Synthesis and Characterization of Novel Biochar Developed from Peganum Harmala Seeds to Adsorb Heavy Metals from Aqueous Solution.

Referring to the oil and industrial development, contamination of water streams and soil by heavy metals becomes severe issue. Biochar has consider as cheap and ecofriendly adsorbent for heavy metal ions removal. As well as, the development and modification of biochar has been a center point of many researches. In this study it has been suggested to develop novel biochar from Peganum harmala seed precursor and evaluate the heavy metal ions adsorption performance. Chemical activation process was adopted to prepare biochar with different concentrations (20%, 30%, and 40%) of phosphoric acid followed by pyrolysis in a laboratory horizontally tube furnace underneath an N₂ blanket at 600 ℃ for 3 hours. The physical and chemical properties of biochar have been assessed using Energy Dispersive X-ray Spectroscopy, X-ray diffraction, Scanning Electron Microscopy, pore structure, and Fouriertransform analysis. The prepared biochar was investigated to absorb three different heavy metal ions Fe(III), Ni(II) and Pb(II) from an aqueous solution under varied conditions. Heavy metal concentration (20-100 ppm), adsorbent dosage (0.25-0.75) g/L, contact duration (0-560 min), and solution pH (2-9) were examined. The results show that the largest BET surface area (691.58 m²/g) was achieved with activation conversation of 40% H₃PO₄ and 600 ℃ for 3 hours, compared to other samples. The maximum adsorption capacities were 113.4096, 112.3355, 180.3478 mg/g for Fe(III), Ni(II) and Pb(II) respectively. Finally, Freundlich isotherm model shows better describe the adsorption equilibrium data, while adsorption kinetic data shows the pseudo-first-order model fits more with Fe(III) ions which shows that chemisorption was controlled in the adsorption process, additionally the pseudo-first-order model fits more with Pb(II) and Ni(II) ions this mean the physisorption has been controlled in the adsorption process. [ABSTRACT FROM AUTHOR]