Abstract
Corn stalk was used as the initial material to prepare a corn stalk matrix-g-polyacrylonitrile-based adsorbent. At first, the corn stalk was treated with potassium hydroxide and nitric acid to obtain the corn stalk-based cellulose (CS), and then the CS was modified by 2-bromoisobutyrylbromide (2-BiBBr) to prepare a macroinitiator. After that, polyacrylonitrile (PAN) was grafted onto the macroinitiator by single-electron transfer living radical polymerization (SET-LRP). A novel adsorbent AO CS-g-PAN was, therefore, obtained by introducing amidoxime groups onto the CS-g-PAN with hydroxylamine hydrochloride (NH2OH · HCl). FTIR, SEM and XPS were applied to characterize the structure of AO CS-g-PAN. The adsorbent was then employed to remove Pb(II) and Cu(II), and it exhibited a predominant adsorption performance on Pb(II) and Cu(II). The effect of parameters, such as temperature, adsorption time, pH and the initial concentration of metal ions on adsorption capacity, were examined in detail during its application. Results suggest that the maximum adsorption capacity of Pb(II) and Cu(II) was 231.84 mg g–1 and 94.72 mg g−1, and the corresponding removal efficiency was 72.03% and 63%, respectively. The pseudo-second order model was more suitable to depict the adsorption process. And the adsorption isotherm of Cu(II) accorded with the Langmuir model, while the Pb(II) conformed better to the Freundlich isotherm model.
Highlights
Heavy metal ions have received considerable concern as the main source of the aquatic environmental pollution due to their high toxicity and non-biodegradable [1,2]
A new band emerged at 2242 cm−1 after grafting, which was attributed to the vibration of cyano groups confirmed the success of graft polymerization
A small surface area and almost low porosity are characteristics of natural polymer materials, such as cellulose and chitosan, but they have been used as adsorbents in the literature because of their low cost and wide availability, and the results show that their performance in metal ions removal is satisfactory [40,44]
Summary
Heavy metal ions have received considerable concern as the main source of the aquatic environmental pollution due to their high toxicity and non-biodegradable [1,2]. A tremendous amount of effort has been made to develop technologies for removal of heavy metal ions from wastewater, such as reverse osmosis chemical precipitation, photocatalysis technology, adsorption and membrane filtration [6,7,8,9]. Among all these technologies, adsorption is predominant in the sewage disposal process because of its great performance in energy saving and high efficiency [10]. A large number of attempts have been made to develop comparatively cheap materials to prepare low-cost adsorbents [12,13,14]. A wide variety of crop residue including wheat straw [18,19], sweet potato starch [20,21], sunflower leaves [22] and water bamboo husk [23] have been used as raw materials for the adsorbent
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