Band 116, Heft 7

In this work, we investigate the efficiency of different pretreatment methods and their impact on the characteristics of cellulose nanocrystals (CNC) extracted from the Diss plant, a widely available plant in the North African region. Two extraction methodologies were employed, focusing on the effects of bleaching treatments using hydrogen peroxide and sodium chlorite. Fourier transform infrared spectroscopy confirmed the effective removal of non-cellulosic materials, yielding CNCs with a cellulose I crystalline structure. The Zeta potential analysis revealed an increased presence of hydroxyl groups on the CNC surface. Scanning electron microscopy showed that CNCs tend to form agglomerates upon drying. Thermogravimetric analysis demonstrated that the CNCs exhibit considerable thermal stability, with degradation temperatures ranging from 100 °C to 350 °C.

This study investigates the development of biodegradable bio-composites made from polylactic acid (PLA) reinforced with farm waste materials, specifically coconut shell powder and jackfruit skin powder. The bio-composite filaments were fabricated using a filament extruder, and the samples were created through fused deposition modeling (FDM). Mechanical strength, water absorption, and flammability were evaluated. The results revealed that incorporating coconut shell (CBC) and jackfruit skin (JBC) powders into the PLA matrix significantly enhanced the mechanical properties, water resistance, and flame retardancy of the composites. The hybrid bio-composite (HBC) showed a 73.7 % improvement in water absorption resistance, with a water absorption rate of 9.06 ± 0.02 %. CBC and JBC demonstrated 70.8 % and 67.2 % reductions in water absorption, respectively, compared to pure PLA. The HBC bio composite also exhibited superior flame retardancy, with a 60.9 % increase in ignition delay (8.43 ± 0.21 s), 30.5 % reduction in flame spread rate (43.21 ± 1.42 mm min −1 ), and 50.5 % increase in after-flame duration (13.14 ± 1.05 s). In terms of tensile properties, HBC outperformed all other composites with an ultimate tensile strength (UTS) of 59.2 ± 1.8 MPa, representing a 44.2 % improvement compared to pure PLA. The CBC and JBC showed 24.7 % and 10.7 % increases in UTS, respectively. The HBC also showed a 40.2 % improvement in flexural strength, with the lowest deflection at 4.0 ± 0.1 mm, compared to 23 % and 20.8 % improvements for CBC and JBC, respectively.

In this study, highly crystalline orthorhombic chromium carbide (Cr 7 C 3 ) nanoparticles were synthesized via a lithium thermal reduction route under mild conditions. The reaction was conducted in a stainless steel autoclave at 500 °C, using chromium sesquioxide (Cr 2 O 3 ), metallic lithium, and waste polytetrafluoroethylene (PTFE) as raw materials. When Cr 2 O 3 was replaced with other chromium sources, such as chromium trioxide (CrO 3 ), potassium dichromate (K 2 Cr 2 O 7 ), or ammonium dichromate ((NH 4 ) 2 Cr 2 O 7 ), Cr 7 C 3 could also be obtained through a similar procedure. This demonstrates a general and convenient approach for synthesizing crystalline Cr 7 C 3 using waste PTFE as a carbon source. This method not only provides a novel low-temperature route for Cr 7 C 3 preparation but also offers a sustainable strategy for recycling waste plastics.

The uncontrolled release of synthetic dyes into aquatic ecosystems poses a significant challenge, requiring the development of effective and eco-friendly methods for wastewater treatment. In this pioneering study, we explore the untapped potential of Ixora coccinea leaf as a natural adsorbent to tackle the removal of methylene blue (MB) from aqueous solutions, offering a sustainable and efficient solution for wastewater purification. Through a systematic series of experiments encompassing various pH levels, contact times, and adsorbent dosages, we unravel the remarkable adsorption capabilities of I. coccinea leaf, transforming it into an invaluable resource for combating methylene blue contamination. The results demonstrate an exceptional affinity between the I. coccinea leaf and methylene blue, defying expectations and surpassing conventional adsorbents. The equilibrium adsorption data conform fittingly to the renowned Langmuir isotherm model, indicating the occurrence of a monolayer adsorption process. Impressively, the maximum adsorption capacity is determined to be 9.26 mg g −1 , underscoring the unprecedented sorption potential of I. coccinea leaf in removing methylene blue. Optimizing the pH conditions is critical in the adsorption process, with an optimized pH range of 7.3 showcasing the peak efficiency of I. coccinea leaf as an adsorbent. Furthermore, an in-depth examination of adsorption kinetics reveals the dominance of the pseudo-second-order model, suggesting a chemisorption mechanism. The rapid rate of adsorption emphasizes the efficacy of I. coccinea leaf as a formidable adsorbent for treating wastewater laden with methylene blue. Exploring the molecular interactions, Fourier-transform infra-red analysis unravels the intricate involvement of various functional groups in driving the adsorption process. Additionally, scanning electron microscopy images vividly depict the morphological changes occurring on the adsorbent surface. This groundbreaking exploration of I. coccinea leaf’s potential invites us to embrace its versatility in sustainable wastewater treatment. The extraordinary attributes of I. coccinea leaf transcend traditional methodologies, offering an eco-friendly and cost-effective solution for large-scale adsorption processes. The optimization of regeneration techniques and further research are encouraged to fully exploit the practical feasibility of this natural wonder for industrial applications. By harnessing the power of I. coccinea leaf, we embark on a transformative journey toward preserving our environment, ensuring a cleaner and healthier future for generations to come.

The large volume of water produced alongside crude oil during extraction is a significant challenge in the oil and gas industry. Since crude oil emulsions can have a pH ranging from 2 to 13, inhibitors effective in acidic, basic, and neutral media are essential for reducing the corrosion rate of transportation lines. This paper aims to elucidate the capability of corrosion inhibition of 1, 3-diphenyl prop-2-en-1-one, a chalcone on mild steel corrosion in near acidic, neutral, and near basic media using 1  N HCl, 3.5 % NaCl and 3.5 % NaCl with 0.1  N NaOH made up to pH 8.5. The inhibitive competence of the inhibitor was determined by gravimetric, potentiodynamic polarization, and electrochemical impedance spectroscopic studies. Nuclear magnetic resonance spectroscopy was used to characterize the carbon and hydrogen environment of the synthesized chalcones. The proposed inhibitor was found to give a good inhibition efficiency of 98.7 % in acidic media and a reasonable decrease in corrosion rate in basic and neutral media. As the concentration of the inhibitor increases, the efficiency of inhibition increases, whereas, the efficiency decreases as the temperature increases. Potentiodynamic polarization confirmed that the inhibitor is of the mixed type. Impedance analysis explains the presence of an inhibitor as an adsorbed layer by a change in resistance and inhibition efficiency. The adsorption mechanism of the inhibitor on the mild steel surface is found to obey Langmuir’s adsorption isotherm.

The microstructures, mechanical properties, and creep resistance of Mg‐9Al‐1Zn‐0.6Sr‐ x La ( x = 0, 1, and 2 wt.%) alloys produced by cold-chamber high-pressure die casting were exhaustively studied in this paper. The obtained experimental results showed that the main alloy (Mg‐9Al‐1Zn‐0.6Sr) consists of α-Mg, β-Mg 17 Al 12 and Al 4 Sr intermetallic phases. In addition to these phases, an Al 11 La 3 intermetallic phase was detected in the Mg alloys containing La. Furthermore, while the diffraction peak intensity of Al 11 La 3 was gradually raised with increasing La addition, the formation of the β-Mg 17 Al 12 phase was suppressed. The mechanical properties of the main alloy were obviously improved with rising La addition at room temperature and elevated temperatures. Similar progress was exhibited on the creep resistance of the main alloy.

Brass/steel multilayer composites were fabricated using the accumulative roll bonding technique, with notable microstructural features including lenticular configurations and homogeneously dispersed steel. The outcomes of the tensile testing indicated that the composite processed through eight accumulative roll bonding passes achieved a tensile strength of 817.6 MPa, which is 2.7 times greater than that of the original steel and brass sheets. Analyses conducted via scanning electron microscopy revealed the presence of shear dimple rupture, cleavage, and lamellar fracture modes on the surfaces of the fractures. The observed weight loss and coefficient of friction were found to escalate with increasing load. Predominant wear mechanisms identified included abrasion, delamination, and plastic deformation.

Mechanical as well as microstructural properties are significantly affected due to structural integrity issues. Pipeline steel transporting oil/gas and large storage tank carrying hazardous products are prone to failure due to structural integrity issues. In the present work an attempt has been made to study the effect of S4–C504 filler metal on the mechanical and microstructural properties of American Petroleum Institute (API) X70 and SA 516 structural steel dissimilar weld joint fabricated by metal inert gas welding (MIG). Impact toughness, hardness and microstructure of X70 + SA516 dissimilar weld joint were studied. The microstructure of SA 516 is basically a blend of ferrite and pearlite with grain boundary ferrite films dispersed in ferrite matrix. X70 basically exhibit a ferritic–pearlitic microstructure with some precipitates of martensite–austenite dispersed along the ferrite boundaries. The heat affected zone (HAZ) microstructure on the API X70 side shows the partially unmixed region with some inclusions of ferrite embedded across the grain boundaries. For X70 base metal, maximum hardness of 36.75 HRC was observed in the HAZ region whereas minimum hardness of 32.5 HRC was noticed in the HAZ region along the SA516 base metal side of the SA516 + X70 weld.