Solar hydro-distillation (SHD) is presented as a new green technique to effectively extract the various phytochemicals from food by-products. To better understand the procedure, results, and advantages of such a green and sustainable source, the goal of this study was to compare the efficiency of SHD to extract essential oils from Pelargonium graveolens (L'Hér) while simultaneously releasing antioxidant compounds like polyphenols and flavonoids in the remaining phase of the solar still. The yields of the essential oils were 0.64 % and 0.60 % for SHD and conventional hydro-distillation (CHD), respectively. By using GC-MS analysis, 52 volatile components were identified. Citronellol (27.54 %-26.51 %), citronellyl formate (13.63 %-11.33 %), geraniol (11.94 %-10.97 %) and geranyl formate (8.31 %-5.84 %) represented the main components for SHD and CHD oils, respectively. For the extracts produced by SHD and maceration, total phenolic compounds (TPC), total flavonoid compounds (TFC), and antioxidant activity (AA) based on 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity were evaluated. The results showed that the SHD extract produced an extremely good extraction yield in TPC, TFC, and IC50 (249.72 mg EAG.g-1 DM, 205.88 mg EQ.g-1 DM, and IC50=6.54 μg.mL-1, respectively). Moreover, HPLC-UV analyses showed conservation in the extract after the SHD process of some identified compounds such as tyrosol (31.71 mg.g-1 DM), gallic acid (24.67 mg.g-1 DM), protocatechuic acid (22.59 mg.g-1 DM), and ferulic acid (21.04 mg.g-1 DM). On the other hand, the essential oil and the extract prepared by SHD showed an important anti-cyanobacterial/anti-algal activity against the bacterial/algal strain tested Microcystis aeruginosa and Chlorella sp., with growth inhibition diameters of 15.43 ± 0.32 mm, 16.73 ± 0.40 mm and 17.13 ± 0.35 mm, 25.96 ± 0.15 mm respectively for essential oil and extract. A positive linear correlation was observed between antioxidants, polyphenols, flavonoids and anti-cyanobacterial/anti-algal activity for solar extracts. Results showed that SHD is a good alternative for recovering bioactive compounds from the Pelargonium graveolens (L'Hér.) with potent antioxidant, and anti-cyanobacterial/anti-algal activity.

The drying of hydroxide sludge is a critical step in its valorization process in drinking water treatment plants (WWTPs), due to the high energy requirements associated with this operation. This study investigates the convective drying behavior of hydroxide sludge using a convective micro-dryer, with air heated to temperatures between 70 °C and 110 °C, velocities ranging from 1 m/s to 3 m/s, and constant absolute humidity of 0.005 kg of water per kg of dry air. The process was continuously monitored through X-ray microtomography, allowing the nondestructive observation of external surface texture evolution, shrinkage, and crack formation. A significant shrinkage, with a volume reduction ranging from 30% to 45%, was observed as the moisture content decreased. The experimental data were used to develop a characteristic drying curve specific to hydroxide sludge, which remained consistent across different operational conditions. The results showed that increasing air temperature and velocity enhanced the drying flux and reduced drying time, while higher air humidity produced the opposite effect. Additionally, the crack formation observed towards the end of the drying process was associated with internal moisture transfer limitations. Effective diffusivity increased with air temperature, highlighting the significant impact of temperature on the activation energy of the drying process. These findings provide valuable insights for optimizing the energy efficiency of sludge-drying operations.

The agricultural industry is a vital sector in many countries, significantly contributing to employment through both direct and indirect links with food processing and distribution. This research is a sustainable and ecofriendly solution, to conserve two apricot varieties, Carmen and Aurora, in Morocco's agri-food industry. Utilizing an indirect convective solar dryer under various aero-thermal conditions, the study demonstrates a notable decrease in moisture content for Carmen and Aurora apricots, from initial values of 86.38 % and 82.75 % respectively, to 26.78 +/- 3 % (wet.basis). By examining the drying kinetics of apricot slices, the research establishes diffusion coefficients ranging from 4.65 10-10 to 24.40 10-10 m2/s for Carmen and from 3.24 10-10 to 14.16 10-10 m2/s for Aurora, with the coefficients varying as temperature increases. The Arrhenius equation, indicating an activation energy of 5434.87 kJ/kg, effectively describes the temperature dependency of the diffusion coefficient. Notably, the conductive drying kinetics of apricot slices were found to be best described by the Midilli-Kucuk model. The overall energy consumption exhibited a downward trend as temperatures increased and an upward trend with higher airflow rates. Additionally, the findings showed that higher air temperatures led to better energy efficiency. To assess the performance of the solar dryer being studied, an exergy analysis was conducted. The exergy efficiency of the convective dryer varied between 22.24 % and 54.12 % for Aurora, and between 31.6 % and 57.32 % for Carmen. This innovative approach highlights the potential of green energy in enhancing agricultural practices and product preservation.

Aromatic and medicinal plants are a natural source of pharmaceutical compounds with curative and therapeutic properties. They have been used for centuries to treat various ailments and offer alternative options to conventional treatments. Among these plants, Marrubium vulgare L., which is widely used in traditional medicine for diabetes treatment, has antioxidant potential as well as anti-inflammatory, healing, and soothing properties, attracting increasing medical interest. In this context, the hygroscopic behavior of Marrubium vulgare L. is reported. The adsorption-desorption isotherms of Marrubium vulgare leaves were determined using the standard static gravimetric method at three temperatures (30, 40, and 50 °C) to ensure physicochemical and microbiological stability throughout the storage process. The results showed that the adsorption-desorption isotherms of all samples followed a sigmoidal pattern, consistent with other agricultural products discussed in the literature. The optimal moisture content for conservation was also determined. The GAB (Guggenheim-Anderson-de Boer) and double polynomial models were the most suitable for describing the sorption curves. The adsorption-desorption data were examined to determine the moisture content of the monolayer (3.4-9.7%), properties of sorbed water in porous structures and surfaces, total heat of wetting, net isosteric heat of sorption, spreading pressure, differential entropy, and enthalpy-entropy compensation. It was also observed that the spreading pressure and average pore radius increase with rising relative humidity and temperature, leading to the appearance of defects on the surface of Marrubium vulgare leaves. Compensation theory is essential to consider when evaluating the impact of temperature on the adsorption-desorption properties. The Gibbs free energy was positive for sorption, indicating that the process is non-spontaneous.

Phosphate extraction process produces large amounts of waste sludge, that is disposed of in the environment. Phosphate sludge (PS) is characterized by high moisture content (70-80%) which is a major handicap for any further disposal. To overcome this issue, the drying of this waste could be an appropriate solution to minimize its volume. The present work is focused on the convective drying behavior of PS and its mathematical modeling to optimize the drying processes. Drying experiments were conducted using thicknesses of 1, 2 and 4 cm. Drying air temperature and velocity ranged respectively in 50-70°C and 1-2 m/s. The findings showed that improving drying air temperature and velocity, and decreasing sample thickness enhance considerably the drying rate. Furthermore, the drying curves showed the presence of two main drying periods corresponding to constant drying rate and falling drying rate periods. Moreover, a model considering heat and mass transfer equations for each phase in wet sludge was used to fit the experimental results. Based on the analytical solutions and according to the statistical criteria R2 and RMSE ranged from 0.9957-0.9996 and 0.0157-0.0276, respectively, it was concluded that the model describes the drying behavior of washing PS in all tested convective drying conditions. This study advances drying efficiency and opens pathways for improved handling and storage of phosphate sludge waste.

This study investigates the hygroscopic properties of Compressed Earth Bricks (CEB) stabilized with varying amounts of bentonite and cement, ranging from 0 % to 8 %. The primary aim is to assess how these stabilizers influence moisture retention and regulation under different temperature conditions. Experimental analyses were conducted at 30 degrees C, 40 degrees C, and 50 degrees C, with relative humidity levels spanning from 5 % to 90 %. The findings indicate that cement incorporation decreases moisture absorption and enhances the bricks' resistance to climatic fluctuations. However, at elevated humidity levels, structural imperfections emerged, likely due to modifications in the material's pore network. To further understand these moisture interactions, analytical methods were employed, offering valuable insights into the material's response to diverse environmental conditions. These results contribute to optimizing CEB formulations for improved durability and adaptability in sustainable construction across various climates.

Current study aims to analyze the drying kinetics of madder roots. To accomplish this, a conventional solar dryer was utilized to generate drying curves at 50, 55, and 60 degrees C, as drying temperatures. These curves were then fitted using established drying models. The results obtained from the experimental drying curves demonstrate that the drying rate is strongly impacted by the air conditions inside drying chamber. Current study employed ten drying models to model the drying curves, and for madder roots Midilli & Kucuk model demonstrated an accurate describing of drying kinetics with a correlation coefficient of 0.999.

The research article aims to investigate the hygroscopic behavior of water absorbed by capillarity in clay supplemented with Alfa fibers. This specific clay-fiber composite holds significant importance in Moroccan construction practices. The primary aim is to enhance comprehension and control over the material's hydrothermal behavior by investigating moisture absorption traits, responses to varying humidity and temperature conditions, and the influence of fiber reinforcement on moisture equilibrium and structural stability. As temperature levels rise, the equilibrium water content absorbed through capillarity demonstrates a downward trend. The introduction of Kaolin-Alfa fibers into the clay composite profoundly affects the pace at which equilibrium moisture content is lost. This attribute effectively mitigates the likelihood of cracks developing in earthen structures during the drying phase, as it uniformly disperses tensions resulting from shrinkage. The findings showed that by understanding its unique region, Predictions regarding the sorption tendencies of other building materials are possible because of the approximate estimation of Clay-Kaolin reinforced with Alfa fibers sorption behavior. Surface flaws arise on Clay-Kaolin reinforced with Alfa fibers as a result of rising average pore radius and spreading pressure brought on by rising temperature and relative humidity. Furthermore, the heightened average pore volume observed in regions characterized by elevated relative humidity levels precipitates various defects within building materials, a phenomenon that has a discernible impact on their durability.

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.

The significant production of sewage sludge by wastewater treatment plants on a global scale and the lack of correspondence between housing development and the expansion of sanitation infrastructure indicate a genuine concern regarding environmental preservation. This study addresses the crucial issue of effective sewage sludge management and its environmental impact. In the context of searching for new drying methods that optimize energy use and effectively stabilize sewage sludge, this work investigates the drying behavior of sewage sludge from treatment plants in two northern Moroccan cities using a prototype of an indirect forced convection solar dryer. The drying experiments enabled the determination of drying kinetics and highlighted the influence of temperature and humidity on the drying rate. The characteristic drying curve (CDC) and its mathematical expression were determined using Van Meel's formalism. Thermal diffusivity of wastewater sludge during drying was also investigated. Using Fick’s diffusion model, diffusion coefficients ranged between 0.59 × 10⁻⁹ m²/s and 1.43 × 10⁻⁹ m²/s, demonstrating an increase in effective diffusivity with rising temperature. The Arrhenius equation provided activation energy values of 16.80 kJ/mol for Oujda samples and 19.72 kJ/mol for Nador samples, indicating the effect of temperature on effective diffusivity. A new equation based on the Midilli-Kucuk model was proposed to predict drying behavior under untested aerothermal conditions, considering drying temperature and the initial dryness. This study offers a comprehensive analysis of the drying kinetics and effective diffusivity of sewage sludge, providing valuable insights for designing large dryers for sludge management in WWTPs. This approach presents an optimal solution for drying and stabilizing sludge, contributing to environmental preservation efforts.

In this study, a controlled indirect solar dryer was used to dry dandelion roots at three temperatures of 60 degrees C, 70 degrees C, and 80 degrees C, together with two air flow rates of 0.0417 m(3)/s and 0.0834 m(3)/s. The main aim of this research is to carry out an exergetic analysis on the dryer chamber and the drying process in order to improve the exergetic efficiency of the solar dryer. The outcomes showed that the level of exegetic performance depends on the variation of the operating conditions. The exergy yield of the drying chamber of six drying configurations was obtained between the ranges of 48.1141%-68.2755%.

Current study investigated the sorption proprieties of madder roots. Sorption isotherms were measured through a gravimetric static technique using chemical salts, to control the surroundings water activity in a range of 0.05-0.9. Sorption measurements were conducted in three temperature 20, 30, and 40 degrees C. Integral proprieties were evaluated through Clausius-Clapeyron equation for a constant value of spreading pressure. In this study the optimal conditions for storage of madder roots were discussed in the indicated interval of temperature. The study findings showed that the madder roots isotherms were type II and the moisture content of product increased with the increase of water activity. Peleg and GAB models showed highly performance in fitting the sorption data. Integral entropy exhibited a minimum value in the region of 6-7% db, and 0.34-0.38 for moisture content and relative humidity, respectively. These conditions were considered as the best to preserve the madder roots shelflife.

This paper presents a case study of solar drying of hydroxide sludge in the region of Marrakesh, Morocco. The experiments of solar greenhouse drying processes of the hydroxide sludge were studied in summer and winter seasons. The representative samples were in three volumes. The greenhouse sludge dryer was designed and constructed as a horticultural plant. Results showed that the dry of the three samples was reached in only 13 hours in summer and 25 hours in winter. The time of solar greenhouse drying registered was significantly lower compared to several studies. The higher values of drying rate were obtained in early hours of experiments in summer. The maximum ranges obtained were 0.25 kg water/kgDS.h for the hot season and 0.020 kg water/kgDS.h for the cold season. The important influence of the temperature had a greater effect with wind speed on drying rate. The sludge water evaporation caused a large volume reduction with a shrinkage during the processes in both seasons.

The present work analyzes the drying kinetics of food waste, focusing on the effects of temperature, airflow and drying on biogas production. The work involves the experimental determination of food waste drying kinetics under controlled environmental conditions, including modeling the curves using a mathematical model. Indirect solar drying experiments of food waste have been performed at different air flow rates (300 m(3).h(-1) and 150 m(3).h(-1)) and temperature values (40, 50, 60, and 70 degree celsius). The temperature in the drying room was adjusted to the desired level using an auxiliary electric heating system. Energetic and environmental performance metrics of different air flow rate and temperature configurations have also been investigated and presented within the scope of this work. Additionally, an experimental investigation to measure the biogas generated by the fermentation of dried food waste was conducted. It was established that a logarithmic model best captures the drying kinetics, and the temperature and airflow are crucial variables. Increasing the drying temperature from 40 degree celsius to 70 degree celsius for the tests that performed in lower and higher flow rates improved the specific moisture extraction rate as 45.02 % and 130.65 %, respectively. It can also be observed that only phase 2 is present in the drying curve, phases 0 and 1 are absent. Furthermore, drying decreases the generation of biogas, which is primarily composed of methane, a potent greenhouse gas, according to experimental studies.

AbstractDrying, an age‐old method of food preservation, involves the concurrent exchange of heat and mass, resulting in reduced moisture content. The current study is based on experimental approach to evaluate the impact of combined microwave and solar drying on the drying kinetics and the energy efficiency of truffle drying. This study explores the impact of a 4‐min microwave pretreatment on the solar drying of truffle slices. The findings demonstrate that microwave treatment significantly reduces the time required for solar drying. When compared to solar drying without pretreatment, microwave treatment leads to a reduction in drying time ranging from 23.07% to 70.37% at temperatures between 50 and 80°C. The Midilli–Kucuk model is employed to elucidate the experimental results, revealing strong fits with high correlation coefficients and low standard error values. Microwave pretreatment enhances the drying rate of truffle slices, resulting in a higher effective moisture diffusivity compared to untreated slices. The activation energy for drying also decreases from 76.37 to 25.25 kJ/mol after microwave pretreatment. An energy analysis of the drying process underscores that elevating the drying air temperature reduces energy consumption. Furthermore, the proposed microwave pretreatment influences the energy efficiency of the drying process.

The solar drying method consists of removing gartially and non-bound water with a small impact on the chemical structure and compositions, thus reducing the mass and minimizing the risk of numerous transformations. Taraxacum officinale leaves are well-known in the fields of pharmacology, herbal medicine, and traditional soft drinks. Since it is a seasonal plant, plants from these regions have become an indispensable element after drying and storing. The objective of this paper is to determine both total and specific energy consumption of the hybrid solar convection dryer in drying Taraxacum officinale leaves. The paper investigates the energy analysis of the leaves of Taraxacum solar drying, which includes the investigation of the impact of the aerothermal parameters’ variations: 4 temperatures (50, 60, 70, and 80°C) and 2 drying airflows (150 and 300 m3 h–1) on the specific energy utilization in the drying process. Furthermore, this work studies the thermal efficiency as well as the energy efficiency of the solar dryer which gives room to maximize the performance of the dryer chamber. The results indicate minimal values of total energy consumption are achieved at higher temperatures and airflow rates. The findings reveal that lower total energy consumption is achieved at higher temperatures and airflow rates. Moreover, the study delves into thermal efficiency and energy efficiency, highlighting a thermal efficiency of approximately 5.58

Apricots offer diverse health benefits, making them a valuable component of an attractive diet. In addition to ensuring the physicochemical and microbiological stability during storage and the year-round availability of this nutrient-dense fruit, apricot preservation, especially through sorption isotherm processes, also considers economic, nutritional, and environmental factors. In the same context, this study explores the analysis of two common apricot cultivars in Morocco. The primary objective is to determine the optimal conditions for storing and conserving the investigated products using the standard gravimetric static method at 30 °C, 40 °C, and 50 °C—six one-liter glass jars with insulated lids made up the experimental set-up. A fourth of the glass jar was filled with a saturated salt solution. Weighing 0.100 g (±0.001) g for adsorption and 0.200 g (±0.001) g for desorption, duplicate samples were precisely weighed and put into the glass jars. The outcomes revealed that the adsorption-desorption isotherms for all samples conformed to the characteristic Type II sigmoid pattern. The ideal water activity values to preserve “Aurora” and “Carmen” are 0.36 and 0.38, respectively. It was determined that the best model to describe the sorption curves of “Aurora” and “Carmen” was LESPAM. Analysis of the adsorption-desorption data aimed to determine the moisture content of the monolayer (ranging from 3.4 to 9.7

This study investigates the influence of drying temperature on the conductive drying behavior of washing phosphate sludge. A mathematical model, based on Fourier's Fick diffusion law and the heat transfer equation, was developed to simulate coupled heat and mass transfer during the drying process, incorporating the shrinkage effect. The sludge samples, obtained from the Khouribga phosphate plant in Morocco, were subjected to drying at temperatures of 70°C and 95°C. The experimental setup included continuous monitoring of temperature, humidity, and mass loss throughout the process. COMSOL Multiphysics software was used to solve the nonlinear equations governing heat and mass transfer. Results indicate that increasing the drying temperature significantly accelerates the drying rate. The model successfully predicts the moisture content and temperature distribution over time, aligning well with experimental data. Statistical validation, using the determination coefficient (R²) and root mean square error (RMSE), confirms that the model accurately describes the drying behavior, with R² values of 0.9957 and 0.9967 at 70°C and 95°C, respectively. The inclusion of the shrinkage effect enhances the model's precision in describing the drying kinetics under varying conditions.