Impact of natural and calcined starfish (Asterina pectinifera) on the stabilization of Pb, Zn and As in contaminated agricultural soil

Abstract

Metal stabilization using soil amendments is an extensively applied, economically viable and environmentally friendly remediation technique. The stabilization of Pb, Zn and As in contaminated soils was evaluated using natural starfish (NSF) and calcined starfish (CSF) wastes at different application rates (0, 2.5, 5.0 and 10.0 wt%). An incubation study was conducted over 14 months, and the efficiency of stabilization for Pb, Zn and As in soil was evaluated by the toxicity characteristic leaching procedure (TCLP) test. The TCLP-extractable Pb was reduced by 76.3-100 and 91.2-100 % in soil treated with NSF and CSF, respectively. The TCLP-extractable Zn was also reduced by 89.8-100 and 93.2-100 % in soil treated with NSF and CSF, respectively. These reductions could be associated with the increased metal adsorption and the formation of insoluble metal precipitates due to increased soil pH following application of the amendments. However, the TCLP-extractable As was increased in the soil treated with NSF, possibly due to the competitive adsorption of phosphorous. In contrast, the TCLP-extractable As in the 10 % CSF treatment was not detectable because insoluble Ca-As compounds might be formed at high pH values. Thermodynamic modeling by visual MINTEQ predicted the formation of ettringite (CaAl(SO)(OH)·26HO) and portlandite (Ca(OH)) in the 10 % CSF-treated soil, while SEM-EDS analysis confirmed the needle-like structure of ettringite in which Pb was incorporated and stabilized in the 10 % CSF treatment.

Slow pyrolyzed biochars from crop residues for soil metal(loid) immobilization and microbial community abundance in contaminated agricultural soils

“…PO 4 3is chemically analogous to As(V); hence, the increase in PO 4 3induces the release of As from the soil colloids to the soil solution (Ahmad et al, 2016c;Beesley et al, 2014;Lim et al, 2016). This might be a reason for the highest exchangeable As observed when WB was added to the U-soil.…”

Assessment of the Stabilization of Cu-, Pb-, and Zn-Contaminated Fine Soil Using Cockle Shells, Scallop Shells, and Starfish

“…In this study, SEM-EDX was used to identify the effective heavy metal stabilization mechanisms in contaminated soil according to the addition of stabilizing agents. SEM-EDX analysis is mainly used to identify stabilization mechanisms since it can examine the images and constituent elements of the stabilized material [27][28][29][30][31][32]. Samples containing 10 wt% of CCKS10, CSLS10, and CASF10 were compared to the contaminated soil, which exhibited the highest stabilization efficiency, and selected as target samples.…”

Microscopic Mechanism of Cement Improving the Strength of Lime‐Fly Ash‐Stabilized Yellow River Alluvial Silt

“…e macroscopic mechanical properties of soil essentially depend on its microstructure, so studying soil microstructure characteristics helps to better understand the mechanism of strength improvement [34,35]. Some scholars have used different microscopic methods to study the microstructure characteristics of soil or stabilized soil, including scanning electron microscopy (SEM) [36][37][38][39][40], mercury intrusion porosimetry (MIP) [41][42][43], energy dispersive X-ray spectroscopy (EDS) [44][45][46], and X-ray diffraction [25,47]. Using microscopic technology to study soil microscopic properties has become quite popular and mature.…”