Investigation on the removal of nitrate from water using different types of biosorbents

Eutrophication due to excessive leaching of dissolved nitrogen is a principal cause of water quality degradation. Among different types of removal methods, adsorption is contemporarily deemed favourable due to its simplicity, efficiency and reusability. In this study, six biosorbent candidates, namely rambutan skin (RS), passion fruit skin (PFS), longan seeds (LS), chia seeds (CS), papaya seeds (PS), and luffa (L) were investigated for nitrate removal from water at pH 3.0, room temperature, initial nitrate concentration of 50 mg/L, biosorbent particle size of 425 mu m, contact duration of 4 h, shaking speed of 120 rpm, and biosorbent dosage of 0.1 g. Shake flask method was carried out in the adsorption experiments to investigate the effect of heat treatment and acid treatment on the uptake of nitrate from water. The results showed that acid- and heat-treated passion fruit skin biosorbent (biochar, PFSBC) has the best biosorption performance for nitrate uptake of 5.179 mg/g. This biochar possessed high porosity, and abundant surface functional groups for nitrate adsorption.