Synthesis of novel diol modified chitosan and their enhanced selective adsorption behavior for germanium(Ⅳ)

Germanium (Ge) is an important semiconductor material, and its effective extraction and recovery is turning into progressively vital. However, high efficient recovery of Ge(IV) via convenient approach is remaining a challenge. Herein, an efficient adsorbent (HEMA-IDOI-CS) was prepared for recovering of Ge(IV) by grafting poly(hydroxyethyl methacrylate) (HEMA) and 3-chloro-1,2-propanediol onto chitosan (CS). The steric effect of the o-hydroxyl groups is highly desirable to selectively chelate with tetrahedral Ge(IV), which greatly enhanced the efficiency of the CS-based materials. HEMA-IDOI-CS exhibited excellent adsorption performance at pH 3–8. The maximum capacity was 73.91 mg g−1 at pH 4, and the efficiency reached 99.26% at pH 4–6. In addition, HEMA-IDOI-CS exhibited good selectivity for Ge(Ⅳ) in the presence of Zn(II), Cu(II), Mn(II), Pb(II), As(III) and Fe(III). The kinetic data was well fitted with the pseudo-second-order kinetic model and the adsorption behavior is consistent with the Langmuir adsorption isotherm model. Moreover, the recovery rate of the adsorbent preserved 95% after four adsorption-elution cycles, demonstrating its good reusability. The adsorption performance of HEMA-IDOI-CS for Ge(Ⅳ) is much better than that of a lot other adsorbents previously reported.