The effect of Pyrolysis Temperature and Type of Organic Residues on Physicochemical Properties of Produced Biochar

Biochar has attracted the attention of many researchers because of its ability to improve soil fertility, immobilization of pollutants, as well as a suitable method of carbon sequestration and as a carbon reservoir. In order to investigate the effect of pyrolysis temperature and type of organic residues on physicochemical properties of biochars, a completely randomized designe as a factorial experiment was designed with two factors of organic residues type (wheat straw and walnut and almond bark) and pyrolysis temperature (300 and 500°C) in three replicates. The results showed that EC, pH, ash, and CEC of biochar increased at pyrolysis temperature of 300°C. By increasing the pyrolysis temperature to 500°C, the amount of organic carbon (OC), CEC, and surface functional groups of biochar decreased compared to biochar produced at 300 °C whereas pH, ash, and EC increased. The highest EC, pH, water soluble materials, ash, and the lowest bulk density were recorded in wheat straw biochar produced at 500°C. The highest value of equivalent calcium carbonate was obtained in almond peel biochar produced at 500°C. Biochar production yield decreased and the loss of volatile compound such as CO2 increased by increasing the pyrolysis temperature from 300°C to 500°C. In addition, the characteristics of biochar were dependent on type of feedstock and pyrolysis conditions (temperature and time residence).