The application of protic ionic liquids (PILs) proved to be a viable and sustainable method for chitin extraction from shrimp shell biomass waste. Among the three amin-based PILs investigated for extracting chitin from shrimp shells (Triethylammonium acetate TeaAc, Triethylenetetrammonium acetate TetaAc, and Ethanolammonium acetate EthAc), EthAc was selected as the optimum option due to its greener characteristics, lower toxicity, biodegradability, and property enhancement. The PIL-extracted chitosan was then used as a biosorbent for the selective adsorption of Co(II), Mn(II), and Ni(II) from the leachate of spent lithium-ion battery (LIB) cathodes, leached with a synergistic mixture of 1.25 M sulfuric acid and 0.55 M citric acid. Chitin extraction parameters (temperature, time, and liquid-to-solid ratio) were optimized using response surface methodology. The optimal conditions (92 °C, 27.8 h, L/S = 16 g/g) resulted in a chitin yield of 56.67 wt.%, with adsorption rates of 82.42 ± 1.65% for Co(II), 35.09 ± 2.63% for Mn(II), and 98.30 ± 0.63% for Ni(II). Adsorption isotherm analysis of the optimal Eth-extracted chitosan demonstrated adsorption performance exceeding that of commercial chitosan. FT-IR spectra matched those of commercial chitosan, confirming the preservation of key functional groups, whereas BET analysis indicated a higher specific surface area. Collectively, these results validate a green, waste-biomass-derived adsorbent for the efficient recovery of critical metals from spent lithium-ion batteries while simultaneously valorizing biomass waste. • Ammonium-based ionic liquids were used to extract chitin from shrimp shell waste. • Shrimp shell-derived chitosan treated spent LIBs in a circular economy approach. • Eth-extracted chitosan was used as a biosorbent for critical metal recovery. • Optimal extraction chitin conditions were 92 °C, 27.8 h, L/S = 16 g/g. • The adsorption rates were 82% for Co(II), 35% for Mn(II), and 98% for Ni(II).
Roshanfar et al. (Wed,) studied this question.