Insights into adsorption of ammonium by biochar derived from low temperature pyrolysis of coffee husk

In the present work, coffee husk was used to produce biochar by pyrolysis process. Coffee husk was a typical agricultural residual in Vietnam. Therefore, biochar produced from coffee husk could be a cheap adsorbent which could be used to remove ammonium in water and wastewater. In this study, pyrolysis was carried out at low temperatures of 350 degrees C in a short time of 1 h. All experiments were carried out in batch tests. Coffee husk biochar produced at low pyrolysis temperatures without any activation process showed that the ability to absorb ammonium nitrogen was relatively high after 6 h with maximum 2.8 mg N/g biochar. Results confirmed that the sorption process of coffee husk biochar depended on adsorption phase exposure time between biochar and ammonium ion in the solution; pH of influent; initial concentration of ammonium; and solid/liquid ratio (biochar dose). Batch experiments also indicated that coffee husk biochar had average capacity to adsorb and partially removed certain amount of ammonium in real wastewater. In conclusion, coffee husk biochar produced from low temperature pyrolysis could substitute high-priced commercial adsorbent to treat ammonium from different water and wastewater sources.

Automated summary

This study produced biochar from coffee husk and found that it had a high adsorption capacity for ammonium. The adsorption process of coffee husk biochar was influenced by factors such as contact time, pH, ammonium concentration, and solid/liquid ratio. Batch experiments also confirmed the ability of coffee husk biochar to partially remove ammonium from wastewater.