Process Steam Research Articles

Study on the effect of cyclic catalytic pyrolysis on sludge pyrolysis products

Pyrolysis technology has become a hot issue in the industry of harmless treatment of sludge in recent years. The present ex-situ catalysis process suffers from the defects of unidirectional flow of pyrolysis steam, easy to form coke buildup on the catalyst surface, and poor heating value of the output heavy tar, which is difficult to be reutilized. This paper designed a cyclic catalytic cracking by pyrolytic steam process to optimize the above defects: under the optimal experimental conditions (pyrolysis starting temperature was 500 ℃, final temperature was 800 ℃, iron-based carbon catalyst dosage was 4 g, and motor speed was 1050 r/min), this process generated more pyrolysis gas and light tar. The increase in pyrolysis temperature had the most significant effect on pyrolysis gas yield, the dosage of iron-based carbon catalyst had the most significant effect on pyrolysis gas composition, and the increase in motor speed had the most significant effect on tar cracking. The cyclic catalytic cracking by the pyrolytic steam process can increase the residence time of pyrolysis steam in the reaction unit and promote the secondary cracking, catalytic, and reforming effects of tar.

Technical and economic analysis of a multicarrier building energy hub concept with heating loads at different temperature levels

Integration of renewable and waste energy sources, decentralisation, electrification and energy storage, are key pillars of energy transition in the district heating sector. Such a strategy can be implemented at the building level using the multi-carrier energy hub concept, which has recently gained popularity. This paper presents a technical and financial feasibility study of a building-integrated multi-carrier energy hub concept. The case study is performed for an existing large medical centre, where demand occurs simultaneously for electricity, cold, and heat at different temperature levels, including hot process water and steam. The central idea is to replace the high-exergy steam with heat from the municipal district heating network. The concept also includes the integration of heating and cooling loads, heat storage and implementation of an on-site photovoltaic (PV) power plant. The key components of the proposed hub technological structure are high-temperature heat pumps. Five alternative structures of the system configuration are examined using an hour-by-hour annual simulation. The results reveal that the proposed multi-carrier energy hub is fully operational. The project is also profitable, which results mainly from significant energy savings compared to the existing heat supply system using high-pressure steam. However, the profitability strongly depends on the system configuration, and the choice of the best option is ambiguous. The system with heat storage reaches the highest net present value (NPV) while the one without the storage results in the highest internal rate of return (IRR) due to significantly lower capital expenditures (CAPEX). In all cases, the project leads to a considerable cumulative CO2 emissions reduction, which is at the level of 1351 up to 2961 tons annually depending on system configuration.

E-eye and FT-NIR combined with multivariate algorithms to rapidly evaluate the dynamic changes in the quality of Gastrodia elata during steaming process

Gastrodia elata (GE) is traditionally subjected to steaming, and steaming duration plays a crucially important role in determining GE quality. This study examined the variations in bioactive components during the steaming process and proposed the utilization of electronic eye and Fourier Transform near-infrared (FT-NIR) spectroscopy for quality assessment. The findings revealed that the levels of parishin E parishin B, parishin A, and gastrodin initially rose and subsequently declined, while 4-Hydroxybenzyl alcohol exhibited a rapid decrease followed by stabilization. With prolonged steaming, the brightness of GE decreased, while the red and yellow tones became more pronounced and the color saturation increased. FT-NIR divided the steaming process into three stages: 0 min (raw GE), 0–9 min (partially steamed GE), and 9–30 min (fully steamed GE), and the partial least squares regression models effectively predicted the levels of five components. Overall, this study provided valuable insights into quality control in food processing.

The impact of STEAM (STEM + arts) activities on learning outcomes in students with specific learning disabilities

AbstractThe aim of this research is to examine the effect of STEAM (STEM + Arts) education, which is an interdisciplinary approach that has been frequently used in developed countries in recent years, on the science course learning outcomes of students with specific learning disabilities. The model of the research was structured as a mixed design and was realized with an explanatory sequential design. In this context, the research took place in two separate interactive stages. In the first stage, a quantitative method was applied. In this section, a one‐group pretest–posttest pre‐experimental model was used. The research was carried out with 4 students who were studying in a state primary school in a province in the Southern Region of Anatolia and who were diagnosed with specific learning disabilities. As data collection tools, an academic achievement test and STEAM process rubric were used. Means and standard deviations were used in the analysis of the data collected from the pretest, posttest, persistence test and rubrics. In the qualitative section of the study, interviews were conducted with the participants in order to evaluate STEAM education in the light of the quantitative stage, and diaries were kept for the participants in the context of a more in‐depth and objective examination of the process. The data collected by qualitative data tools were subjected to content analysis and direct quotations were made from the opinions and diaries of the participants. As a result of the research, it was determined that the quantitative findings overlapped with the qualitative findings. It was observed that the STEAM activities increased the academic success of the participants, that their motivation was high, and that they were curious and eager for the activities. In addition, it was revealed that they made an effort to use the knowledge and experience they had gained from the STEAM activities in other courses.

Design and experimental investigation of a micro-scale bladeless-type steam turbine

There are plenty of sources of waste heat available in industry that are not frequently utilised, especially when it comes to small-scale installations and low-grade heat recovery. The reason is that traditional methods are not cost-effective or unsuitable for given operating conditions. However, recent technological progress has made reusing waste heat more feasible, not only for generating thermal, but also electrical power. This paper presents a new design of a micro-scale bladeless steam turbine suitable for combined heat and power (CHP) applications where low-grade waste heat is used, or as a replacement for pressure-reducing valves used to meet the demands of steam processing technologies in many industrial facilities. A 20 kW prototype of the turbine has been designed, built, and experimentally investigated to analyse its performance parameters. The results show that the turbine maximum isentropic efficiency was close to 30%, demonstrating that the turbine can compete with other concepts of bladeless-type turbines or with bladed designs in a power range below 100 kW where efficient solutions can hardly be found.

Analysis of the Characteristics of the Development of Web-Based Science Learning Media with the STEAM Approach

This research aims to analyze the characteristics of developing Web-Based Science Learning Media using the STEAM approach. This research is development research using the Research and Development (R&D) method with the Thiagarajan 4-D Model which consists of definition, design, development and implementation. Based on the validation results from experts and practitioners, the results are very suitable for use and have character because they have an attractive design, ease of use, and color selection that utilizes color psychology. The features provided are very responsive to learning needs, with an effective project-based STEAM learning flow using scaffolding. Users also have access to Google Data Studio to monitor the progress of each student's STEAM stages and processes. Discussion forums provide flexible interaction and feedback, while STEAM learning modules can be downloaded by teachers for more specific learning situations. The conclusion is that the website developed has unique and unique characteristics that combine color, a project-based STEAM learning flow with a real-time scaffolding system and presents features that make it easier for students to learn

Analisis Kadar Antosianin Uwi Ungu berdasarkan Metode Pengolahan Pengukusan, Perebusan dan Pemprestoan

Background : Anthocyanins are plant pigments that can be used as antioxidants. Generally orange, red, purple, blue. Purple yam is plant that contains a lot of anthocyanins. The processing process can cause damage to anthocyanins because anthocianins are compounds that are less stable. This research will examine the anthocyanin content in several cooking methods. The results of this study can used as a recommendation for the safest cooking methods. The results of this study can be used as a recommendation for the safest cooking method to minimize damage to purple yam. Methods: The method used in this study was experimental by deviding the purple yam in 3 treatments namely steaming, boiling and presto. Anthocyanin levels were measured after treatment and analyzed. Results : The highest anthocyanin content was found in purple yam with a steaming process, namely 117.99 ppm ± 1.75 SD. In boiling, the anthocyanin levels were 107.20 ppm ± 2.55 SD, and presto 106.13 ppm ±2.89 SD. Conclusion: The highest anthocyanin levels were obtained in the steaming process. Key word : Anthocyanin, Steaming, purple yam.

Ion transport membrane heat engine integration with autothermal reforming-based methanol production

This study focused on improving the energy demand of conventional large-scale natural gas to methanol flow sheet where even a small efficiency improvement has significant economics and carbon emissions benefits. A conventional flow sheet, case A, was based on best available literature information. A case B where the conventional cryogenic air separation unit (ASU) is replaced with the novel ion transport membrane (ITM) oxygen unit was developed. The ITM oxygen is also heat integrated into the autothermal reformer (ATR) process. A case C where the methanol synthesis process is configured into a gas turbine cycle was developed from further modifying case B. The flow sheets were constructed and modelled in Aspen Plus V10 and, heat and material balance results are reported. To our knowledge, the integration of ITM oxygen membranes into the ATR-based methanol process has not been assessed previously.Energy and exergy results are generated and analysed. It was found that is it possible to replace the cryogenic ASU with the ITM oxygen for oxygen production in the ATR process. There is enough process syngas heat available to provide the ITM oxygen unit heating requirement and to generate process steam feed to the ATR. Case A was found to consume only 12 % natural gas as utility fuel which is lower than typical SMR-based methanol processes. This reduced to about 5 % in case B and C. Power production improved by 47 % in case B and 68 % in case C compared to case A.A thermal efficiency definition suitable for combined process steam, power and oxygen production was proposed. This showed that integration of a high temperature gas power cycle enables combined steam (heat) and power configuration which has a higher efficiency compared to single cycles, such as the steam cycles. The overall plant exergy losses decreased by up to 21 %.

Curly Kale (Brassica oleracea var. Sabellica L.) Biofortified with 5,7-Diiodo-8-quinolinol: The Influence of Heat Treatment on Iodine Level, Macronutrient Composition and Antioxidant Content.

Many disorders are a result of an inadequate supply of macronutrients and micronutrients in the diet. One such element is iodine. This study used curly kale (Brassica oleracea var. Sabellica L.) biofortified with the 5,7-diiodo-8-quinolinol iodine compound. The effect of the heat treatment on the chemical composition of the curly kale was studied. In addition, iodine bioavailability was evaluated in in vivo studies. Our investigation showed that iodine loss depends on the type of heat treatment as well as on the variety of kale. Curly kale biofortified with iodoquinoline had significantly higher iodine levels after thermal processing (steaming, blanching, boiling) than the vegetable biofortified with KIO3. Generally, steaming was the best thermal processing method, as it contributed to the lowest iodine loss in curly kale. The red variety of kale, 'Redbor F1', showed a better iodine stability during the heat treatment than the green variety, 'Oldenbor F1'. The thermal treatment also significantly affected the dry matter content and the basic chemical composition of the tested varieties of the 5,7-diI-8-Q biofortified kale. The steaming process caused a significant increase in total carbohydrates, fiber, protein and crude fat content ('Oldenbor F1', 'Redbor F1'), and antioxidant activity ('Oldenbor F1'). On the other hand, boiling caused a significant decrease, while steaming caused a significant increase, in protein and dry matter content ('Oldenbor F1', 'Redbor F1'). The blanching process caused the smallest significant decrease in ash compared to the other thermal processes used ('Oldenbor F1'). A feeding experiment using Wistar rats showed that iodine from the 5,7-diI-8-Q biofortified kale has a higher bioavailability than that from the AIN-93G diet. A number of promising results have been obtained, which could form the basis for further research.

The Effect of Preparation Method on Anthocyanin Contents from Lpomoe Batatas (L.) Lam as Intelligent PH Indicator

Intelligent pH indicators have been gain interested in food industry as its acts as intelligent packaging where can be monitored and providing information and warning customer on the food condition in real time pH indicator. Calorimetric pH indicator used as indicator system in the packaging as in the most cases, pH changes can be detected when food deterioration occurs. However, the current pH indicator has lower colour changes and lower stability. In this research, new pH indicator was produced and have pronounced colour changes in wide range of pH that have higher stability to temperature and light from natural colorant sources. Two method of extract’s preparation was conducted to evaluate the effect of anthocyanin contents which is with or without steaming. The characterization was done by observing the physical appearance, total anthocyanin contents, UV-Vis analysis and colour response of anthocyanin to various PH solution. As the results, steaming of sweet potatoes preparation method was found able to produce dark purple colour with high value of total anthocyanin contents. Anthocyanin colour produced using steaming process results more intents colour at pH 1 to pH 13 compared to without steaming. These finding was supported with UV-Vis peak that showing different wavelength which corresponding to the various colour produced. The results obtained show the anthocyanin extracts is a promising component to be used as pH indicator since its stimuli responsive with the pH of the environments.

Pengembangan Kewirausahaan Ecoprint Berbasis Smart Steamer Machine Guna Meningkatkan Kualitas Produk dan Efisiensi

Ecoprint, a fabric printing and dyeing technique utilizing natural dyes with leaves, is currently experiencing a surge in demand and becoming a trend among fashion entrepreneurs and textile craftsmen. The unique patterns created from leaves distinguish ecoprint from traditional batik designs in the market, making it highly appealing. Apietz Craft, a Small and Medium Enterprise (SME), was established at the beginning of 2020 during the Covid-19 pandemic. Mostly operated by residents of Jl. Hasyim Ashari II, Sepanjang Village, Gondanglegi District, Malang Regency, the business faced challenges during the ecoprint fabric steaming process. The issues stemmed from the small size of the steaming pot and the lack of temperature control, leading to a decline in fabric quality. These obstacles hindered the ecoprint production process, resulting in suboptimal outcomes. In response to these challenges, this PKM program proposes a solution by introducing a technology transfer initiative. A smart steamer machine will be implemented, designed to accommodate a larger capacity and capable of monitoring temperature within the machine. This advancement aims to enhance production quality and improve production efficiency. The initiative is expected to address the current issues faced by our partner, enabling them to achieve optimal ecoprint fabric production.
 Keywords: Smart Steamer Machine, Ecoprint, Development Entrepreneurship

Моdern heat and steam supply systems of industrial enterprises using deep utilization of the technological steam energy potential

Steam supply systems of industrial enterprises, as a type of heat supply system, are a large consumer of primary energy in national energy balances. In turn, due to the specificity of thermodynamic steam processes, steam supply systems of industrial enterprises in practice have significant unused potential of secondary energy resources (SEP). Modern steam supply systems should be built exclusively when evaluating their exergetic efficiency, which will make it possible to evaluate the effectiveness of such systems grossly in all elements of the life cycle of the project: energy, economic, ecological and even social. The article shows modernized thermal schemes of steam supply systems, for which it is possible to achieve additional electrical power at the level of 135-250 kW/(kg/s) when devices with a relative internal efficiency of up to 60-70 % are operating. In combination with an increase in the percentage of condensate return and the utilization of secondary energy resources (SRP), the increase in energy efficiency of the system is 2-4 %, and the absolute value of exergetic efficiency is 16-22 %, taking into account the exergetic efficiency of the boiler unit. Low-potential "tail" consumers: the heating system, the hot water supply system - increase the exergy efficiency of the steam supply system of an industrial enterprise by 0.2-0.6 % in the case of joining on the steam side of secondary boiling. Any processes of generating electrical energy are associated with obtaining a significant amount of thermal energy, and must be accompanied by its utilization; enterprises that use steam as an energy carrier (the same applies to energy enterprises such as thermal power plants and nuclear power plants) for the deep utilization of hydroelectric power plants must have thermal energy consumers in their composition, which can act as communal household consumers (if they exist), as well as new technological consumers of thermal energy.

Evaluation of the effects of thermal processing on antioxidant activity and digestibility of green tea noodles: Based on polyphenol stability and starch structure

The health benefits of green tea noodles (GTN) are strongly influenced by polyphenols' thermal stability and starch's thermal denaturation. This study aimed to comprehensively assess the influence of different thermal processing methods (i.e., steaming, boiling, roasting and frying) on the antioxidant activity and in vitro starch digestibility of GTN. As a result of thermal processing, the polyphenol content and antioxidant activity decreased, with correlation analysis showing a significant increase in polyphenol retention as antioxidant activity increased. GTN showed the greatest polyphenol stability during steaming compared with other thermal processing. Under the optimal cooking time, steaming and frying processing methods remarkably delayed the starch hydrolysis rate and reduced the estimated glycemic index (eGI). Further analysis proved that polyphenol content and retention rate, starch structure and the state of starch in the gluten network directly affected the in vitro starch digestion properties of GTN. Thus, steam processing will be an effective method for maximizing the functional properties of GTN from a healthy perspective.

Identification of raffinose family oligosaccharides in processed Rehmannia glutinosa Libosch using matrix-assisted laser desorption/ionization mass spectrometry image combined with machine learning.

Currently, research on oligosaccharides primarily focuses on the physiological activity and function, with a few studies elaborating on the spatial distribution characterization and variation in the processing of Rehmannia glutinosa Libosch. Thus, imaging the spatial distributions and dynamic changes in oligosaccharides during the steaming process is significant for characterizing the metabolic networks of R. glutinosa. It will be beneficial to characterize the impact of steaming on the active ingredients and distribution patterns in different parts of the plant. A highly sensitive matrix-assisted laser desorption/ionization mass spectrometry image (MALDI-MSI) method was used to visualize the spatial distribution of oligosaccharides in processed R. glutinosa. Furthermore, machine learning was used to distinguish the processed R. glutinosa samples obtained under different steaming conditions. Imaging results showed that the oligosaccharides in the fresh R. glutinosa were mainly distributed in the cortex and xylem. As steaming progressed, the tetra- and pentasaccharides were hydrolyzed and diffused gradually into the tissue section. MALDI-MS profiling combined with machine learning was used to identify the processed R. glutinosa samples accurately at different steaming intervals. Eight algorithms were used to build classification machine learning models, which were evaluated for accuracy, precision, recall, and F1 score. The linear discriminant analysis and random forest models performed the best, with prediction accuracies of 0.98 and 0.97, respectively, and thus can be considered for identifying the steaming durations of R. glutinosa. MALDI-MSI combined with machine learning can be used to visualize the distribution of oligosaccharides and identify the processed samples after steaming for different durations. This can enhance our understanding of the metabolic changes that occur during the steaming process of R. glutinosa; meanwhile, it is expected to provide a theoretical reference for the standardization and modernization of processing in the field of medicinal plants.

An innovative processing driven efficient transformation of rare ginsenosides enhances anti-platelet aggregation potency of notoginseng by integrated analyses of processing-(chemical) profiling-pharmacodynamics

Ethnopharmacological relevancePanax notoginseng (Burk.) F. H. Chen, a valuable Chinese herb medicine, shows a characteristic bi-directional regulation of hemostasis and activating blood circulation with ginsenosides as the predominant bioactive compounds and is a typical representative of “processing triggered heteropotency”. Aim of the studyProcessing triggered heteropotency, one of the unique theories and practices in traditional Chinese medicine, refers to that the processing will lead to change in physical and chemical properties, and eventually disparate efficacy of the crude drugs, yet the optimum process and underlying mechanism remains unclear. In this study, using Panax notoginseng (PN) as a representative sample, a processing-(chemical) profiling-pharmacodynamics (3-P) relationship was proposed to investigate the processing mechanism of PN. Materials and methodsFirstly, a temperature programmed steaming process was designed to evaluate the steaming triggered chemical transformation of triterpene saponins and the corresponding enhancement in anti-platelet aggregation activity. The steaming process was programed from the conventional 100 °C–150 °C in a time course of 0–12 h, aiming to achieve the maximized conversion of rare ginsenosides (RGs), and dynamic profile of ginsenosides were constructed by a UPLC-Q-TOF-MS/MS analysis. Then, a processing-(chemical) profiling-pharmacodynamics (3-P) relationship was assessed by using the grey relational analysis (GRA) and orthogonal projections to latent structures (OPLS), and validated by bioactive fraction of 140 °C steamed PN. Subsequently, the P2Y12-ligand binding affinity of potential candidates was analyzed by molecular docking. Finally, the dynamic changes of ginsenosides during steaming of SPN were quantitatively detected by UPLC-QQQ-MS/MS. ResultsA total of 48 differential ginsenosides were characterized and monitored including the primary and secondarily transformed saponins. The higher temperature steaming especially at 140 °C induces not only the predominant production of the RGs, but also the stronger anti-platelet aggregation activity. The 3-P relationship showed the fraction (3) of 140 °C steamed PN rich in RGs exhibits the most predominant efficacy, in which, a series of RGs including ginsenosides Rg5, Rk1, 20(S/R)-Rg3 were proven to be potent components. Molecular docking analysis suggested that ginsenosides Rg5 and Rk1 showed more strong interaction with the platelet P2Y12 receptor. Quantitative analysis found 140 °C-2h PN possessed highest contents of Rk1 and Rg5 and total RGs. ConclusionsThe integrated 3-P strategy uncovered the promising ginsenosides with anti-platelet effect, thereby revealing the material basis of PN steaming, which could provide a new enlightenment for the investigation of processing mechanism of traditional Chinese medicines.

Potential development and utilization of sweet potato flour as a raw material for the food industry

Sweet potato (Ipomoea batatas) is one type of tuber that has an important role in food diversification programs. Each 100g of sweet potato contains 27.9 g of carbohydrates, 7000 SI of vitamin A, 30 mg of vitamin C, 30 mg of mineral Ca and an energy value of 123 calories. Its carbohydrate content ranges from 64.83 to 66.90% which is a potential energy source to meet basic food needs other than rice. Sweet potato is considered as a raw material for the food industry, because it has good nutritional content, short plant life, and high production. Its vitamin B6 and folic acid is needed to optimize brain work, rich in fiber and complex carbohydrates but low in calories which is very good for diabetics. However, the soft texture of sweet potatoes and the high of its water content make sweet potatoes easy to damage due to mechanical influences. Processing into flour is one of the efforts to preserve sweet potatoes and increase their usefulness. Ingredients composition, drying method, use of chemicals, and steaming process are factors that can affect flour quality, especially its color and functional characteristics. Drying methods that can be used are spray drying, drum drying and oven dryer. The aim of this review is to explore the opportunities and potential of sweet potato flour (SPF) as an industrial raw material for processed food industries in Indonesia. The review method used is the reference collection method, which is taken from several research results related to SPF and its application to food products such as beverages, fructose syrup, noodles, flakes, cookies, ice cream, yogurt, jams, dyes, and others. Through the preservation of sweet potato into flour and its use as industrial raw material, it is hoped that it can increase the diversity of functional foods needed by the Indonesian community.

Penentuan Kadar Albumin Ikan Gabus (Channa striata) dengan Metode Biuret setelah Dikukus dan Dipepes

Snakehead fish (Channa striata) is a type of freshwater fish that contains high levels of protein albumin. The research was conducted to determine the albumin content in snakehead fish after the cooking process, both steamed and wrapped. The research was conducted using a completely randomized design with a factorial pattern, the first factor was the cooking method (steamed and wrapped) and the second was cooking time (10, 15, 20, and 20 minutes). Determination of protein albumin levels in snakehead fish after processing using the Biuret method. The steaming process for 15 minutes resulted in protein content in the snakehead fish of 0.76%, while the protein albumin that was lost was 19.28%. The wrapped method for 20 minutes has a remaining protein content of 0.59%, while the missing protein is 38.78%. The method of processing snakehead fish by steaming is better than the wrapping process.

Modeling Delamination of Electrodes of Solid Oxide Electrolyzers with Fuel Electrode as a Support

Solid oxide electrolyzers (SOE) are the most efficient yet not fully mature devices for electrochemical production of hydrogen. These devices offer a great advantage in applications which make it possible to utilize process heat or steam to feed SOE for direct conversion of steam instead of water. However, the technology is prone to a degradation, as it combines advanced materials, requires dedicated fabrication techniques and it operates at elevated temperature, typically above 650ºC. One of the biggest challenges is the mitigation of degradation of solid oxide electrolyzers due to the delamination of the electrode. Several measures can be proposed to limit the process, however full elimination of this type of degradation is not yet possible. The good understanding of the mechanisms and consecutive steps which lead to deterioration of the interface between the electrolyte and air electrode of SOE is based on thorough experimental studies supported by the numerical modeling.In the study we present a delamination model, which can be used to identify the safe operating envelope of SOEs with a given structure and material composition. The mechanisms behind degradation through delamination are discussed with respect to the chemical and electrochemical potentials. This is complement by the discussion of criteria for the formation and propagation of cracks, taking into account the oxygen potential at the electrolyte-electrode interface. Moreover, the microstructural modifications of the electrodes, e.g. increase of its porosity, are discussed as one of the potential measures to substantially reduce the risk of delamination under design point and off-design operation of SOEs. The methodology of manipulating the porosity of the electrode by varying the content and type of pore forming agents was proposed in order to adjust the parameters of electrodes to the required microstructure. Results of the experimental characterization of cells fabricated in such a way are presented, and the guidelines for fine-tuning the microstructure are discussed with respect to the degradation mechanisms.

Nature-inspired Apatite Production: Steam Processing of Calcium Carbonate and Tricalcium Phosphate Nanosized Powder Blends

Green production of materials is crucial to protect the environment. In this article, a low-temperature steam synthesis strategy for apatite production is shown for limiting chemical pollution and enabling the control of crystallinity. Steam processing produced apatite from calcium carbonate and tricalcium phosphate nanosized powders. Interdiffusion between amorphous precursors gave hydroxyapatite accompanied by calcium-deficient hydroxyapatite. This study unfolds the potential of hydrothermal processing in steam as a synthesis strategy that has been forgotten since the 1950s showing where two solid nanosized powders react to form a new product without creating waste, thereby emulating the clean processing route found in nature. This research reopens the consideration of steam processing for more chemically diverse alternatives and processing of various calcium resources readily available in nature, such as eggshell waste, for greener production. Furthermore, it presents a rarely found combination of apatite forms.

Surface Hardness and Abrasion Threshold of Chemically Strengthened Soda-Lime Silicate Glasses After Steam Processing

Chemical strengthening by diffusive ion exchange (IOX) is a common method to improve the mechanical performance of glass products. However, the process of ion-stuffing is often associated with an increase of surface hardness and a decrease of the resistance to abrasive wear during scratching, even when the thickness of the exchanged layer is low. Autoclave steam-treatment presents a way to compensate the enhanced surface brittleness accompanying IOX. It causes a notable shift in the load threshold for microabrasion to more abrasion-resistant glasses. Subject to the specific processing parameters, the softening effect is constrained to a surface layer of less than 500 nm in thickness; therefore, the overall compressive stress profile is not affected and the advantages of IOX strengthening are retained. In turn, ion-stuffing by IOX counteracts severe autoclave corrosion of soda-lime silicate glasses, making them suitable for a combination of both processes.