Impact of the Extraction Method on the Physicochemical, Rheological and Flocculating Properties of an Aloe vera Bioflocculant

Abstract

Water pollution requires sustainable treatment alternatives. The use of Aloe vera bioflocculants to replace synthetic flocculants was evaluated. The raw material was collected from Tierra Blanca, Veracruz, Mexico; and the aloin was removed by immersion (water, 48 h). The gel was separated, cut, crushed and homogenized. Extraction by maceration was first carried out by immersion with water (S/L ratio 1:1, 24 h) and then with ethanol (96 %, S/L ratio 1:3, 24 h). While microwave extraction with ethanol (96 %, S/L ratio 1:3, 5min with 0.5 min pulses and 800 W ). The extracted bioflocculant was dried (45 °C, 6 h ) and grinded. The physicochemical characterization of the gel and bioflocculant was carried out considering moisture, total solids, °Brix, pH, reducing sugars, total carbohydrates, malic acid; the performance was done in terms of rheological properties (viscosity, consistency index and flow behavior) and turbidity reduction (NTU). The highest content of soluble solids, malic acid, ºBrix, reducing sugars and total carbohydrates was observed in the bioflocculant. The gel and bioflocculant showed a non-Newtonian pseudoplastic behavior with the Otswald model (R2 > 0.99, and n <1) and the greatest reduction in turbidity was observed at pH 7.5 in both gel and bioflocculant (78.31 %). The above regardless of the extraction method, microwave extraction requires less time to obtain the biofloculant A. vera, but had no effect on its physicochemical, structural, rheological and flocculating properties, representing a sustainable and ecological alternative for replacing synthetic flocculants.