Characteristics of biochars derived from fruit tree pruning wastes and their effects on lead adsorption

The aim of this study was to evaluate the biochar characteristics derived from fruit tree pruning wastes (FTPW) and their effects on lead (Pb) adsorption. Based on results from Pb adsorption, surface area, and phosphorus content, the optimum pyrolysis temperature was 600 °C for Pb adsorption capacity. Using the Freundlich isotherm, the Pb adsorption capacity (K) of biochar obtained from various FTPW decreased in the order of pear (3.8001) ≫ persimmon (2.3977) ≥ apple (2.1968). Based on the Langmuir adsorption isotherm, the maximum Pb adsorption capacities (a; mg g−1) of biochar obtained from different FTPW were in the following order: pear (26.2) ≫ persimmon (19.9) ≥ apple (17.7). The maximum Pb adsorption capacity of the pruned pear tree waste biochar was greater than the other FTPW biochars. Pruned apple tree waste biochar had the lowest Pb adsorption capacity among the tested FTPW biochars. The positive correlation between the Langmuir maximum adsorption capacity (LM) values of the biochars and their phosphorus content and surface area indicated difference in adsorption capacity. However, adsorption capacity of the biochar from all FTPW studied could be used for removing Pb and other metal from wastewater.