Ammonium-nitrogen removal from aqueous solution using municipal green waste wood biochars

Ammonium (NH۴+), one of the most common types of reactive form of nitrogen in wastewater, can cause eutrophication and other environmental problems if released into waterways. This study was conducted to understand NH۴+ adsorption mechanism of wood biochar from municipal green waste in an aqueous environment and the factors affecting NH۴+ removal. The biochars were produced by pyrolyzing green wood waste at ۳۰۰°C (WB۳۰۰), ۴۵۰°C (WB۴۰۰), and ۶۰۰°C (WB۶۰۰), respectively. Biochar dosage, pH, and contact duration were studied during NH۴+ adsorption studies to see how these variables affected the adsorption process. The adsorption process was studied using isotherms and kinetic adsorption models. The batch equilibrium and kinetic studies at ۲۵°C, pH ۷, and a contact duration of ۲۴۰ minutes showed that the WB۴۵۰ dosage of ۰.۲ g/L removed the most (NH۴+-N) compared to WB۶۰۰ and WB۳۰۰. WB۴۵۰ had higher affinity values and a maximum adsorption capacity of ۲.۳۴ mg/g; the ‘Freundlich isotherm’ model had a better fit to the equilibrium experimental data, indicating that heterogeneous sorption was preferable to monolayer sorption. Chemisorption was the dominant (NH۴+) adsorption method, as demonstrated by the ‘pseudo-second-order’ kinetic model with an R۲ of ۰.۹۹. The study concludes that municipal green wood waste-based biochar can be efficient absorbents for NH۴+ removal from wastewater. Also, the removal efficiency can be optimized by selecting different feedstocks or the pyrolysis condition for biochar production.

کلیدواژه ها:

ammonium nitrogen ، adsorption process. municipal green waste ، slow pyrolysis ، wood biochar