International Journal of Chemical Engineering

Recently, there is a growing demand towards adopting 3D printing technology in various sectors due to its potential merits. The mechanical properties and surface quality of the final product are influenced by the process parameters. Therefore, this study aims to optimize the infill density and pattern beside printing speed and temperature to achieve optimum mechanical properties and surface characteristics of PLA+ 3D-printed material. The Taguchi method was applied with L9 array, and tensile and surface roughness tests were carried out to evaluate the performance of specimens in terms of the obtained ultimate tensile strength, Young’s modulus, tensile strain (%), and surface roughness. The selected parameters with their levels were as follows: printing temperature (205, 215, and 225°C), printing speed (20, 50, and 80 mm/s), infill density (30%, 60%, and 90%), and infill pattern (triangle, cubic, and concentric). The findings revealed the significant impact of the infill density followed by the infill pattern on the mechanical and surface performances of the PLA+ material. From the other side, the Taguchi method was integrated with grey relational analysis (GRA) as a multiobjective optimization to find out the optimum mechanical properties and surface characteristics of the 3D-printed PLA+ part. Accordingly, 215°C, 50 mm/s, 90%, and triangle pattern achieved optimum mechanical properties (24 MPa, 3.14 GPa, and 13.72%) and surface roughness (3.21 µm).

This paper addresses the analysis of hydrothermal carbonization of Tetra Pak residues using diluted sulfuric acid to obtain hydrochars for cleaning water polluted by heavy metal ions. The hydrochar samples were prepared under different carbonization conditions, and a detailed study of their composition, textural parameters, and surface functionalities was performed. It was found that the hydrothermal carbonization and dwell time of the Tetra Pak wastes significantly affected the composition of the hydrochars. These hydrochar samples contained oxygenated functional groups and aluminum-silicon moieties that were responsible for the Pb²⁺, Zn²⁺, and Hg²⁺ adsorption. The removal of these heavy metal ions using Tetra Pak hydrochars was an endothermic and multi-ionic process. Hydrothermal carbonization is a promising approach to improve Tetra Pak waste management, generating materials with interesting properties for addressing the problem of wastewater and industrial effluent depollution.

Canals are a very imperative source of irrigation for the agricultural sector in India. Seepage causes major water loss in canals, and hence, the installation of liners becomes necessary. Compacted clay soils are commonly used as liners in the canals. This structure will most probably be subjected to salinization and desalinization cycles throughout its life. Because of the interaction between the pore liquid and clay particles, physico-chemical influences considerably impact the behavior of clay barriers. In this paper, the effect of interacting fluid on volume change, consolidation parameters, and hydraulic conductivity of compacted clay soil is investigated with the help of a one-dimensional consolidation test. The compacted clay specimens were immersed alternatively with distilled water (DW) and sodium chloride (NaCl) solutions (SW) at constant loading of 10 kPa, which replicates the load conditions in the field canal due to 1 m head of water and incremental loading as per IS 2720 part 15 standards. The experimental results proved that there is a percentage volume change increase of about two times for each stage inundated with 4M NaCl solution than its preceding stages inundated with distilled water at constant loading of 10 kPa. The consolidation rate was accelerated with 4M NaCl solution than the normal consolidation at incremental loading. The permeability coefficient in the salt water-induced sample increased by 217% more than the distilled water-induced sample at incremental loading. Therefore, the soil specimen subjected to alternate salinization and desalinization cycles significantly affects the volumetric and consolidation behavior, leading to decreased life of clay barrier structures.

Oxidative coupling of methane and methane dehydroaromatization are attractive one-step conversion routes to make valuable platform chemicals more sustainable. Both processes require elevated temperatures above 600°C, good heat management, and the use of heterogeneous catalysts. None of these reactions are yet commercial due to many technical challenges. This work explores the potential of combining these two processes under one umbrella to overcome some of the technical challenges and make these processes more attractive. It focuses on the recuperative autothermal reactor coupling as one of the possible integration options. A tube-in-tube reactor design is proposed in which OCM is in the inner tube and MDA is in the outside. A numerical study is carried out using pseudohomogenous ideal fixed bed reactor models with literature kinetics. A systematic tabulated approach is used to simplify, visualize, and structure the design process and view the design options. Practical constraints such as reactor sizing, pressure drop, reaction performance, and axial temperature profile are investigated. The effect of heat transfer coefficient, diluents, catalyst profiling, and flow direction have been investigated to alter the axial temperature profile, avoid thermal run away, and improve the performance. Multiple thermally coupled OCM-MDA reactor design candidates are identified. This is the first time that the thermal coupling of OCM and MDA has been identified and quantified. These candidates are merely a starting point toward exploring the full coupling opportunities between OCM and MDA toward reaching the ultimate and more attractive option of full mass and heat integration in the same reactor.

Almost every metal and alloy corrodes when used in high-temperature applications. To combat this problem, ceramic coatings on the metals can be deposited for better thermal and corrosion behavior. The present study applies an alumina-titania (Al₂O₃-TiO₂) ceramic coating to the stainless steel (SS) surface using a detonation spray process. The surface of the coated SS is probed by optical microscopy (OM), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The clear differences between coated and uncoated SS have been observed based on the SEM images. The XRD pattern indicates that the Al₂O₃-TiO₂ coating on SS has been successfully deposited. The hardness of coated and uncoated SS surfaces is determined by using the Micro Vickers hardness tester, which claims that the hardness of the SS surface has decreased after coating. Salt spray tests were used to examine the corrosion behavior of coated and uncoated SS after 12 and 24 hours. After 12 hours, no corrosion was observed on the SS. After 24 hours, however, significant corrosion of uncoated SS is observed, and the coated SS shows negligible corrosion. Based on the study, it is claimed that an Al₂O₃-TiO₂ coating on SS has improved its corrosion behavior significantly.

In this study, we performed a comparative analysis of the combustion behavior of pyrite, pyrrhotite, and pyrite-pyrrhotite mixture (mixed mineral) powders in an air atmosphere. To study the influence of the pyrrhotite content in mixed mineral powders on the combustion behavior in the air, thermogravimetric mass spectrometry, X-ray diffraction analysis, and scanning electron microscopy were employed. The results indicated that pyrrhotite lead to a weight gain in the mixed minerals during the combustion process. Pyrrhotite particles are more easily adsorbed on the surface of pyrite particles during mixed mineral combustion due to their strong ability to absorb oxygen, which accelerates pyrite combustion. The weight loss of mixed minerals decreased during the combustion process with increasing pyrrhotite content, resulting from pyrite encapsulation by agglomerated and sintered pyrrhotite during combustion. The calculated kinetic parameters and phase analysis results suggested that pyrite combustion is consistent with the shrinking core mechanism, and in the combustion process, the irregular pyrite particle shrank into a spherical particle; the combustion products of pyrrhotite grew in a layer-by-layer manner. Pyrrhotite combustion corresponded to the three-dimensional diffusion mechanism, and mixed mineral combustion was dominated by the shrinking core mechanism and supplemented by the three-dimensional diffusion mechanism. SO₂, as the main combustion product, was continuously generated and volatilized in the reaction, signifying that the combustion reaction of pyrite is a two-phase reaction involving gas and solid.