Assessment of interactive effects of sophorolipids and pine needle biochar augmentation in the process of phytoremediation of Cd contaminated soil using response surface methodology

In present study, response surface methodology (RSM) based central composite design (CCD) was used to study the interactive effect between two individual soil amendments, sophorolipids (SLs) and pine needle biochar for the phytoremediation of Cd contamination and enzymatic activity of soil. The experimented concentrations of SLs and biochar ranged from 0.5 to 2.6 g/kg and 0.4–1.8 %, respectively. The SLs and biochar at the concentration 1.1 g/kg and 1.55 % respectively exhibit the maximum uptake in shoot (125.33 mg/kg) and root (298.27 mg/kg). The results also showed higher R² (>0.9) for Cd uptake in B. pilosa and R² (>0.85) for soil enzymatic activity using model generated by CCD of RSM. These results signify the reliability of the model and suggested that this model could be used for the prediction of increased metal uptake by plants. The optimum concentrations of SLs and biochar predicted by the CCD were 1.23 g/kg and 1.55 %, respectively with desirability score of 1 for the uptake of Cd in B. pilosa. The results highlighted that application of these amendments can be a pivotal step in the direction of remediation of heavy metal contamination from soil at larger scale.