Sequential removal of chromium (VI) and prednisolone by nanobiochar- enriched-diamine derivative

Abstract

Biochars are biosorbents made from a wide range of agricultural or animal residues that involve functional groups to enable binding with different species. In the current work, pyrolysis of artichoke leaves was done to generate nanobiochar (NanoBch) and enriched with ethylenediamine (EDA) as nitrogen-rich derivative to yield (NanoBch-EDA). This was characterized by different techniques and compared with NanoBch. The evaluated NanoBch-EDA showed promising removal performance under optimized conditions of contact time, nanosorbent dosage, initial concentration of Pn and Cr(VI), pH, temperature, and interfering ions. The elimination processes of Pn and Cr(VI) onto (NanoBch-EDA) by four isotherm models (Langmuir, Dubinin-Radushkevitch, Temkin, and Freundlich) were discussed. In Pn elimination process, the Langmuir model achieved (R2 = 0.99) as the highest correlation coefficient. Otherwise, the Freundlich (R2 = 0.98) was the applicable model in Cr(VI) elimination. The values of maximum capacity qmax (mg g−1) for adsorption of Pn and Cr(VI) onto NanoBch-EDA were 21.93 and 79.37 mg g−1, respectively. Based on the obtained R2 (0.999), the pseudo-second-order model was shown to be the superlative match for describing the elimination of Pn and Cr(VI) by NanoBch-EDA. The reaction was stated as spontaneous and endothermic based on parameters signs and values obtained from thermodynamic studies. NanoBch-EDA (60 mg) was found highly effective in extracting 95.0%, 90.0%, and 92.0% of Pn (25 mg L−1) from tap, waste, and sea water, respectively, while 20 mg of NanoBch-EDA removed 96.0%, 94.6%, and 97.3% of Cr(VI) 10 mg L−1 from tap, waste, and sea water, respectively.