Bisphenol A adsorption using hydrothermal carbonization derived biochar resulting from Casuarina equisetifolia L. and Wrightia tinctoria.

The removal of bisphenol A (BPA) from aqueous solutions using hydrothermal carbonization (HTC) derived biochar was used as adsorbent. In this study, biochars of Casuarina equisetifolia L. (CE) and Wrightia tinctoria (WT) were prepared using Hydrothermal carbonization method at three temperatures (180°C, 215°C and 250°C) with autogenous pressures and constant reaction time of 10 min after reaching desired temperature. The produced char is then extracted with acetone to remove most of the oils and volatiles present; the char is then dried in oven to remove remaining solvent and volatiles. SEM analysis was performed on the biochars to learn how the topography has changed due to the temperature change. BPA solution was prepared in house by dissolving 0.02g of BPA in 500mL of distilled water to make 40ppm of solution, then 0.05gm of adsorbent (biochar and activated carbon) was added to the solution and kept in a shaker, the solution was periodically pipetted (5mL) from the 500mL solution for about 160 min (equilibrium condition). The collected solution was then analyzed using double beam UV/Visible spectrometer with 277.5nm wavelength, Concentration vs Time was calculated using this analysis, adsorption percentage, adsorption capacity and experimental qe was calculated using the data collected by UV/Visible spectrometry. Two kinetic models based on Freundlich and Langmuir adsorption isotherms were used to analyze the adsorption capacity of the adsorbent (activated carbon and biochar) mathematically and plot the required graph for linear regression. The results obtained via linear regression showed that biochars produced via hydrothermal carbonization (CE215, CE250 and WT250) showed higher possibility of using them as adsorbents, which could well perform better than any other alternative carbon adsorbent. [ABSTRACT FROM AUTHOR]