Nutrient pollution, a major global environmental threat, is one of the most important research issues to address. In this regard, this research paper aims to valorization of date stones (DS), which have been physically activated by pyrolysis to obtain biochar (BDS), and chemically modified with magnesium (Mg-BDS), to synthesize an composite adsorbent capable of efficiently adsorbing nitrate. The prepared adsorbent was characterized using FTIR, XRD, SEM, EDX, and pH PZC , which showed that Mg-BDS was successfully modified to become a highly porous adsorbent. The adsorption efficiency reached 90.5% and the maximum adsorption capacity of the Langmuir model was 29.54 mg/g. The adsorption data were best described by the pseudo-second-order kinetic model and Freundlich isotherm. Thus, that the adsorption process of nitrate on Mg-BDS is a multi-layer physical and chemical mechanism including: intraparticle diffusion, surface physical adsorption, electrostatic adsorption and ion exchange. Thermodynamics analysis indicate that the adsorption process are exothermic. The Mg-BDS was reused to reach its capacity of 6 cycles. To verify the real performance of Mg-BDS in nitrate adsorption, it was applied to real wastewater (domestic wastewater of Biskra city (Oued Z’mor) located in southern Algeria), where the nitrate adsorption efficiency was estimated at 72.28%, in addition to removing other pollutants.
Djezzar et al. (Sat,) studied this question.