Drying Process Research Articles

Dry cleaning process and mechanism of gas–solid fluidized bed for waste film plastics

Dry cleaning process and mechanism of gas–solid fluidized bed for waste film plastics

Coating of Hemp Fibres with Hydrophobic Compounds Extracted from Pine Bark

Applying coatings of paraffins and other synthetic waxes is a common approach to impart hydrophobic properties to fibres and thus control their surface characteristics. Replacing these fossil-based products with alternatives derived from renewable resources can contribute to humankind’s transition to a sustainable bioeconomy. This study presents the coating of hemp fibres with waxes extracted from pine bark as an exemplar application. Two bio-based emulsifiers were used to prepare wax emulsions suitable for a dry blending process. The coatings on the fibres were characterised, quantified, and visualised using a combination of spectroscopic and microscopic techniques. Confocal fluorescence microscopy was an excellent tool to investigate the spatial distribution of the pine bark waxes on the fibre surfaces. While successful deposition was demonstrated for all tested formulations, coating homogeneity varied for different emulsifiers. Compounding the hemp fibres with a bio-based polyester resulted in the substantial improvement of the mechanical behaviour. However, the presence of a wax coating on the fibres did not lead to a significant change in mechanical properties compared to the controls with uncoated fibres. Optimising the composite chemistry or adjusting the processing conditions might improve the compatibility of the hemp fibres with the matrix material, resulting in enhanced mechanical performance.

Qualitative and quantitative analysis of major components in Abelmoschus manihot flowers treated with different drying methods using UHPLC Q-exactive MS and HPLC-PDA

The flowers of Abelmoschus manihot (L.) Medic are commonly used in clinical practice in China to cure forms of chronic kidney disease. Despite a long history of traditional use, the flowers obtained by different drying technologies have never been fully chemically characterized, and the ranges of constituents between different drying methods have not been comprehensively reported. To establish a quality control and chemical characterization method, a total of 14 batches of samples corresponding to 14 postharvest treatments were studied. Seven flavonoids were quantified using a HPLC-PDA method. The method was validated in terms of linearity (r > 0.999), precision (intra- and inter-day: 0.7–1.4 %), accuracy (99.90–100.7 %), detection limit (0.34–0.46 µg/mL) and quantification limit (1.15–1.52 µg/mL). The contents of total flavonoids in manihot flowers were as follows in descending order: Infrared Drying (50.96 mg/g) > Microwave Drying (41.84 mg/g) ≈ Hot-air Drying (39.58 mg/g) ≈ Fresh (39.35 mg/g) ≈ Primary Drying (38.95 mg/g). Principal component analysis showed that samples processed with Fresh, Primary Drying, and the investigated three modern drying methods were well classified into three domains, indicating an important difference between drying methods. For the purpose of saving the flavonoids contents, infrared drying under 80–100 °C would be most acceptable. Furthermore, using UHPLC Q-Exactive Orbitrap MS data with targeted and non-targeted approaches, 28 compounds were identified in Abelmoschus manihot samples. Flavonoids were the main group of compounds found in Abelmoschus manihot flowers. The study could provide the scientific evidence for the selection and optimization of appropriate drying method for manihot flowers, and also provide the reference for the formation of generic primary drying processing technology for medicinal flowers containing flavonoids.

Drying of avocado peels using carbonation-ultrasonication as pretreatment: energy consumption, antioxidant capacity and rheological properties

Fruit processing by-products, especially peels are underused and mostly discarded as waste. The aim of this study was to assess the effect of ultrasonication (US) combined with carbonation (CUS) on the convective drying process of avocado peels at different temperatures, adding value to this waste. For this, the avocado peels were treated with dry ice for 15 min and subjected to US (400W/10 min, 30°C) before convective air drying (50-70°C). The energy consumption, antioxidant capacity, water adsorption isotherms, rehydration rate, and dynamic rheology of dried avocado peels pretreated by CUS were compared with a control process (without pretreatment) and only US pretreatment. The combined treatment (CUS70) resulted in a 2.6-fold reduction in drying time and a 2.3-fold decrease in energy consumption, with CO2 preserving bioactive compounds and antioxidant capacity after the drying process. Differences were also observed in the rehydration capacity of the samples (CUS), with an increased water absorption capacity, along with a reduction in the viscoelastic properties of the peels. The results present new perspectives for the application of CUS in the food industry, paving the way for the development of creative, innovative, and simple approaches for the management and recycling of agri-food waste, with the potential to extend this knowledge to new food matrices.

Heat pump drying kinetics modeling and prediction for Lentinus edodes based on orthogonal experimental

To accurately understand the moisture variation and drying characteristics of Lentinus edodes (L. edodes) during the drying process, the kinetics model of L. edodes with a wider application range was investigated. First, the heat pump drying kinetics model for L. edodes was fitted, verified and extended based on the orthogonal experimental data. Then, the expression of moisture ratio of L. edodes with respect to drying time, air supply temperature (AST), loading density (LD) and circulating air volume (CAV) was proposed, and interaction effects of the three key parameters on the drying time were studied based on the prediction model. The findings indicated a substantial agreement between the predicted and experimental values. The drying time could be shortened by increasing the air supply temperature and the circulating air volume or decreasing the loading density. Among these three factors, the AST had the greatest impact on drying time, followed by CAV and LD. For every 48 g/m2 reduction in LD and 11.3 m3/h increase in CAV, the drying time could be reduced by 10.5 to 29.9 minutes. Similarly, increasing the AST by 1 °C and the CAV by 11.3 m3/h could decrease the drying time by 13.7 to 100.6 minutes. The research results are helpful to optimize the drying process, improve the drying efficiency, and provide guidance and references for practical production of L. edodes HPD.

Effect of different drying temperature settings on the color characteristics of Tencha

Color is critical factor in the commercialization of Matcha. In this study, sensory evaluation, color difference analysis, as well as targeted and non-targeted analyses were employed to investigate the impact of different drying temperature settings on the color characteristics of Tencha. The findings revealed that compared to a single drying temperature setting, a two-stage or multi-stage drying process more effectively preserved the color quality of Tencha. Specifically, a setting involving an initial period of high-temperature drying followed by low-temperature drying (samples T_6, T_7, T_10, and T_13) resulted in superior tea color quality, characterized by higher chlorophyll content and lower levels of lutein and β-carotene. Chemometric analysis identified chlorophylls and their derivatives (chlorophyll a/b, pheophytin a/b, pyropheophytin a/b) as the key factors influencing Tencha's color. These results can provide valuable insights for optimizing tea processing methods to enhance quality.

Exploring synthesis techniques for an imidazole-based one-component epoxy latent curing agent: Chemical capping and mechano-chemical capsuling

The increasing demand for one-component epoxy is driven by its eco-friendliness, convenience, and cost-effectiveness, underscoring the importance of developing latent curing agents that trigger reactions under specific conditions. This study introduces an imidazole-based latent curing agent (ICM-SU) characterized by superior storage stability and low-temperature curing capabilities, achieved through dual protections of chemical capping and mechano-chemical capsuling. The process commences with the synthesis of isophorone diisocyanate capped 2-methylimidazole (ICM), wherein the reactivity of 2-methylimidazole (2MI) is controlled via the inductive effect of isophorone diisocyanate, achieved through chemical capping. Subsequently, ICM-SU is produced by uniformly coating it with silica nanoparticles and a urea shell through mechano-fusion system’s dry processing for mechano-chemical capsuling, effectively isolating it from contact with epoxy. The curing mechanism and chemical structure of ICM-SU are identified in four stages: de-capping, de-shelling, formation of epoxy-imidazole adducts, and chain growth. Notably, the melting point of the urea shell (122 °C) closely matches the curing onset temperature, suggesting that the exposure of epoxy to restored 2MI initiates the curing process. As a result, ICM-SU demonstrates significantly enhances storage stability at 20 °C for over 42 days, a stark improvement over 2MI, which solidifies within 8 h. Moreover, specimens cured with ICM-SU exhibits a 32 % increase in tensile strength and a 25 % improvement in Young’s modulus compared to those cured with 2MI, attributed to the reinforcing filler effect of silica nanoparticles.

Mechanical and Durability Properties of Rubberized Sulfur Concrete Using Waste Tire Crumb Rubber

The use of rubber crumbs provides a viable solution for alleviating the disposal problem of waste tires. In this study, rubberized sulfur concrete (RSC) was researched to investigate the optimal mixture proportion and to improve the mixing process in terms of compressive strength and durability performance. For the mixture of the RSC, sand, rubber particles, and micro-filler were adopted as aggregates and sulfur was used for the binding material. Moreover, two mixing processes were applied: the dry mixing process and the wet mixing process. Based on the test results, the increment of rubber particles in the mixture led to a decrease in the compressive strength for both the dry and wet mixing processes. To minimize the voids between the sand and rubber particles, the micro-filler was used at 5% of the total volume. The amount of sulfur varied slightly depending on the mixing process: 30% sulfur for the dry mixing process and 34% sulfur for the wet mixing process, respectively. Consequently, compared to the dry mixing process, the wet mixing process increased the bonding force between sulfur and rubber powder due to the simultaneous heating and combining. In toughness, the wet mixing process demonstrates a 40% higher energy absorption capability compared to the dry mixing process. For the durability performance of the RSC, the mixture with 20% rubber particles produced using the wet mixing process exhibited better corrosion and freeze–thaw resistance.

Evaluation of Greenhouse Gas Emission Assessment Resulting from Processing Municipal Organic Waste into Bahan Bakar Jumputan Padat for Co-firing in Power Plants; Case Study: Bagendung Landfill Cilegon City

One type of biomass that can be used as fuel for co-firing in power plants is Bahan Bakar Jumputan Padat (BBJP)/Solid Waste Fuel. BBJP is a non-hazardous waste derivative that cannot be recycled. The production process of BBJP is strictly regulated by the Indonesian national standard (SNI) 8966:2021. The definition, characteristics and specifications of BBJP are much closer to Solid Recovered Fuel (SRF) than Refuse Derived Fuel (RDF). The utilization of BBJP reflects the dedication to reducing waste in landfills with a circular economy concept approach as well as the transition of the energy mix in Indonesia. To the present day, the production capacity of BBJP at Bagendung landfill in Cilegon City, Banten Province, has successfully produced 30 tons/day of organic municipal waste with an average BBJP product yield ranging between 11-15 tons/day. This research is intended to assess the Greenhouse Gas emissions (GHG) generated from the processing of municipal waste into BBJP. There are three main processes that produce GHG emissions, namely during bio drying processing, the use of machinery that produces emissions from electricity and the transportation process that produces combustion emissions in diesel fuel. As a result, direct GHG emissions arising from all waste processing activities into BBJP consist of 10 pollutants, namely CH4, N2O, CO, NH3, CO2, NOX, SO2, NVMOC, PM2.5 and ID(1,2,3,c,d)P. CO2 emission is the largest pollutant, accounting for 96.70% of the entire BBJP process.

Simulation Analysis of 3-D Airflow and Temperature Uniformity of Paddy in a Laboratory Drying Oven

This study analyzed the effects of airflow characteristics on the temperature distribution and drying uniformity of paddy during convective drying. Simulations of the drying process with varying airflow inlet and outlet positions were conducted using COMSOL Multiphysics 6.1 software. The determination coefficient (R2) between the simulated data and experimental values of Sample1 (S1), Sample2 (S2), and Sample3 (S3) was calculated, and its average values were 0.964, 0.963, 0.963, and 0.967, respectively. This study demonstrates that the airflow direction and outlet location have a significant impact on the temperature uniformity of the paddy. The vortex structure generated by the obstruction of the sidewalls and paddy influences both the airflow and temperature distribution within the drying chamber. When the outlet was on the left side and the inlet airflow was in a vertical orientation (VO), the temperature distribution of the paddy exhibited higher temperatures in the edge regions and lower temperatures in the center, with a maximum temperature difference of around 16 °C. The time required for the temperature to reach equilibrium with the outlet positioned on the left was 28.6% shorter than with the outlets positioned in the center or on both sides. Moreover, the temperature uniformity of the three paddy samples was better under this condition. The developed model accurately reflected the paddy drying process. It could also be used to analyze the optimal heating uniformity, providing a technical basis for the design of grain dryers.

Tribological and mechanical endowments of polyoxymethylene by liquid‐phase exfoliated graphene nanofiller

AbstractIn this study, a viable route to the development of a high‐performance polyoxymethylene (POM)‐based nanocomposite is proposed to overcome tribomechanical‐related issues in high‐precision sliding parts. Prior to melt‐blending, graphene nanoplatelet (GNP) filler was processed via a series of liquid‐phase exfoliation and surface modification with 3‐aminopropyltriethoxysilane. Results indicate that GNP is successfully exfoliated with minimum defect ratio and improves interfacial bonding within the matrix. Uniform dispersion and stable load‐transfer capability of POM/GNP with 0.5 wt% loading significantly enhanced flexural, tensile and impact strength by overall 26.4%, in contrast to unfilled POM. Dry friction tests against a steel ball also showed the lowest reduction in friction coefficient and wear rate by 22% and 40.6%, respectively, at the same amount of GNP loading due to the large specific surface coverage and lubricious transfer film chelation onto the steel counterface. Furthermore, dissipated energy accumulation by friction work was calculated in the sliding interfaces based on friction force–displacement hysteresis loop where the POM/GNP 0.5 wt% wear surface consumed ca 21.7% less energy in a dry frictional shearing process compared to neat POM. However, lack or excess loading of processed GNP exhibited insufficient or poor matrix–filler adhesion and led to deterioration of the composite properties due to particle agglomeration which can cause stress concentration and serve as a failure site. The adoption of the proposed methodology would demonstrate excellent material characteristics in thin‐walled precision parts where both mechanical and tribological performances are the primary concern. © 2024 Society of Chemical Industry.

Energy, exergy, exergo-economic and exergo-environmental analysis of waste heat-based convective dryer

Food drying is a widely used method of food preservation worldwide, and the utilization of waste heat from exhaust flue gas presents a significant opportunity to reduce the energy consumption of industrial drying processes. This study thoroughly examines the energy and exergy efficiency, sustainability indicators, and various exergo-environmental and exergo-economic parameters to assess the performance of a waste heat-based convective dryer (WHCD). The study found that drying at 70 °C performed the best (among 50 °C, 60 °C and 70 °C) for the overall drying process, with a maximum overall exergetic efficiency of 4.89 %. The results of exergo-economic analysis revealed that the drying chamber exhibited the highest exergy destruction cost at US$0.01193 per hour, and it was determined that improving the drying chamber was of paramount importance. An exergo-environmental assessment indicates that the proposed dryer effectively mitigates 14.15 tons of CO2 over a 20-year lifespan. Sensitivity analysis of the proposed system reveals that the energy efficiency is more sensitive to the food drying temperature than the exergy efficiency. A 33 % increase in drying temperature increases the exergy efficiency by 19.37 % while reducing the energy efficiency by 37.54 %. Hence, adopting the proposed system in industrial settings could significantly enhance energy-efficient and sustainable food drying processes.

Optimizing dry milling of stir-cast and heat-treated AZ80 magnesium alloy using multiple criteria optimization technique: an experimental study.

The primary aspects of this research are to evaluate surface roughness, cutting force, and material removal rate and optimize it with dry milling process parameters for heat-treated and stir-cast AZ80 magnesium alloy. Multiple methodologies are utilized in the research, which includes the Integration of design of experiments-response surface methodology for experimental design with the technique for order of preference by similarity to ideal solution for multi-criteria optimization. In order to evaluate the effect of process parameters on the response, the experimental design manipulates the depth of cut, feed rate, and cutting speed in a systematic manner. An evaluation of the machined surface's quality is conducted via surface roughness measurements. Likewise, insights into the forces exerted during milling can be obtained through continuous monitoring of cutting forces. The calculation of material removal rate is predicated on weight reduction. The interaction between the depth of cut and feed rate has a significant impact on the critical-to-quality characteristics of the alloy, which has contribution percentage greater than 25%. This finding validates that despite the heat-treated alloy having a similar composition to the as-cast alloy (where the closeness coefficient is 0.9843), the optimal process parameters of the former are not applicable to the latter. Nevertheless, the technique used to prepare the specimen has no bearing on the material removal rate, which is a process parameter-specific effect.

INOVASI PRODUKSI PACKAGING MANAJEMEN USAHA DAN DIGITAL MARKETING BERBASIS ENVIRONMENTAL SUSTAINABILITY BAGI PETANI GARAM JONO

The national need for salt increases every year along with population growth. Jono Village, Tawangharjo District, Grobogan, Central Java is known as a center for salt production. The source of the earth's spring water in the form of belik, is used by residents to make salt. Although far from the sea, the water from the source tastes salty and warm. Salt production has been around for hundreds of years. In 1960, there were hundreds of salt farmers, now there are dozens left. This requires attention from various parties. The purpose of the community service program in the Jono Village Salt Farmer Group is to provide solutions based on situational analysis of the needs, challenges, or problems that exist in the community and carry out activities that can empower the community. Specifically, with service with salt group partners, it is hoped that it can increase the production of salt, and provide more modern packaging for the salt product. This service can improve the marketing of the salt, it can be sold in modern stores, but it can only enter traditional markets. The results of the study show that Jono salt is tastier and tastier. In terms of belik water before being made into salt, the water feels warm and contains lots of minerals so it is good for health, both for skin diseases and other diseases. The method of implementing the service is carried out by conducting program socialization by the service team to Jono's salt farmer partners, with stages of training and mentoring of the service program. The training and mentoring of the program include increasing salt production with the tunnel method, packaging training using machine packaging technology, and business management mentoring and marketing mentoring. Furthermore, the application of technology in the form of a tunnel method for the salt drying process, packaging technology using a salt packaging machine, mentoring and evaluation as well as program sustainability.

Mass‐Producible Self‐Powered Solar‐Blind Ultraviolet Photodetector Based on Graphene/β‐Ga2O3 Heterojunction Processed by Wet Transfer

AbstractGraphene electrodes draw considerable attention in solar‐blind ultraviolet (SBUV) detection owing to their unique features including high ultraviolet (UV) transparency and superior intrinsic carrier mobilities. However, their adoption comes with challenges, as the most commonly used preparation technique, i.e., the dry transfer process, is challenging to achieve mass production. In this work, graphene/β‐Ga2O3 heterojunction photodetectors processed by wet transfer are reported. Benefiting from the UV‐transparent electrode and heterojunction, both the responsivity and response speed are improved. The characteristic of the graphene/β‐Ga2O3 interface is analyzed by the current–voltage (I–V) and capacitance–voltage (C–V) curves, featuring a high‐quality junction. Operated at zero bias, the photodetector exhibits a low dark current of less than 1 pA and a high response speed of less than 1 ms. An excellent UV‐C/visible rejection ratio is also achieved. Importantly, the photodetector performs excellent reproducibility and performance stability. This results provide a new perspective for the mass production of graphene/Ga2O3 integrated devices, enabling high‐performance Ga2O3 photodetector arrays.

Low-temperature Deposited Highly Sensitive Integrated All-Solid Electrodes for Electrochemical pH Detection

This article describes the process of fabricating an integrated all-solid electrode (IASE) by integrating thin films of titanium dioxide (TiO<i>2</i>) and silver/silver chloride (Ag/AgCl) onto an indium tin oxide (ITO) substrate. The fabrication of a pH sensing electrode (SE) involved utilizing a spin-coated thin film composed of TiO<i>2</i>. Thermally produced thin films of Ag/AgCl were used to develop solid reference electrodes (RE). The present work examined the impact of the drying process on the pH sensitivity and linearity of the low-temperature deposited IASE. The drying procedure was carried out within a temperature range from room temperature to 100°C. The investigation involved the examination of crystallinity, surface morphology, and thin film composition through the utilization of field effect scanning electron microscopy (FESEM), X-ray diffraction (XRD), and energy-dispersive X-ray (EDX) methods. In addition, a comparison was made between the pH sensing performance of the IASE and a commercially available Ag/AgCl RE. The findings of this research demonstrate that the IASE sample, which underwent a drying process at a temperature of 100°C, exhibited remarkable sensitivity and linearity values of 66.7 mV/pH and 0.9827, separately, when compared to the commercially available RE.

Comparative study on the difference of saponins and nutrients in Panax notoginseng powder dried by new rapid drying technique and traditional hot air.

Panax notoginseng (Burk.) F. H. Chen (PN), commonly known as PN, is a nutritious natural food with a long history of consumption and has traditionally been used for dietary purposes in the form of dried processed products. Currently, developed a dry processing at short time and room temperature (DRST), which is characterized by high efficiency and low cost. However, there are few studies on the impact of DSRT. In this study, the effects of conventional hot air drying (DHA) and the innovative drying technology DSRT on the key components of PN were evaluated for the first time. The results showed that DRST could obtain processed PN products with smaller particle sizes and that DRST-treated PN could increase the content of five saponins by 1.38% for Ginsenoside Rg1, 0.1% for Ginsenoside Re, 0.83% for Ginsenoside Rb1, 0.16% for Ginsenoside Rd, and 0.36% for PN saponin R1, relative to the content of five saponins that could be increased by conventional DHA. The metabolome results yielded a total of 1401 metabolites identified and analyzed, and 201 metabolites showed significant differences between the two techniques, which were expressed as amino acids, flavonoids, and other nutrient-active components. The results of this study indicate that the PN products produced by DRST technology have higher nutritional quality compared to traditional processing. This study provides support in the processing of PN and the development of PN products.

Mathematical modelling, energy consumption, and quality evaluation of wheat seeds subjected to intermittent drying

AbstractThis work aims to evaluate the kinetic profile of intermittent drying of wheat seeds using traditional models from the literature and the fractional calculus technique. Furthermore, it aims to verify the application of the intermittent drying process on the amount of antioxidant compounds, protein, and lipid content of the grain, in addition to energy consumption to obtain the desired final moisture content of the wheat. It was verified that the prediction of drying kinetics by Page and fraction order models were similar (modelling efficiency varying between the range of 0.917–0.995, varying the drying condition and wheat cultivar). Regarding antioxidant compounds for the three wheat cultivars, it can be seen that the higher fraction of ethanol (74.0% and 90.36%) used for extraction had greater process efficiency. Regarding the protein content in the three wheat cultivars, lower drying temperatures and intermittency periods result in lower quality losses of material (12.3% for BRS‐Atobá wheat, 9.89% for BRS‐Jacana wheat, and 18.71% for BRS‐Sanhaço wheat). In terms of lipids, it was found that the influence of temperature was greater on the lipid content than on the protein content of the material (for the best drying condition, there were percentage decreases for the best condition of 36.16% for the BRS‐Atobá wheat, 34.9% for BRS‐Jacana, and 52.2% for BRS‐Sanhaço). Regarding energy consumption during the drying process, it can be seen that the conditions used for intermittency and drying time, in addition to the sample conditions, directly impact energy consumption.

Simulation study on additive-promoted microwave dehydration of lignite

ABSTRACT Microwave dehydration technology has been widely used in coal processing methods due to its unique advantages. Adding additives with high dielectric loss to coal can enhance the microwave absorption capacity of coal, so as to effectively improve the dehydration process. In order to understand the change and distribution of multi-fields in the microwave drying process of lignite under the action of different additives, verify the experiment and reduce the cost and number of experiments, this paper established a multi-field coupling model of electromagnetic field and heat and mass transfer of multiphase porous media based on COMSOL Multiphysics, so as to simulate the microwave drying process of lignite. The results show that the distribution areas of electromagnetic field, temperature field, and vapor in coal are basically the same, while the distribution of liquid water is just the opposite. With the enhancement of additive promotion effect, the parts with strong electromagnetic field strength increase, the hot spots of temperature field increase, the maximum temperature, and minimum temperature increase, and the water content in coal samples decreases. The promotion effect of additives on the microwave dehydration process of lignite is consistent with the experiment.

A numerical investigation on the conductive drying process for phosphate sludge

Phosphate production generates huge quantities of waste materials that pose both economic and environmental challenges. They are characterized by a high-water content, making disposal a very difficult task. To address this issue, conductive drying emerges as a viable solution to reduce the water content in the phosphate sludge to facilitate handling and specially recycling them as construction materials. This paper presents a simplified numerical model based on Fick's law, depicting heat and mass transfer in porous media to simulate the conductive drying process within the phosphate sludge. To provide more accuracy to the numerical model solution, the experimental data are integrated into the numerical model as boundary conditions, enabling the prediction of temperature profiles, thermal conductivity, and effective moisture diffusivity throughout the conductive drying process. The water evaporation capacity is found between 1.25 and 2.1 kg water/m2.h.These findings could be a tool for designing a suitable dryer for phosphate washing sludge.