Historically, there is evidence to suggest that communities in the developing world have used plant-based materials as one strategy for purifying drinking water. In this study, the coagulant properties of Opuntia spp., a species of cactus, are quantitatively evaluated for the first time. Opuntia spp. was evaluated for turbidity removal from synthetic water samples, and steps were made toward elucidating the underlying coagulation mechanism. In model turbid water using kaolin clay particles at pH 10, Opuntia spp. reduced turbidity by 98% for a range of initial turbidities. This is similar to the observed coagulation activities previously described for Moringa oleifera, a widely studied natural coagulant. Although it has been reported that Moringa oleifera predominantly operates through charge neutralization, comparison of zeta potential measurements and transmission electron microscopy images of flocs formed by Opuntia spp. suggest that these natural coagulants operate through different mechanisms. It is suggested that Opuntia spp. operates predominantly through a bridging coagulation mechanism. Once optimized, application of these readily available plants as a part of point-of-use water treatment technology may offer a practical, inexpensive, and appropriate solution for producing potable water in some developing communities.

Toward Understanding the Efficacy and Mechanism of Opuntia spp. as a Natural Coagulant for Potential Application in Water Treatment

https://profdoc.um.ac.ir/articles/a/1011802.pdf

Response surface methodology for optimization of extraction yield, viscosity, hue and emulsion stability of mucilage extracted from Lepidium perfoliatum seeds

Metal and polymer based materials are the conventional coagulants used in water and wastewater treatment operations. Despite the wide applicability of these genera of coagulants, the challenges associated with the usage have engendered research efforts towards the development of green biobased coagulants, whose applications are capable of obviating the challenges synonymous with the usage of these conventional coagulants. Taking into cognizance the goals that informed the development of green technology, perspectives on the promising non-conventional coagulants that are green and biobased are presented in this treatise. The perspectives on these green biobased coagulants were anchored on the background information of the material, the economic importance, mode of application of the extract as coagulant, underlying coagulating mechanism and the shortcomings of the usage in water and wastewater treatment operations. On the basis of the information provided by different researchers, on the appraisals of these green biobased coagulants for water and wastewater treatment operations, the factors militating against the transition of the applications of these non-conventional coagulants from bench-scale to real life applications were discussed.

Headway on natural polymeric coagulants in water and wastewater treatment operations

Polysaccharide extraction from Abelmoschus esculentus: Optimization by response surface methodology

Mucilage of Opuntia ficus-indica (OFI) was extracted and characterized by its composition and molecular weight distribution. Mucilage film-forming dispersions were prepared under different pHs (3, 4, 5.6, 7, and 8) and calcium concentration (0% and 30% of CaCl(2), with respect to mucilage's weight), and their particle size determined. Mucilage films with and without calcium (MFCa and MF, respectively) were prepared. The effect of calcium and pH on mucilage films was evaluated determining thickness, color, water vapor permeability (WVP), tensile strength (TS), and percentage of elongation (%E). The average molecular weight of the different fractions of mucilage was: 3.4 x 10(6) (0.73%), 1 x 10(5) (1.46%), 1.1 x 10(3) (45.79%), and 2.4 x 10(2) Da (52.03%). Aqueous mucilage dispersions with no calcium presented particles with an average size d(0.5) of 15.4 microm, greater than the dispersions with calcium, 13.2 microm. MFCa films showed more thickness (0.13 mm) than the MF films (0.10 mm). The addition of calcium increased the WVP of the films from 109.94 to 130.45 gmm/m(2)dkPa. Calcium and pH affected the mechanical properties of the films; the largest TS was observed on MF films, whereas the highest %E was observed on MFCa films. The highest differences among MF and MFCa films were observed at pHs 5.6 and 7 for TS and at pHs 4 and 8 for %E. No effect of pH and calcium was observed on luminosity and hue angle. Chroma values were higher for MF when compared with MFCa, and increased as pH of the films increased. Practical Application: In this study mucilage from nopal was extracted and characterized by its ability to form edible films under different pHs, and with or without the addition of calcium. Opuntia ficus-indica mucilage had the ability to form edible films. In general, it can be considered that mucilage films without modification of pH and without the addition of calcium have the best water vapor barrier properties and tensile strength. Mucilage from nopal could represent a good option for the development of edible films in countries where nopal is highly produced at low cost, constituting a processing alternative for nopal.

Development and Characterization of Edible Films Based on Mucilage of Opuntia ficus-indica (L.)

http://repositorio.uchile.cl/bitstream/handle/2250/120215/Sepulveda_E.pdf?sequence=1

E. Aliaga

Papers

Extraction and characterization of mucilage in Opuntia spp.