Abstract
This study is aimed to investigate the effect of raw and Fe-modified coconut shell biochar on the adsorption of Cr(VI) in the wastewater. Fe-modified biochar was obtained from the impregnation with FeNO3 solutions and the surface functional groups of two biochars were examined by infrared spectrometer.The result showed that the Fe-modified biochar had lower abundance of the surface functional groups than that of raw biochar, and had the group of Fe-O.The removal rate of Cr(VI) increased by 94.89% compared with the raw biochar because of existing of the group of Fe-O . The removal rate of Cr(VI) by modified biochar could reach more than 99.0% when the concentration of Cr(VI) was 12μg/ mL, pH 4.0, adsorbent dosage was 0.2g and adsorption time was 2h.
Highlights
Cr(VI) in wastewater mainly comes from leather preparations, chromium plating, industrial pigments, etc
The broad adsorption peak at 3500cm-1-3000cm-1 was formed by stretching vibration of hydroxyl O-H, the adsorption peak around 1700cm-1 was formed by C=O and C=O, and the peaks at 1500cm-11000cm-1 represented the bend vibration peak of C-H.The overall absorption strength of modified biochar was a little lower than that of raw biochar, which indicates that the surface functional groups decreased because of iron materials
The result showed that the raw biochar had only 4.66% removal rate of Cr(VI) in solution and 0.0622mg/g adsorption capacity
Summary
Cr(VI) in wastewater mainly comes from leather preparations, chromium plating , industrial pigments, etc. Cr(VI) has strong toxicity, carcinogenicity and mutagenicity, which can actively migrate and transform among water, soil, atmosphere and biology[1,2].The treatment methods of Cr(VI) in wastewater mainly includes chemical precipitation, electrolysis, reverse osmosis, adsorption, ion exchange and biological methods[3,4]. The adsorption method has good adaptability and effect, which is the main treatment method. Biochar’s adsorption efficiency can be improved by modifying owing to changing its surface properties. Metal ions are adsorbed on the surface of biochar, and the adsorption capacity of biochar to target adsorbents is improved through the mutual adsorption[6]. The influence of biochar modified by iron nitrate on the adsorption removal effect of Cr(VI) by changing concentration of Cr(VI) , adsorption time, pH value and other factors was studied
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