pectins and arsenic-acid

The low cost and non-toxic of magnesium oxides make it a potential eco-friendly material for arsenic removal. Polysaccharide is a kind of green modifier to obtain nanoscale MgO particles with a higher adsorption affinity. In this study, the impact of chain structures of polysaccharides on the morphology features and arsenate removal efficiency of MgO-NPs were investigated. Pullulan and starch facilitated the synthesis of flower-like MgO-NPs, and pectin facilitated the synthesis of plate-like ones. Although the two kinds of flower-like MgO-NPs undergone similar time to reach equilibrium, the one obtained from the starch-synthesis route showed a higher arsenate adsorption capacity (98 mg g

Topics: Adsorption; Arsenates; Arsenic; Magnesium Oxide; Nanoparticles; Pectins; Polysaccharides; Starch; Water Pollutants, Chemical

High concentrations of arsenic in groundwater continue to present health threats to millions of consumers worldwide. Particularly, affected communities in the developing world need accessible technologies for arsenic removal from drinking water. We explore the application of cactus mucilage, pectic polysaccharide extracts from Opuntia ficus-indica for arsenic removal. Synthetic arsenate (As (V)) solutions were treated with two extracts, a gelling extract (GE) and a nongelling extract (NE) in batch trials. The arsenic concentration at the air-water interface was measured after equilibration. The GE and NE treated solutions showed on average 14% and 9% increases in arsenic concentration at the air-water interface respectively indicating that the mucilage bonded and transported the arsenic to the air-water interface. FTIR studies showed that the -CO groups (carboxyl and carbonyl groups) and -OH (hydroxyl) functional groups of the mucilage were involved in the interaction with the arsenate. Mucilage activity was greater in weakly basic (pH 9) and weakly acidic (pH 5.5) pH. This interaction can be optimized and harnessed for the removal of arsenic from drinking water. This work breaks the ground for the application of natural pectic materials to the removal of anionic metallic species from water.

Topics: Adhesives; Arsenates; Arsenic; Metals, Heavy; Opuntia; Pectins; Polysaccharides; Water Pollutants, Chemical; Water Purification

The role of Fe(III) stored at the soil-root interface in the accumulation of arsenate and the influence of citric acid on the As(V) mobility were investigated by using Ca-polygalacturonate networks (PGA). The results indicate that in the 2.5-6.2 pH range Fe(III) interacts with As(V) leading to the sorption of As(V) on Fe(III) precipitates or Fe-As coprecipitates. The FT-IR analysis of these precipitates evidenced that the interaction produces Fe(III)-As(V) inner-sphere complexes with either monodentate or bidentate binuclear attachment of As(V) depending on pH. In the 3.0-6.0 pH range, As(V) diffuses freely through the polysaccharidic matrix that was found to exert a negligible reducing action towards As(V). At pH 6.0 citric acid is able to mobilize arsenate from the As-Fe-PGA network through the complexation of the Fe(III) polyions that leads to the release of As(V).

Topics: Adsorption; Arsenates; Arsenites; Calcium; Citric Acid; Ferric Compounds; Hydrogen-Ion Concentration; Pectins; Plant Roots; Soil