Pb (II) removal from aqueous solution by biochar produced from giant reed
Creators: name: YORK, Eric
Publisher: name: RMIT University
Year: 2024
Subjects: classificationCode: 419999
subject: Other environmental sciences not elsewhere classified

description: The presence of lead, a trace element in the environment, has been a serious concern especially with rapid urbanization, which has increased its concentration in the environment by several hundred fold. The toxicity of this trace metal to aquatic life and humans has necessitated the development of effective and economical methods for the treatment of water.  

Biochar has garnered attention as a means to sequester carbon and manage waste in the environment, particularly in soil and water. Invasive biomass such as the giant reed is rich in lignin and the conversion of this biomass into char for environmental restoration is a prime area for further research.  

The main aim of this investigation was to develop a low-cost solution to remove trace metals from the aqueous phase using biochar. This study investigated (i) the effect of giant reed-based biochar produced at varying temperatures in the treatment of aqueous solutions polluted with lead; and (ii) how the production of biochar at different temperatures affected its adsorption capacity for lead from the aqueous phase. 

The sorption of Pb (II) by biochar produced from giant reed at different temperature profiles was studied. Two biochars, produced at a temperature of either 300 degree celsius or 500 degree celsius, were studied. The prepared biochars were characterized using the following: an X-Ray Diffractometer; BET Surface Area and Pore Analyser; Scanning Electron Microscope; Carbon, Hydrogen &amp; Nitrogen Analyser;13C Nuclear Magnetic Resonance Spectrometer; and Thermogravimetry Analyser. 

The results showed that biochar produced at 300 degree celsius was more effective than that produced at 500 degree celsius in the removal of lead from aqueous solution. Solution pH showed a strong effect on the adsorption ability of giant reed biochar produced at 300 degree celsius (GR 300 degree celsius) to adsorb Pb (II) ions. The maximum adsorption capacity (19.2 mg/g) was found to occur under the following conditions: Temp. 25 degree celsius , Pb (II) conc. 40 mg/L, stirring rate 60 rpm, biochar dosage 0.1g / 100 mL, 24 h. The equilibrium data were fitted to Freundlich and Langmuir models. The Freundlich Isotherm gave the best fit for GR 300 degree celsius with a value of 0.88. FTIR analysis and batch experiments results suggested that Pb (II) adsorption mechanisms were dominated by complexation with active surface groups, precipitation and cationic exchange. Experimental model results suggested that giant reed- derived biochar has a good adsorption capacity for Pb (II) in aqueous solution compared to other plant biochars reported in the literature. 

The application of biochar in remediation of ground waste water is still warranted and future research should consider that the outcome of remediation of ground waste water could be achieved with biochar. Under a holistic approach to assessing remediation options, the environmental outcome of the application of giant reed biochar will help equip researchers and industry alike in their endeavour to reduce the burden posed by contaminated groundwater into the future.