Application of colloidal gas aphron suspensions produced from Sapindus mukorossi for arsenic removal from contaminated soil

Abstract

Colloidal gas aphron dispersions (CGAs) can be described as a system of microbubbles suspended homogenously in a liquid matrix. This work examines the performance of CGAs in comparison to surfactant solutions for washing low levels of arsenic from an iron rich soil. Sodium Dodecyl Sulfate (SDS) and saponin, a biodegradable surfactant, obtained from Sapindus mukorossi or soapnut fruit were used for generating CGAs and solutions for soil washing. Column washing experiments were performed in down-flow and up flow modes at a soil pH of 5 and 6 using varying concentration of SDS and soapnut solutions as well as CGAs. Soapnut CGAs removed more than 70% arsenic while SDS CGAs removed up to 55% arsenic from the soil columns in the soil pH range of 5-6. CGAs and solutions showed comparable performances in all the cases. CGAs were more economical since it contains 35% of air by volume, thereby requiring less surfactant. Micellar solubilization and low pH of soapnut facilitated arsenic desorption from soil column. FT-IR analysis of effluent suggested that soapnut solution did not interact chemically with arsenic thereby facilitating the recovery of soapnut solution by precipitating the arsenic. Damage to soil was minimal arsenic confirmed by metal dissolution from soil surface and SEM micrograph.

Optimization of Microwave-Assisted Extraction Saponins from Sapindus mukorossi Pericarps and an Evaluation of Their Inhibitory Activity on Xanthine Oxidase

“…As it is rich in valuable saponins (possessing the property of outstanding surface activity), S. mukorossi is an ecofriendly and promising alternative material of biosurfactant for producing shampoos, cosmetic cleansers, and detergents in sanitary and cosmetic products [3]. S. mukorossi saponins can be applied to remove heavy metals or hydrocarbons from polluted soil and waste water and for enhancing oil recovery, dye solubilization, and nanoparticle synthesis [4][5][6][7]. Moreover, S. mukorossi saponins are widely applied to pharmaceutical industry, due to its manifold pharmacological effects, including antimicrobial activity [8][9][10][11], antitumor functions [12][13][14], anti-inflammatory effects [15,16], and insecticidal activity [17,18].…”

Colloidal Gas Aphrons separation to obtain polyphenol rich fractions from artichoke agro-industrial discards

“…Furthermore, the use of food grade surfactants, as non-ionic ones leads to a more simplified process as there is no need for their removal (Dermiki et al, 2009;Jauregi and Dermiki, 2010;Spigno et al, 2010). So far, CGAs have been used in the removal of metals, dyes (Huang et al, 2003) and toxic compounds (Mansur et al, 2006;Mukhopadhyay et al, 2015) from wastewaters and other effluents, amongst other applications (Molaei and Waters, 2015).…”

Remediation of heavy metal contaminated soil by biodegradable chelator–induced washing: Efficiencies and mechanisms

“…Previous reports confirmed by XPS that the combination of dithionite and EDTA greatly improved soil arsenic removal because iron oxides-bound heavy metals were transformed to Fe(II,III) or Fe(II) oxide forms under the reduction of dithionite (Kim et al, 2015). The SEM-EDS, FTIR, and XRD elucidated that the predominant mechanisms of saponin enhance PTE removal from soil and sludge were complexation, metalbridging, and solubilization effects (Mukhopadhyay et al, 2015;Tang et al, 2017). Although some efforts in gathering soil spectroscopy characteristics were made during the process (Medina et al, 2017;Hisada and Kawase, 2018;Mu Azu et al, 2018), the available information concerning the metal removal mechanisms via soil washing is still limited especially for BCs such as GCA, GLDA, PASP, and ISA that are new and green alternatives of conventional chelating agents.…”