 IVES 9 IVES Conference Series 9 Adsorption capacity of phenolics compounds by polyaniline materials in model solution

Adsorption capacity of phenolics compounds by polyaniline materials in model solution

Abstract

AIM: The aim of this work was to study the trapping capacity of four polyaniline polymers towards phenolic compounds in wine-like model solutions.

METHODS: The model wine solution was composed of 12% (v/v) and 4 g/L of tartaric acid adjusted to pH = 3.6. A series of centrifuge tubes (15 mL) were filled with 10 mL of model solution enriched with 50 mg/L of five phenolic compounds (i.e., Gallic acid, caffeic acid, (+)-catechin, (-)-epicatechin, and rutin), and treated with different doses of PANI polymer (i.e., 0, 2, 4 and 8 g/L). After the addition of the polymer, the samples were stirred using a platform shaker at room temperature (20 ºC) for 2, 8, 16 and 24 h. All treatments included three replications. The synthesis and characterization of polyaniline emeraldine base (PANI-EB) and different PANI 50, 100, 150 (polyaniline-PVPP composites where 50, 100, 150 are amount of PVPP) was prepared according to what was reported by Marican et al. (2014). Once the selected contact times were over, the samples were filtered and were by HPLC-DAD, following the methodology described by Gómez-Alonso et al. (2007). In brief, the separation was performed using a reverse-phased LiChrosorb® RP-18 (5 μm) column (250 mm × 4 mm ID) operating at 20 ºC. The injection volume was 25 μL, and for detection and quantification of compounds, the chromatograms were recorded at 280, 320 and 360 nm.

RESULTS: Regardless of the polymer used, the compounds having more affinity for PANI were gallic and caffeic acid, whereas rutin and (+)-catechin were the least removed. For instance, the adsorption percentage of gallic and caffeic acid, with a 4 g/L PANI concentration and 8 h of contact time, reached more than 90% whereas the removal of rutin was lower than 40%. Instead, the phenolic concertation of the samples where no polymer was added (0 g/L of PANI) remain stable over time, very close to 50 mg /L for each of the phenols evaluated. As expected, the concentration of the five phenols decreased as the contact time increased. As an example, a 2 g/L addition of PANI 50 produced a reduction of (-)-epicatechin concentration of 17 mg/L after 8 h of contact time and 25 mg/L after 24 h. Like so, the decrease in the concentration of all phenols was greater when more polymer was added.

CONCLUSIONS: The results obtained suggest that PANI Polymers could be an interesting alternative for analytical or experimental applications in which polyphenolcs need to be removed.

DOI:

Publication date: September 28, 2021

Issue: Macrowine 2021

Type: Article

Authors

María Navarro, JOHN AMALRAJ, V. FELIPE LAURIE

Talca University

Contact the author

Keywords

pani polymers, phenols, model wine solutions

Citation

Effect of multi-level and multi-scale spectral data source on vineyard state assessment

Currently, the main goal of agriculture is to promote the resilience of agricultural systems in a sustainable way through the improvement of use efficiency of farm resources, increasing crop yield and quality under climate change conditions. This last is expected to drastically modify plant growth, with possible negative effects, especially in arid and semi-arid regions of Europe on the viticultural sector. In this context, the monitoring of spatial behavior of grapevine during the growing season represents an opportunity to improve the plant management, winegrowers’ incomes, and to preserve the environmental health, but it has additional costs for the farmer. Nowadays, UAS equipped with a VIS-NIR multispectral camera (blue, green, red, red-edge, and NIR) represents a good and relatively cheap solution to assess plant status spatial information (by means of a limited set of spectral vegetation indices), representing important support in precision agriculture management during the growing season. While differences between UAS-based multispectral imagery and point-based spectroscopy are well discussed in the literature, their impact on plant status estimation by vegetation indices is not completely investigated in depth. The aim of this study was to assess the performance level of UAS-based multispectral (5 bands across 450-800nm spectral region with a spatial resolution of 5cm) imagery, reconstructed high-resolution satellite (Sentinel-2A) multispectral imagery (13 bands across 400-2500 nm with spatial resolution of <2 m) through Convolutional Neural Network (CNN) approach, and point-based field spectroscopy (collecting 600 wavelengths across 400-1000 nm spectral region with a surface footprint of 1-2 cm) in a plant status estimation application, and then, using Bayesian regularization artificial neural network for leaf chlorophyll content (LCC) and plant water status (LWP) prediction. The test site is a Greco vineyard of southern Italy, where detailed and precise records on soil and atmosphere systems, in-vivo plant monitoring of eco-physiological parameters have been conducted.

Evaluation of climate change impacts at the Portuguese Dão terroir over the last decades: observed effects on bioclimatic indices and grapevine phenology

In the last decades the growers of the Portuguese Dão winegrowing region (center of Portugal) are experiencing changes in climate that are influencing either grape phenology berry health and ripening. Aiming to study the relationships between climate indices (CI), seasonal weather and grapevine phenology, in this work long-term climate and phenological data collected at the experimental vineyard of the Portuguese Dão research centre between 1958 and 2019 (61 years) for the red variety Touriga Nacional, was analyzed. The trends over time for the classical temperature-based indices (Growing Season Temperature – GST -, Growing Degree Days – GDD, Huglin Index – HI and Cool Night Index – CI) presented a significantly positive slope while the Dryness Index (DI) showed a negative trend over the last 61 years. Regarding grapevine phenology, an average advance of 4.5 days per decade in the harvest day was observed throughout the last 61 years. Consequently, the weather conditions during the ripening period have changed, showing an increasing trend over time in the average temperature (higher magnitude in the maximum than in the minimum temperature) and a decrease in the accumulated rainfall. A regression analysis showed that ~50% of harvest date variability over years was explained by the temperature-based indices variability. These observed effects of climate change on bioclimatic indices and corresponding anticipation of harvest date can still be considered advantageous for the Dão terroir as it allows to achieve an optimal berry ripening before the common equinox rains and, therefore, avoid the potential negative impacts of the rainfall on berry health and composition.

Effects of graft quality on growth and grapevine-water relations

Climate change is challenging viticulture worldwide compromising its sustainability due to warmer temperatures and the increased frequency of extreme events. Grafting Vitis vinifera L.

Climate, Viticulture, and Wine … my how things have changed!

The planet is warmer than at any time in our recorded past and increasing greenhouse emissions and persistence in the climate system means that continued warming is highly likely. Climate change has already altered the basic framework of growing grapes for wine production worldwide and will likely continue to do so for years to come. The wine sector can continue to play an important role in leading the agricultural sector in addressing climate change. From developing on…

Mesoclimate impact on Tannat in the Atlantic terroir of Uruguay

The study of climate is relevant as an element conditioning the typicity of a product, its quality and sustainability over the years. The grapevine development and growth and the final grape and wine composition are closely related to temperature, while climate components vary at mesoscale according to topography and/or proximity to large bodies of water. The objective of this work is to assess the mesoclimate of the Atlantic region of Uruguay and to determine the effect of topography and the ocean on temperature and consequently on Tannat grapevine behavior.