Adsorption of Cu (II) and Ni (II) from aqueous solutions by taro stalks chemically modified with diethylenetriamine

Abstract

Taro stalks (TS) were modified by diethylenetriamine (DETA) to obtain the modified taro stalks adsorbents (recorded as MTSA). This kind of raw material is unprecedented and the method of modification is relatively simple. The physicochemical properties of MTSA were characterized by scanning electron microscope (SEM), FTIR, and zeta potential analyzer. The capacity of MTSA for adsorbing heavy metals under different influencing factors was tested by UV-visible spectrophotometer. The results indicated that the gaps between the microspheres of MTSA are more, which are conducive to adsorption. The MTSA might have increased the amino-functional groups which are beneficial for adsorption, resulting in an increase in the adsorption capacity of copper and nickel ions (35.71 and 31.06 mg/g) of about 5–7 times compared to bare taro stalks (5.27 mg/g and 6.08 mg/g). High Cu²⁺ uptake on MTSA was observed over the pH range of 5.5–7.0, while for Ni²⁺ the range was 7.0–8.5, and the optimum dosage of adsorbent were both about 0.80 g for Cu²⁺ and Ni²⁺. The adsorption kinetics of Cu²⁺ and Ni²⁺ on MTSA could be interpreted with a pseudo-second order and the equilibrium data were best described by the Langmuir isotherm model.

Graphical abstract

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