In this study, biochar (BC) derived from slow pyrolysis of spruce sawdust and activated BC with HNO3 were used as sorbents to remove methylene blue (MB) dye from the aqueous solution. BC was prepared by pyrolysis at temperatures of 200, 300, 400, and 500 °C. Based on the screening results, the two BCs (BC prepared at 400 °C and BC prepared at 500 °C) exhibiting a higher percentage of dye removal were selected to investigate further the effect of factors, including contact times 15, 30, and 60 minutes and the amount of dosage – BC 0.01, 0.03, 0.05 g / 8 mL. The sorption efficiency of MB was determined by measuring the absorbance of the solutions after sorption in a UV / VIS area of 665 nm. BC prepared at 500 °C was found to perform better than BC prepared at 400 °C and activated BC by HNO3 and has more than 95 % rate of methylene dye adsorption.
Science Journal 