Saponin Versus Rhamnolipids for Remediation of Cd Contaminated Soils

Abstract

Cadmium should be effectively removed from soil because it is one of the most toxic soil pollutants. Thus, the present study compared a plant (saponin, SAP) and a microbial (rhamnolipids, RAM) biosurfactant for Cd removal from three different types of soil. Batch washing was tested under different operational conditions: Biosurfactant concentration, 0.1–10% SAP, 0.01–1% RAM; washing time, 0.1–6 h; soil dosage, 12.5–100 g L−1; biosurfactant pH, 2–9 for SAP, 5.5–12 for RAM; washing number, three with SAP, four with RAM. SAP removed Cd from the soils more effectively than RAM because it can be used at a higher concentration and a more acidic pH. Soil washing with SAP also has a shorter equilibrium time (10–90 min.) than washing with RAM (50–300 min), and higher kinetic rate constants (0.23–4.9 kg mg · h−1 for SAP, 0.12–0.25 kg mg · h−1 for RAM). With an increase in soil dosage, Cd removal from all soils decreased significantly with both SAP and RAM. Multiple soil washings improved Cd removal. The predicted optimum number of washes depended on the criteria for soil quality assessment, that is, total Cd concentration, Cd mobility or ecological risk. To meet all of these criteria, SAP needed fewer washes than RAM. SAP is more suitable than RAM for treatment of soils highly contaminated with Cd and containing various amounts of clay.

Sequential soil washing with mixed biosurfactants is suitable for simultaneous removal of multi-metals from soils with different properties, pollution levels and ages

“…2). This is in agreement with previous studies (Wei et al 2016;Kulikowska et al 2015;Gusiatin and Radziemska 2018). With regard to most HMs (i.e., Zn, Ni, Cu), sequential soil washing with plant biosurfactants (SAP-SAP or TAN-TAN) removed more HMs than sequential soil washing with microbial biosurfactants (RAM-RAM).…”

Optimization of aeration enhanced surfactant soil washing for remediation of diesel-contaminated soils using response surface methodology

“…Five operating factors surfactant concentration, washing time, agitation speed, soil solution pH and airflow rate are selected and optimized. Soil properties like soil texture, organic matter content, mineral composition of the soil and pH significantly affect its contaminant desorption rate (Gusiatin & Radziemska, 2018). We also validate and compared the optimized operating factors under different soil textural classes, organic matter levels and age of contamination between aerated and non-aerated soil washing conditions.…”

Extraction of nonylphenol, pyrene and phenanthrene from sewage sludge and composted biosolids by cyclodextrins and rhamnolipids

“…PTEs content in the solution of the extractants (Table 3) showed that CDs have no statistically significant effect compared to water extraction capacity, whereas RL actually increased PTEs content on extracting solution significantly (Cr, Cu, Fe, Mn, Ni, Pb and Zn). No Journal Pre-proof J o u r n a l P r e -p r o o f extraction was detected for Cd, although RL has been described as a good extractant for Cd in contaminated soils (Gusiatin and Radziemska, 2018). The highest PTEs extractable contents were found for Fe > Mn > Ni > Zn, and the increases were especially notorious for Fe and Ni (around 10 and 50-fold higher respectively compared to water extraction).…”