Effect of Chemical and Thermal Activation on Texture, Morphology, and Composition of Onion Derived Carbon for Arsenic Adsorption
摘要
The huge consumption of onion produces bulk waste (500,000 tons/annum) which leads to environmental issues. This study focuses on the development of biosorbents from the waste onion. The porosity was generated by using HNO3, H3PO4, KOH and NaOH as chemical activators in the 400–800 °C temperature range. Nitrogen adsorption-desorption isotherms were used to explore the effect of activators and temperature on the pore texture and structural parameters of materials which find a way to explore the adsorption study. The carbon samples activated at 600 °C and 800 °C show type IV isotherm with H3 hysteresis. Moreover, the samples activated at 400 °C depict type II isotherm with no hysteresis indicating the absence of porous network at lower temperature. The BET surface area of materials was found in the range of 0.01–635 m2/g. SEM analysis confirmed the porous and rough surface of materials with the development of channels and cavities. The existence of functional groups and their chemical state necessary for the adsorption of contaminants was verified by XPS analysis. A series of samples were then tested for the removal of arsenic. Among all the adsorbent materials onion derived caron activated with HNO3 (ACH6), H3PO4 (ACH3/6), KOH (ACK6) and NaOH (ACNa6) at 600 °C recorded better removal efficiency.