The Role of Cations in Resorcinol–Formaldehyde Gel Textural Characteristics

The production of resorcinol–formaldehyde xerogels has yielded insight into the gelation processes underpinning their structures. In this work, the role of the cation species from the catalyst is probed by studying the simultaneous addition of sodium carbonate and calcium carbonate to a resorcinol–formaldehyde mixture. Twenty-eight xerogels were prepared by varying the solids content, catalyst concentration, and catalyst composition, and each was analysed for its textural properties, including the surface area and average pore diameter. The results indicate that the role of the cation is linked to the stabilisation of the clusters formed within the system, and that the Group II catalyst causes the salting out of the oligomers, resulting in fewer, larger clusters, hence, an increase in pore size and a broadening of the pore size distribution. The results provide insight into how these systems can be further controlled to create tailored porous materials for a range of applications.

Influence of Carbon Sorbent Quantity on Breakthrough Time in Absorbent Filters for Antismog Half Mask Application

In this article, we present polymer non-woven fabrics with the addition of carbon sorbents being tested to estimate the breakthrough time and efficient protection against vapors present in smog. For this purpose, three substances were selected, which constitute an inhalation hazard and are smog components: cyclohexane, toluene, and sulfur dioxide. It was demonstrated that an increased quantity of carbon sorbent in polymeric filters significantly prolongs the breakthrough time. However, high sorbent quantities may increase the filter surface mass and air flow resistance. To optimize the protective parameters with functionality, a compromise between the two has to be found. By comparing the breakthrough times for different carbon sorbent quantities, the optimal filter composition was elaborated. The analyzed non-woven fabrics were manufactured by the melt-blown process and filled with ball-milled carbon sorbents supplied directly into the fabric blowing nozzle. Both protective performance and textural properties were analyzed for two commercially available carbon sorbents. Furthermore, it was proven that high values of sorbent-specific surface area translates directly into greater filter performance.

Dealing with Plastic Waste from Agriculture Activity

The increase in agricultural production and food quality has forced the growing use of plastics in various activities. The plastic wastes are partially recycled in or outside Portugal; nevertheless, the contaminated wastes are sent to landfill. It is crucial to consider new models for their valorization at a regional level and from a circular economy perspective. In the scope of the Placarvões project, a study was elaborated, which included the types and quantities of plastics used in the irrigation area of the Alqueva Dam, in southern Portugal. The crops that use the most plastic are intensive olive groves, almonds, and table grapes, which represent more than 91% of total plastic waste. The production of activated carbons (ACs) is a solution to avoid plastics landfill. ACs were produced from plastic used on food packaging (PB-Samples) and sheeting film (PS-Samples) by activation with K2CO3. ACs presented well-developed textural properties (PB-K2CO3-1:1–700 and PS-K2CO3-1:1–700 exhibited a volume of 0.32 and 0.25 cm3 g−1 and an apparent surface area of 723 and 623 m2 g−1, respectively). Both ACs performed very well concerning four pesticide removals from the liquid phase. This solution is very promising, such these ACs could be applied in effluent treatments on a large scale.

Determination of The Physical, Physio-Chemical and Chemical Properties of Gilaburu Fruits (Viburnum opulus) Dried by Convectional Drying Technique

Our country has many species in fruit and vegetable cultivation. One of them is Gilaburu fruit (Viburnum Opulus), which has spread to different regions, especially in Kayseri. Longer preservation of products in fruits and vegetables; Drying process has been applied since ancient times to prevent deterioration caused by microbial and/or biochemical changes. One of them and the most common one is convectional drying in other words drying in a drying chamber under controlled hot air stream. In this study, Gilaburu fruits were obtained from a local producer in Kayseri. Drying processes were carried out in a convectional oven at 60, 70 and 80℃ in three repetitions. The effects of different drying conditions on the drying characteristics of Gilaburu fruits were examined. Drying time for Gilaburu fruits decreased with increasing temperature. As a color parameter total color change with respective to fresh fruit (ΔΕ) was investigated. The results indicated that it remained almost identical with temperature change. Similar trend was observed for rehydration rate. Titration acidity and pH values showed compatible changes. With temperature increase, titration acidity increased, as pH decreased. As textural properties, skin-hardness and elasticity of dried fruits were measured. As hardness increased, elasticity decreased with temperature elevation. Total phenolic content and antioxidant activity of dried samples were also examined. The results showed that there were increases in both of them with an increase in temperature.

Effect of Dairy, Season, and Sampling Position on Physical Properties of Trentingrana Cheese: Application of an LMM-ASCA Model

Trentingrana hard cheese is a geographic specification of the PDO Grana Padano. It is produced according to an internal regulation by many cooperative dairy factories in the Trentino region (northern Italy), using a semi-artisanal process (the only allowed ingredients are milk, salt, and rennet). Within the PSR project TRENTINGRANA, colorimetric and textural measurements have been collected from 317 cheese wheels, which were sampled bi-monthly from all the consortium dairies (n = 15) within the timeframe of two years, to estimate the effect on physical properties related to the season of the year and the dairy factory implant. To estimate the effect of the dairy and the time of the year, considering the internal variability of each cheese wheel, a linear mixed-effect model combined with a simultaneous component analysis (LMM-ASCA) is proposed. Results show that all the factors have a significant effect on the colorimetric and textural properties of the cheese. There are five clusters of dairies producing cheese with similar properties, three different couples of months of the year when the cheese produced is significantly different from all the others, and the effect of the geometry of the cheese wheel is reported as well.

Evaluation of the reactivity, selectivity and lifetime of hydrotalcite-based catalysts using isopropanol as probe molecule

Hydrotalcite catalysts derived from NiAl and NiAlMg mixed oxides were successfully prepared by coprecipitation at a constant pH of 11. Physicochemical methods were investigated to determine their structural and textural properties. Using isopropanol as a probe molecule, the acid–base properties of the catalysts were investigated, and the evaluation of reactivity, selectivity and lifetime was established.