Removal of Methylene Blue from Aqueous Solution using Porous Biochar Obtained by KOH Activation of Peanut Shell Biochar

Abstract

aBiochar from peanut shell was used as the precursor for the preparation of porous biochar by KOH activation. The pore structures of porous biochar also were characterized by scanning electron microscopy (SEM) and N2 adsorption/desorption. The adsorption performance for the removal of methylene blue (MB) was deeply investigated. The effects of impregnation ratio (KOH/biochar: w/w), activation temperature, and activation time on the removal of methylene blue by porous biochar were evaluated. In addition, the effects of initial MB concentration and pH value on the adsorption process were also studied. The optimum conditions for preparing porous biochar were obtained with 1.5:1 of impregnation ratio, 800 °C of activation temperature, and 90 min of the holding time in activation. Results indicated that the adsorption capacity was high even at higher initial MB concentrations. The adsorption process followed pseudosecond-order kinetics. The experimental adsorption isotherm was found to be best fitted with the Langmuir model, which implying that the adsorption of MB by porous biochar proceeded as a monolayer adsorption, and the maximum monolayer adsorption capacity of MB was 208 mg•g -1 .

Removal of methylene blue from aqueous solutions using biochar prepared from Eichhorrnia crassipes (Water Hyacinth)-molasses composite: Kinetic and equilibrium studies

“…A comparison of the R 2 values suggests in table 4 that experimental data fitted well into pseudo-second order adsorption process. This trend has been reported by other researchers who have worked with similar bio-based adsorbents (Han et al, 2015;Tan et al, 2016).…”

Simultaneous capture removal of phosphate, ammonium and organic substances by MgO impregnated biochar and its potential use in swine wastewater treatment

“…Thus, the Mg-biochar can be used as an efficient adsorbent for humate removal at relatively higher pH values. Han et al (2015) also found KOH activated peanut shell biochar could effectively remove organic pollutants from aqueous solutions. Obviously, the ammonium adsorption capacity was increased when the pH rose to 7.0 and remained more or less constant (~21 mg/g) at pH 7.0 -8.5, suggesting that ammonium was responding to the diminishing positively charged Mg-biochar surface.…”

On the comparison of pseudo-first order and pseudo-second order rate laws in the modeling of adsorption kinetics

“…All of these works [41,42,43,44,45,46,47,48,49,50] concluded that K2 better described the experimental kinetic data, except in ref. [49] in which K1 gave a better fit in the case of As(V) adsorption (while K2 was more satisfactory in the case of Cr(III) and Cr(VI)).…”

“…Among these publications 4 could not be used because all of the data were at equilibrium [41,42,43,44]. As a consequence, these studies unsurprisingly reported better performance of K2 over K1 as noted in section 3.1.…”