Formation of self-nitrogen-doping activated carbon from Fish/sawdust/ZnCl2 by hydrothermal and pyrolysis for toxic chromium adsorption from wastewater

Abstract

This study gives a description of the formation of self-nitrogen doped activated carbon (NDAC) by a novel way of employing fish meal (mixture of Atherina hepseetus and Sardina pilchardus of 60% protein) as nitrogen dopant, ZnCl2 as impregnate agent, sawdust as carbon source and water with a mass ratio (2:1:1:12), which subjected to the hydrothermal process. The hydrothermal mixture was oven dried and carbonized under a flow of nitrogen for one h at 600, 700, and 800 °C. The characterization of NDAC was performed by using various analytical techniques analyses. The synthesized NDAC exhibited unique features such as microporous structure (1.84 ~ 2.01 nm), high surface area (437.51 ~ 680.86 m2/g), the volume of total pores (0.22 ~ 0.32 cm3/g) and nitrogen content (12.82 ~ 13.73%). Batch removal tests were achieved to investigate the impact of chromium ions starting concentration (100–400 mg/L), NDAC dose (0.5–2.5 g/L), pH and contact time (5–120 min). Such helpful characteristics of NDAC, particularly for NDAC600, were suitable to use as an excellent adsorbent for Cr6+ ions with a maximum adsorption capacity (Qm) (769.23 mg/g), and the highest chromium ions adsorption uptake (81.18%) was obtained at pH value 1.5 at room temperature. Both Halsey and Temkin models fitted the adsorption data quite reasonably. The uptake of toxic chromium ions is best represented with pseudo-second-order rate kinetics data.

Enhancing Cd²⁺ Removal from Aqueous Solution: ZnCl₂-Modified Citrus Peel Carbon Optimization via Box-Behnken Response Surface Methodology

“…While the sharp absorption at 2881-2829 cm −1 represents C-H vibrations for methyl groups [23]. Further the -C≡N was also confirmed by the significant absorption at 2359 cm -1 for isonitrile cyano terminal groups [24]. Similarly, absorption peaks at 1795, 1579 and 1431 cm -1 corresponds to ν(C=O) vibration in lactones, ketones and carboxylic anhydrides;…”

ZnO@ activated carbon derived from wood sawdust as adsorbent for removal of methyl red and methyl orange from aqueous solutions

“…Accordingly, the estimated pH PZC values are 2 and 7.5 for the AC and the ZnO@AC composite, respectively. At pH values below pH PZC , the surfaces of the AC and ZnO@AC composite were positive, while at pH values above pH PZC , the surfaces were negative 34 .…”

Effect of synthesis conditions on the porous texture of activated carbons obtained from Tara Rubber by FeCl3 activation

“…Chemical activation can, by analogy with physical activation, be a one-step process or a two-step process preceded by carbonisation in the case of obtaining activated carbons from biomass by chemical activation using NaOH or KOH as activator 27 – 37 , as otherwise these strong bases may dissolve the organic matter of the precursor, making subsequent activation impossible. Compared to physical activation, chemical activation allows better development of surfaces and microporous structures and is less energy-intensive due to the lower process temperature and its shorter time 38 , 39 . Chemical activation, however, requires an additional washing process of the final product to remove residues of the activator used.…”