Mild Carbon Research Articles

Enhanced photo-oxidation of hormones in water using biomass waste-derived hydrochar composites as photocatalysts

This study introduces a green chemistry approach to enhance the catalytic efficiency of metal oxides in photocatalytic reactions using agro-industrial waste. Specifically, rice husks and spent coffee grounds were utilized as carbon sources to produce hydrochars, which served as sustainable supports for ZnO and ZnFe₂O₄ oxides. This method promotes waste minimization and circularity by repurposing agricultural byproducts, reducing the environmental impact of traditional catalyst production. The hydrochars were synthesized through mild hydrothermal carbonization (250 °C for 4 h) and characterized by various physicochemical analyses. Their photocatalytic performance was evaluated using a 20 mg L−1 solution of conjugated estrogens under ultraviolet light (120 W cm−2) for 30 min. Composites with ZnO exhibited a significant increase in oxidation reaction rates due to enhanced porosity and an oxygen-rich structure. Reactive oxygen species (ROS) analysis revealed hydroxyl radicals (OH) as the primary agents, with photocatalytic efficiencies exceeding 83 % after eleven cycles. In toxicity tests, 4 mL of treated solution was applied to 20 Lactuca sativa (lettuce) seeds, kept in the dark at 25 °C for 7 days. Seeds exposed to treated solutions showed improved radicle elongation and germination rates compared to controls, except for those with coffee hydrochar and ZnO. This indicates effective degradation of toxic estrogens without harmful by-products. Overall, this work highlights the advantages of integrating green chemistry principles and circular economy practices, transforming waste into valuable materials to enhance environmental sustainability and catalytic performance.

Behaviour of Dissimilar Welded Connections of Mild Carbon (S235), Stainless (1.4404), and High-Strength (S690) Steels under Monotonic and Cyclic Loading

Behaviour of Dissimilar Welded Connections of Mild Carbon (S235), Stainless (1.4404), and High-Strength (S690) Steels under Monotonic and Cyclic Loading

PEMFC AST Protocol for Air-Air Starts: Screening of Cathode Tolerances

The long-term durability of the cathode catalyst layer continues to be one of the main obstacles for the widespread commercialization of proton exchange membrane fuel cells (PEMFCs) for transportation applications. A major challenge is air/air-start events that occur after long shut-down periods where an H2/air gas front passes through the anode and causes polarization of the cathode electrode to ≈1.4-4.5 V. To screen catalyst materials for their air/air-start tolerance, several accelerated stress test (AST) protocols have been developed. The two most commonly used AST protocols have been recommended by the U.S. Department of Energy (DoE): (1) catalyst support protocol consisting of triangle sweep cycles: 500 mV/s between 1.0 V and 1.5 V (H2/N2, 80ׄ°C, 100% relative humidity (RH)) designed to trigger corrosion of the carbon support; (2) unmitigated start-up/shut-down durability protocol involving an H2/air front, whereby each cycle consists of a start-up event, intermittent fuel cell operation, an unmitigated shut-down event, and an idle period under relevant air/air-start conditions (35°C, 100% RH). While the second protocol is a closer representation of air/air-start events that occur in a PEMFC system, it requires specialized fuel cell testing equipment to allow for an H2/air front in the anode electrode. Conversely, the triangle sweep protocol can be used for catalyst benchmarking on any fuel cell test bench and even in model systems like rotating disc electrode (RDE), or gas diffusion electrode (GDE) setups.In this work, we compared H2/air front-based start-up/shut-down (SUSD) aging to the voltage-controlled carbon corrosion AST for four catalyst coated membranes (CCM). Using in-situ electrochemical and ex-situ characterization techniques (e.g., μXRD, SEM, and TEM), the degradation is compared with respect to the rate of loss in the electrochemically active surface area (ECSA). Particularly the correlation between voltage losses and ECSA, Pt particle size growth, catalyst layer thinning, and homogeneity of aging were investigated. Our results with the catalyst support AST confirms that this method exclusively triggers the carbon corrosion aging mechanism without a significant increase in the Pt particle size and is therefore a suitable screening protocol for support stability. However, the more application relevant SUSD protocol resulted in a combination of comparatively mild carbon corrosion and severe Pt dissolution/redeposition that caused significant Pt size growth and Pt band formation. Furthermore, SUSD resulted in inhomogeneous aging where the Pt size growth is more pronounced towards the anode inlet of the CCM. Due to the difference in the dominating aging mechanisms, the voltage loss response at nominally the same loss of ECSA varies greatly for the two protocols. Therefore, typical voltage-controlled AST (1-1.5V) is found to be unsuitable for predicting the air/air start tolerance of catalyst material. Instead, we propose to use an alternative voltage-controlled protocol that combines the two main degradation mechanisms of air/air starts: triangle sweep cycles at 500 mV/s between 0.7 V and 1.4 V (H2/N2, 45ׄ°C, 100% relative humidity).

Investigation into Morphology of Cavitation Erosion-Corrosion Pits on the Surface of Carbon Steel

Nano-sized films associated with the ring areasformed around micropits in cavitation erosion experimentswere investigated. The corrosion behavior and vibratory cavitation erosion tests of mild carbon steel in 3% NaCldistilled water were carried out. The results showed that thenano-sized films associated with the ring areas formedaround micropits in cavitation and free cavitation tests havea similar shape. The study proved that the nano-structure and the ring areas formed around micropits are the result ofcorrosion effects and not as a result of thermal effectsrelated to the collapse of the bubbles.

Performance of carbon nanomaterials incorporated with concrete exposed to high temperature

Abstract In recent decades, there have been initiatives to incorporate carbon nanomaterials (CNMs) into cement composites, particularly graphene oxide (GO), carbon nanotubes, graphite (GP), and mild carbon (MC). Nevertheless, little is known about how these CNMs interact with the cement matrix itself. In this research, the impact of CNM incorporation at high temperatures (250, 500, 750, and 1,000°C) on cement’s mechanical characteristics and microstructure was investigated. Nine mixes were created with the CNM content (0.1 and 0.3%) being taken into consideration. The microstructure of the CNM composites was further investigated using X-ray diffractometry, thermogravimetry, derivative thermogravimetry, digital microscopy, and micro-computed tomography (micro-CT). Based on research observations, the study demonstrated that the mechanical properties of most specimens could be enhanced through the introduction of CNMs. The recommended proportions of GP-0.1, GO-0.1, and MC-0.1, in accordance with the weight of the binder, and the impact of the CNMs on the elastic modulus were also assessed. As a consequence, the CNM’s porous structure and apparent crack pattern were identified using microstructure analysis.

Corrosion Inhibition Performance of Whey Protein-Derived Inhibitors for Low Carbon and Dead Mild Steels in1M Hydrochloric Acid

This research investigates the corrosion inhibition capabilities of BCAA-derived inhibitors for low-carbon steels and dead mild carbon steels with distinct carbon contents when exposed to a 1M HCL solution. The effectiveness of the inhibitors was evaluated by measurements of weight loss and polarization. The study revealed that at a concentration of 10 grams, the weighing method showed that the BCAA inhibitor showed protection effectiveness (87 percent) at 313 K for low carbon steel and (89 percent) effectiveness at 303 K for dead carbon steel. Using a concentration of 15 g, the polarization method showed inhibitory activity of (96 percent) at 313 K for low-carbon steel and (96 percent) at 303 K for dead light carbon steel. These results indicate that the inhibition efficiency is affected by the carbon content. Samples were subjected to scanning electron microscopy (SEM) and optical microscope analysis before and after adding the inhibitor. When examined using FTIR spectroscopy, BCAA showed significant efficiency as a corrosion inhibitor for steel alloys immersed in acidic conditions.

Performance Assessment of A Developed Rolling Mill

Rolling of metals has found applications in automotive, construction, agriculture, railroads, housing, metal furniture making, home appliances, electronic cabinetry, pipes and tubing etc. These have as well contributed to human and environmental sustainability. Nevertheless, the applications of metal rolling processes and machines have not been adequately harnessed in our locality due to unavailability of the rolling machine in small scale industries, laboratories and workshops in institutions of learning in the region. Annealing heat treatment was carried out on a mild steel round bar of 50 mm diameter and length of 200 samples. The samples were charged into an SXL muffle furnace with an annealing temperature of 950oC. The mechanical properties and the microstructure of the rolled mild carbon steel were evaluated. The results of the performance evaluation of the machine through assessment of the metallurgical characteristics of the rolled products from the machine and assessment of mechanical properties such as tensile strength and hardness of the rolled products from the machine showed an increase in the tensile strength from 250.85 MPa to 258.85 MPa, an increase in the ultimate tensile strength from 535.88 MPa to 540.05 MPa, an increase in the hardness from 140 HV to 145 HV, and a decrease in the percentage ductility of the mild carbon steel from 56% to 51%. Also, the optical micrograph of the rolled samples shows a coarse microstructure of grain refinement from slipping and pilling of dislocations.

Super Fe3+ competing ability, high biocompatibility, and mild antibacterial carbon dots for food preservation

Food spoilage caused by bacteria led to about 600 million people suffering from foodborne diseases in 2020, and the diseases kill approximately 400,000 people annually. Traditional food preservatives, antibiotics, and nanomaterials have problems such as high dosage, bacterial resistance, and low biocompatibility. In this study, mild antibacterial carbon dots (TM-CDs) with Fe3+ nutritional competitiveness were prepared. TM-CDs specifically chelated Fe3+ and formed Fe-O. The maximum chelating capacity of TM-CDs for Fe3+ was 154.56 mg mL−1. TM-CDs exhibited a much stronger chelating ability for Fe3+ than traditional iron chelators and even siderophores secreted by Pseudomonas fragi. The minimum inhibitory concentration of TM-CDs against Pseudomonas fragi was 0.25 mg mL−1. The antibacterial mechanism of TM-CDs was the existence of Fe3+ competition between TM-CDs and siderophores secreted by Pseudomonas fragi, which ultimately led to the death of Pseudomonas fragi due to iron deficiency. Notably, no obvious cytotoxicity of TM CDs was observed. In addition, the experimental results of freshness showed that TM-CDs effectively prolonged the shelf-life of salmon by 3–4 d. Therefore, this study provides insight into developing a competitive approach to depriving bacteria of nutrients for antibacterial purposes, with potential applications in seafood storage and preservation.

Carbon-in-carbon: Hybrid carbonized nanomaterials with multifunctional activities for the treatment of endophthalmitis

Infectious endophthalmitis (EO) is a severe eye condition characterized by inflammation of the eye’s internal fluids and tissues, often resulting from infection by bacteria or fungi. Patients with EO typically experience reduced vision, pain, and conjunctival infection. Despite the use of antibiotics, challenges such as inflammation and drug resistance remain. In this work, we have developed dextran/aliphatic diamines carbonized nanogels (DEX/ADA-CNGs) as board-spectrum antimicrobial agents by a one-step mild carbonization procedure. The CNGs exhibit not only antimicrobial properties but also show good drug delivery potential. Curcumin-based carbon quantum dots (Cur-CQDs) as an anti-inflammatory agent are loaded into DEX/ADA-CNGs to form hybrid carbon-in-carbon nanocomposites (Cur-CQDs@DEX/ADA-CNGs), showing combined antimicrobial, antioxidative, and anti-inflammatory activities. Impressively, CQDs@DEX/ADA-CNGs maintain strong antibacterial effectiveness against drug-resistant strains, with minimum inhibitory concentrations below 110 µg mL−1. The Cur-CQDs@DEX/ADA-CNGs have demonstrated high biocompatibility both in vitro and in vivo. In a rat model of EO, they rapidly (less than 5 days) reduce microbial infection and inflammation in the eye. Given these promising results, Cur-CQDs@DEX/ADA-CNGs show great potential as an enduring intravitreal treatment option for infectious EO.

Enhanced oxygen evolution reaction of electrodeposited Functionally-Graded Ni-Cu-Fe coating

This study aimed to use a functionally graded (FG) Ni-Cu-Fe coating as an electrocatalyst for oxygen evolution reaction (OER) applications. The coating was applied on a mild carbon steel substrate by an electrodeposition technique, with the current density being progressively increased from 0.5 A/dm2 to 5 A/dm2 at a steady rate of 0.2 (A/dm2)/min during the coating operation. Using this specific method, the Ni content of the FG Ni-Cu-Fe coating changed along the cross-section when increasing the current density, 17 % more than the constant current coating. This technique also affected the surface morphology of the FG Ni-Cu-‌Fe coating and changed it from cauliflower to micro/nanocones when the current density was linearly increased, enhancing active sites significantly and thereby improving electrocatalytic activity. The coating's electrocatalytic behavior was studied by electrochemical impedance spectroscopy (EIS), linear sweep voltammetry (LSV), and cyclic voltammetry (CV). results showed that the FG Ni-Cu-Fe coating had the smallest overpotential (134 mV) at the current density of 10 mA.cm−2. Also, it had the smallest Tafel slope (24.3 mV.dec− 1) and smallest resistance (598 Ω.cm2) compared to all of the other coatings. The FG Ni-Cu-‌‌Fe coating had higher OER performance because of high Ni content, micro/nanocones morphology with many active sites, and FG nature. The FG Ni-Cu-Fe coating is finally concluded to be a promising and economical catalyst with high OER activity.

Assessing the Technical and Economic Viability of Galvanizing Snow Crab (Chionoecetes opilio) Traps

Commercial harvesting of snow crabs (Chionoecetes opilio) began in Newfoundland and Labrador, Canada, in 1967. Today, the fishery consists of 2188 active fishing licenses and has grown into the province’s most economically valuable fishery. Snow crabs are captured using conical traps consisting of a mild carbon steel frame, hard plastic entry funnel and a jacket of polyethylene netting. The frames of these traps corrode over time, which is expedited by being deployed in marine environments and stored on land near the ocean when not in use. As a result, there is interest within the community to increase the longevity of crab traps. One solution is to galvanize the steel frames prior to installing the funnel and netting. However, before harvesters transition to galvanized traps, two questions must be answered. Will the use of galvanized steel negatively impact catch rates? Will the life cycle of a crab trap be extended sufficiently to justify the additional cost of galvanizing? This study employed a generalized linear mixed model to evaluate the catch of legal-sized male crabs (CPUE) during the commercial fishery as a function of three trap frame treatments (old traditional, new traditional and new galvanized). We also assessed the economic viability of galvanizing trap frames by evaluating the life cycle cost (LCC) of traditional and galvanized traps to the harvester. The LCC was calculated over a range of inflation (0–6%) and discount (3–20%) rates. Our results found no significant difference in CPUE between new traps (traditional vs. galvanized) and concluded that except during instances of very high discount rates (12.9–19.9%), it is economically favourable to galvanize crab trap frames.

Performance Evaluation of Strengthened Scrapped Mating Rings of Face Seals Used as Single Point Turning Tool

The scrapped mating ring of face seals has been studied and recycled into single point turning tools (SPTTs) and performed comparably with standard turning tools. Three sets of tools, namely, standard tungsten tool, strengthened and unstrengthened scrapped ring, have been studied and performed satisfactorily as SPTTs. Standard tungsten tool, strengthened and unstrengthened scrapped mating ring of face seal respectively. The tools were configured with a nose radius 2mm, positive rake angles of 3o, 5o and 8o and used to perform turning operations on mild carbon steel (CS1030) with surface roughness measured. The results showed that the strengthened tools generated the best surface finish for mild carbon steel among all three tools under consideration. The statistical analysis showed that surface finish, the model, cutting speed and feed rate are significant with their P-values < 0.0001 but the depth of cut, rake angle and tool have no significant impact on surface finish at 95% confidence level. This research will provide the machine tools shop with more durable SPTT and enhance reliability, quality, minimize downtimes and accidents in machining processes.

Novel Lignin-Functionalized Waterborne Epoxy Composite Coatings with Excellent Anti-Aging, UV Resistance, and Interfacial Anti-Corrosion Performance.

Developing high-performance lignin anti-corrosive waterborne epoxy (WEP) coatings is conducive to the advancement of environmentally friendly coatings and the value-added utilization of lignin. In this work, a functionalized biomass waterborne epoxy composite coating is prepared using quaternized sodium lignosulfonate (QLS) as a functional nanofiller for mild carbon steel protection. The results showed that QLS has excellent dispersion and interface compatibility within WEP, and its abundant phenolic hydroxyl, sulfonate, quaternary ammonium groups, and nanoparticle structure endowed the coating with excellent corrosion inhibition and superior barrier properties. The corrosion inhibition efficiency of 100mgL-1 QLS in carbon steel immersed in a 3.5wt% NaCl solution reached 95.76%. Furthermore, the coating maintained an impedance modulus of 2.29×106Ωcm2 (|Z|0.01Hz) after being immersed for 51 days in the high-salt system. In addition, QLS imparted UV-blocking properties and thermal-oxygen aging resistance to the coating, as evidenced by a |Z|0.01Hz of 1.04×107Ωcm2 after seven days of UV aging while still maintaining a similar magnitude as before aging. The green lignin/WEP functional coatings effectively withstand the challenging outdoor environment characterized by high salt concentration and intense UV radiation, thereby demonstrating promising prospects for application in metal protection.

Continuous Hydrothermal Carbonization of Olive Pomace and Orange Peels for the Production of Pellets as an Intermediate Energy Carrier

The ever-increasing volumes of food waste generated and the associated environmental issues require the development of new processing methods for these difficult waste streams. One of the technologies that can treat these waste streams directly is hydrothermal carbonization. In this work, olive pomace and orange peels were treated via a mild hydrothermal carbonization process (TORWASH®) in a continuous-flow pilot plant. For olive pomace, a solid yield of 46 wt% and a dry matter content of 58% for the solid press cakes were obtained during continuous operation for 18 days. For orange peels, the values were lower with 31 wt% solid yield and a 42% dry matter content during 28 days of continuous operation. These values corresponded fully with initial laboratory-scale batch experiments, showing the successful transformation from batch to continuous processing. The obtained hydrochar from both feedstocks showed an increase in higher heating value (HHV) and a significant reduction in ash content. Pellets produced from the solids met the requirements for industrial use, demonstrating a large increase in the deformation temperature and a significant reduction in the potassium and chlorine content compared to the original feedstock. These results indicate the excellent potential of these pellets for combustion applications.

Process evaluation of mild hydrothermal carbonization to convert wet biomass residue streams into intermediate bioenergy carriers

Hydrothermal carbonization (HTC) is a promising process for the upgrading of wet biomass residues. Models of HTC processes, in particular at continuous pilot-scale, are needed to move HTC from lab-scale to industrial scale. This study presents a process model for mild HTC, dewatering and conversion to intermediate energy carriers (bio-pellets and biogas for power and/or heat production) of three wet biomass residue streams: paper sludge, olive pomace and orange peels, based on lab- and pilot-scale experiments. In addition, the process energy efficiency and feedstock utilization of the HTC process is calculated and compared with conventional treatment options for the chosen residues, i.e., direct anaerobic digestion (olive pomace, orange peels) or combustion after conventional dewatering (paper sludge). The process model indicates that the HTC pilot-scale process is much more efficient in terms of feedstock utilization to produce heat and/or power than the reference scenarios. The process energy efficiency of the HTC process (pilot-scale) was calculated to be 26 %, 63 % and 40 % for paper sludge, olive pomace and orange peel feedstocks, respectively. For all feedstocks, both the solid and liquid-generated products are equally important for improving the overall process energy efficiency. This study demonstrates the potential benefits of HTC processes for upgrading wet biomass waste streams based on continuous pilot-scale data.

The inhibition efficiency of nitrated cottonseed oil on corrosion of mild carbon steel in CO2 medium

The inhibition efficiency of nitrated cottonseed oil on corrosion of mild carbon steel in CO2 medium

Enhancement effect of carvacrol on yeast inactivation by mild pressure carbon dioxide.

Saccharomyces cerevisiae is one of the common spoilage microorganisms in fruit juices. This paper investigated the influences of carvacrol on S. cerevisiae inactivation by mild pressure carbon dioxide (MPCO2). The results demonstrated that carvacrol synergistically enhanced the antifungal activity against S. cerevisiae of MPCO2. With the increase of carvacrol concentration (20-160µg/mL), CO2 pressure (1.5-3.5MPa), process temperature (20-40°C), and treatment time (15-60min), the inactivation effect of carvacrol combined with MPCO2 on S. cerevisiae was gradually increased and significantly stronger than either single treatment. In the presence of carvacrol, MPCO2 severely disordered the plasma membrane of S. cerevisiae, including the increase of membrane permeability, and the loss of membrane potential and integrity. MPCO2 and carvacrol in combination also aggravated the mitochondrial depolarization of S. cerevisiae and reduced intracellular ATP and protein content. This study suggests the potential of carvacrol and pressurized CO2 as an alternative technology for food pasteurization.

Experimental qualification of replaceable bolted links in dual eccentrically braced frames

AbstractThe performance of structures under severe seismic action is ensured by properly calibrated ductility, stiffness, and strength. The “plastic” members of ductile mild carbon steel (S235 to S355) dissipate the seismic energy, acting as “structural fuses”, while the “elastic” members must be provided with adequate overstrength, to have the capacity to carry the stresses corresponding to yielded and strain hardened plastic hinges. High strength steels, such as S460 to S690, might be used for these elastic members, providing them with the necessary overstrength, without enhancing the stiffness, as that could unbalance the structural system. Dual structural systems, as moment resisting frames (MRFs) combined with eccentrically braced frames (EBFs), can be equipped with replaceable mild carbon steel dissipative links acting as seismic fuses. The MRFs, possibly fabricated from high strength steel, remain elastic, being able to recover the initial position. The key problem in such systems is the design and calibration of the fuses, i.e. the replaceable bolted links, which should be carefully qualified by tests. The present paper reviews past research on bolted replaceable links and discusses the experimental qualification requirements.

Effect of copper content of AISI 1018 mild carbon steel on inhibition efficiency of imidazoline-based corrosion inhibitor in CO2-saturated brine

The effects of the copper content (varied from 0.054 to 0.158 wt%) of AISI 1018 mild carbon steel and pre-corrosion treatments on the inhibition efficiency (η) of an imidazoline-based corrosion inhibitor was investigated in CO2-saturated brine under dynamic flow conditions at 70 °C. An increase in the initial copper content of the steel results in a decrease in η and a decrease in the rate of inhibitor adsorption due to the formation of a porous cementite film enriched with iron carbide and zero-valent copper, leading to an increase in galvanic corrosion.

Experimental Investigation of Monotonic and Cyclic Behaviour of High-Performance Steels

As a new trend in modern structural design, the high-performance steels are increasingly used in steel structures, due to their superior mechanical properties, which could have decisive impact on the resistance and deformation capacity of structural components. High-performance steels include stainless and high-strength steels. The higher proof stress of the high-strength steels allows using thinner sections and material economy for those structural elements that do not experience stability problems. Austenitic stainless steel shows a series of advantages, including low maintenance costs and an excellent toughness at low temperatures. But the main characteristic which matters especially in seismic design, is the higher ductility, larger strain hardening and elongation at fracture in comparison with carbon steels. In this paper, the analysis of the behaviour of 1.4404 austenitic stainless steel and of S690 high-strength steel, in comparison with a reference S235 mild carbon steel is presented. This paper presents the assessment of the monotonic and cyclic performance of these steel grades, as well as the failure pattern, in order to assess the potential use in structural applications.