy, are used to analyze the structural characteristics of chemical graphs and complex networks. We discuss the analysis of graph entropies obtained from a new information function. It is equivalent to both the total number of edges and the various degrees of vertices. The information function is also employed to compute the entropies of the system and build a connection between connectivity indices and degrees. This study examines the chemical graphs of Carboxylate-terminated Zinc Phthalocyanine (CtZP) and Nanostar (NS), using the function to connect degree-based topological indices like First Zegrab index, Second Zagreb index, Hyper Zagreb index, Forgotten index, First Redefined Zagreb index, The Second Redefined Zagreb index, The Third Redefined Zagreb index, and Somber index, to calculate the entropies of these structures.

This study aimed to preserve the quality of chikuwa during storage through the application of an edible coating derived from a combination of liquid smoke extracted from young coconut shell pyrolysis and chitosan. Liquid smoke was obtained through pyrolysis at temperatures of 300 °C (T1), 340 °C (T2), 380 °C (T3), and 420 °C (T4), followed by distillation to remove tar and other contaminants. A solution comprising 2 % liquid smoke was utilized to dissolve chitosan (0.5–1.5 % w/w), creating an edible coating, which was then applied to chikuwa samples through a 15-minute immersion process. Throughout the storage period, the quality of the chikuwa was evaluated using total volatile base nitrogen (TVB-N), total plate count (TPC), most probable number (MPN) Escherichia coli testing, as well as minimum inhibitory concentration (MIC), and minimum killing concentration (MKC) tests against Gram-negative bacteria (E. coli and Salmonella enterica sv Typhimurium). Results from the TVB test indicated that chikuwa treated with an edible coating, particularly at T4, maintained freshness for up to 168 h. Microbiological analyses revealed that TPC and MPN E. coli values remained compliant with Indonesian National Standards (SNI) for up to 120 h of storage in T4-treated samples, with values of <4.72 × 10⁴ CFU/g and 460 MPN/g, respectively. Furthermore, MIC and MKC values demonstrated the inhibitory and bactericidal effects of young coconut shell liquid smoke against E. coli and S. typhimurium. Overall, the findings suggest that the application of an edible coating effectively mitigates the deterioration of chikuwa quality during storage, extending up to 120 h.

In the present research, an effort has been made to analytically solve heat and mass linear/ nonlinear as well as steady/ unsteady equations in a viscous nanofluid squeezed between parallel sheets. Using Python and the SymPy library, the nanofluid with viscous properties between parallel sheets has been analyzed to symbolically solve flow, heat, and mass transfer effects equations through the Homotopy Perturbation Method and Akbari-Ganji Method approaches. The two nanofluids selected to conduct this study are Copper as well as $A{l}_2{O}_3$, whose sizes are 29 nm and 47 nm respectively. The provided details encompass the outcomes of active variables on flow and the transfer of heat coupled with mass. The Homotopy Perturbation and Akbari-Ganji methods have resulted in top-of-the-line consequences compared to analytical and numerical approaches. This research study highlights a faster and more accurate computation to conduct the analytic section of the study. The outcome shows that the increase of the Prandtl number and the Eckert number will increase Nusselt. However, skin friction increases with the increase in the Schmidt number. Furthermore, a rise in Schmidt number and parameters related to chemical reactions leads to an elevated Sherwood number. The outcomes of the study presented here provide a more innovative and precise insight, and the comparison with the available literature also proves there is a well-agreed numerical calculation. Microchips in engineering and medical-related industries would enjoy the outcomes obtained from this study. This study proves that the maximum and minimum amounts of heat transfer in respect occur at $\eta =$0 and $\eta =1$. Moreover, the maximum and minimum amounts of error are equal to 0.0001 and 0.00001, respectively. The maximum and minimum amounts of concentration occur at $\eta =$1 and $\eta =0$ in order. Finally, the maximum and minimum amounts of error are equal to 0.000016 and 0.000002, respectively.