Different Biochars Production and Their Effect on Removal of Cd (II), Ni (II) and Pb(II) from Irrigation water

Today, hazard of surface and underground water contamination with heavy metals has led to a global concern. Therefore, the current study was carried out to assess the effects of different types and rates of biochar on irrigation water heavy metals content.

For this purpose, 12 different biochars were produced using 6 different biomasses including wheat stubble, pea stubble, maize residual, reed stem and leaves, olive meal and beet pulp at 500 and 700 C under low oxygen condition. According to specific area results, cation exchange capacity and infrared spectrophotometry, wheat stubble, reed stem and leaves and residual maize biochars, which produced at 700 °C were selected for further studies. Then effect of nine levels of these biochars on irrigation water heavy metals (cadmium, nickel and lead) content were investigated using a completely randomized design(CRD) with three replicates. 

The results indicated that increase in temperature significantly reduce biochars yield, volatile compound percentage but increase acidity, cation exchange capacity, specific area and ash percentage. In addition, the results revealed that biochars and their applied doses could significantly reduce heavy metals content in irrigation water.

Increase in specific area, cation exchange capacity and acidity led to heavy metals elimination from irrigation water. Application of MB700 (compared with WB700 and RB700) and WB700 (compared with MB700 and RB700) could significantly reduce cadmium and nickel, respectively, whereas the effect of MB700 and WB700 in eliminating of lead was more pronounced than RB700. The maximum cadmium, lead and Nickel reduction was related to apply 32 g per liter biochar.