![zn xps peak zn xps peak](https://www.researchgate.net/profile/Metwally-Madkour/publication/290508883/figure/fig2/AS:328623664975873@1455361395399/PS-peaks-for-Zn-2p-and-S-2p.png)
Heavy metals are toxic, transportable and nonbiodegradable, and can accumulate in organisms and even humans, seriously threatening human health and environmental safety. L −1 according to the Comprehensive Wastewater Discharge Standard (GB8978-1996, China).In China, the maximum allowable discharge level of copper, manganese and zinc is 5.0 mg In particular, heavy metal pollution, as a byproduct of rapid economic development, is widely encountered in many industrial wastewaters, as in nonferrous metal smelting, the electroplating industry, and in tailings. In recent years, due to the acceleration of industrialization and urbanization, environmental pollution has become increasingly serious. The results revealed that ion exchange was likely crucial in Mn(II) and Zn(II) removal, while C-O, O-H and C = O possibly were key to Cu(II) removal by complexing or other reactions. Moreover, characterization analysis was performed using Fourier transform infrared spectroscopy, the Brunauer-Emmett-Teller method, scanning electron microscopy with energy-dispersive X-ray spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The results showed that the chemical adsorption of single molecules was the main heavy metal removal mechanism. The isotherm data demonstrated the Langmuir model fit for Zn(II), Mn(II) and Cu(II). The adsorption kinetics of all three metal ions followed the pseudo-second-order kinetic equation. Compared to Mn(II) and Zn(II), the biochar exhibited highly selective Cu(II) adsorption. Adsorption experiments showed that the initial solution pH affected the ability of the biochar to adsorb heavy metal ions in single- and polymetal systems.
![zn xps peak zn xps peak](https://sales.xpssimplified.com/_images/element-oxygen-xpsspectra2.png)
Low-cost banana stalk ( Musa nana Lour.) biochar was prepared using oxygen-limited pyrolysis (at 500 ☌ and used), to remove heavy metal ions (including Zn(II), Mn(II) and Cu(II)) from aqueous solution.