Kinetics and Adsorption Isotherm of Strontium on Sugarcane Biochar and Its Application in Polluted Soil

Abstract

Removal of inorganic soil pollutants (e.g. Sr2+) is considered necessary requirement to protect the environment and public health. So sugarcane bagasse biochar (SCBB) was examined as a biosorbent material for Sr2+. This was done through adsorption Stirred-batch technique including a kinetic experiment, at two concentrations (50 and 150 mg/l) and an adsorption isotherm experiment at five concentrations (20, 50, 100, 150, and 200 mg/l), by using SrCl2·6H2O. Moreover, an examination of the role of SCBB at three dosages (0.5, 1, 2%w/w) in reducing the bioavailability of strontium in polluted soil through pots experiment by using Raphanus sativus. Kinetic data revealed that equilibration time was 3 h and pseudo-second-order model was more represented in data at low and high concentrations where (R2 = 0.999 and R2 = 1), respectively. Thus, chemisorption governed the adsorption process for Sr2+removal by SCBB. Furthermore, Langmuir isotherm model (R2 = 0.99) described the adsorption data better, which indicated that a monolayer type of adsorption plays a vital role in the removal of Sr2+ by SCBB. Pots experiment revealed that SCBB could significantly reduce Sr2+ uptake by Raphanus sativus. The percentages of decrease in the shoot were 5.82, 18.17, and 26.80% for SCBB dosage 0.5, 1 and 2% w/w, respectively. The percentages of decrease in root were 17.20, 36.89, and 53.34% for SCBB dosage 0.5, 1 and 2% w/w, respectively. Specific surface area and surface functional groups of sugarcane bagasse play a vital role in the retention of strontium. Hence, biochar played an important role in the removal of Sr2+ from aqueous solution and reduced its uptake by plants in soil.