Nitrate (NO₃-) and chromium (Cr(VI)) ions from contaminated aqueous solutions were successfully adsorbed onto functionalized cocoa shell (ECAB, an agricultural waste material) via chemical grafting of 3-aminopropyltriethoxysilane (APTES). The resulting adsorbent – ECAB-APTES-HCl – was characterized by SEM, zeta potential, calorimetry, FTIR spectroscopy and point of zero charge. The adsorption parameters were investigated to optimize the removal of chromium and nitrate ions. The maximum removal efficiency stabilized at around 91-99% for chromium and 58% for nitrate, for an initial concentration of 50 mg.L⁻¹ of the ions. The adsorption process fitted well with both Freundlich and Langmuir isotherms, and with the pseudo-second order model. Accordingly, adsorption onto ECAB-APTES-HCl involved both physisorption and chemisorption. Desorption studies demonstrated that 82% of nitrate and 79.8% of chromium were recovered in less than 2 hours. These results open onto the possible removal of heavy metals from aqueous solutions in the absence of energy constraints, using low-cost biomass relevantly functionalized for high adsorption efficiency.

通过3-氨基丙基三乙氧基硅烷（APTES）的化学接枝，将受污染水溶液中的硝酸根（NO _3-）和铬（Cr（VI））离子成功吸附到功能化可可壳（ECAB，一种农业废料）上。所得吸附剂ECAB-APTES-HCl通过SEM，ζ电位，量热法，FTIR光谱和零电荷点进行了表征。研究了吸附参数以优化铬和硝酸根离子的去除。初始浓度为50 mg.L ^-1时，最大去除效率稳定在铬的91-99％和硝酸盐的58％左右。离子。吸附过程与Freundlich等温线和Langmuir等温线以及拟二阶模型都非常吻合。因此，在ECAB-APTES-HCl上的吸附涉及物理吸附和化学吸附。解吸研究表明，在不到2小时的时间内回收了82％的硝酸盐和79.8％的铬。这些结果表明，在没有能量限制的情况下，可以使用功能相关的低成本生物质实现高吸附效率，从而从水溶液中去除重金属。