Adsorption of Pb(II) by montmorillonite modified biochars and reduction Pb(II)-stress in plants of microcosms of constructed wetlands: mechanism and treatment performances
Yaohong Zhang, Renrong Liu, Liya Tan, Ningcan Yang, Anna Kerkula, Hai Wang
Abstract
ABSTRACT In the study, the peanut shell was selected as original biochar and modified by adding montmorillonite to obtain modified biochar (B@M). The adsorbent was characterized by scanning electron microscopy, Brunauer–Emmett–Teller, Fourier-transform infrared spectroscopy and X-ray diffraction. The adsorption kinetics study of Pb(II) on B@M showed that the adsorption process of Pb(II) was according to the pseudo-second-order model and Langmuir adsorption model. The maximum adsorption capacity of B@M (61.5 mg g –1 ) was significantly higher than that of the biochar (35.5 mg g –1 ) and montmorillonite (54.4 mg g –1 ) and the reproducibility study indicated that B@M had good reproducibility. When the B@M was added to the microcosms of constructed wetlands (MCW), it showed that with the increase of the amount of B@M, the removal rate of lead in water increased significantly, which was 31.3%, 48.3% and 86.1%, respectively and can reduce the stress of Pb(II) in plants of MCW. Therefore, B@M can be used as a new substrate material and heavy metal Pb(II) adsorbent for constructed wetlands.