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Mg-Modified Sugarcane Bagasse Biochar for Dual Removal of Ammonium and Phosphate Ions from Aqueous Solutions

Maher E. Saleh and Ramzy M. R. Hedia

Utilization of agricultural wastes to generate cheap and efficient sorbents to remove contaminants from wastewaters is an up-to-date environmental challenge. In Egypt, sugarcane bagasse is yearly generated as a waste material in huge amounts. The objectives of this study were to investigate the effect of chemical modification on the properties of bagasse biochar generated from local sugarcane bagasse feedstock (SCBF) and assess its efficiency for removal of both ammonium and phosphate ions from artificial aqueous solutions. SCBB and Mg-SCBB biochars were produced through pyrolysis of raw SCBF and MgSO4 impregnated SCBF, respectively at 500 ◦C and under oxygen-limited condition. FTIR peaks analysis, DEM examination, and some physical and chemical properties revealed that new surface functional groups, meso- and micropores, larger surface area and higher CEC were developed in SCBB and Mg-SCBB compared to SCBF. SCBB and Mg-SCBB showed high affinity to ammonium adsorption from aqueous solutions comparable to Charcoal and Zeolite. Mg-SCBB was the only sorbent capable of removing phosphate from the aqueous. Ammonium and phosphate removal at 1:200 sorbent to solution ratio were higher than those at 1:500 for all sorbents. A slight ammonium volatilization occurred during the adsorption process due to high solution pH. Adsorption kinetics data were best fitted to the pseudo-second-order kinetic equation suggesting intraparticle diffusion controlled adsorption process. Ammonium adsorption isotherms were best fitted to Freundlich model. The calculated Freundlich intensity parameter (n) ranged from 0.478 to 0.894 indicating favorable adsorption of ammonium and phosphate by all sorbents. Mg-SCBB had an adsorption capacity of 2573.9 and 4002.2 mg kg-1 for ammonium and phosphate, respectively. The produced Mg-modified sugarcane bagasse biochar may represent a promising efficient and cheap sorbent for dual remediation of wastewaters contaminated with ammonium and phosphate ions.

 

Keywords: Sugarcane bagasse, Mg-modified biochar, ammonium and phosphate removal, agricultural wastes, aqueous solutions.