Study On The Adsorption Characteristics Of Peanut Shells To Dyes Wastewater

The experiment was that agricultural by-product of peanut shells as biosorbent research for adsorption of active dye and methylene blue. In order to inexpensive, highly effective adsorbent provide some theoretical basis.First, the experiment was that the peanut shell were modified by formaldehyde and sulphuric acid as absorbent for adsorption of active yellow (AY) and active blue (AB); Then, we selected supercritical peanut hull(SPH) and heat-decomposed peanut hull (HPH) as biosorbent, and selected menthylene blue (MB) as adsorbate. Bath operation is asopted in experiment. And the characteristics of peanut hull are studied by SEM, FTIR,a specific surface area and pore structure analyzer. The result showed: microscopic structure of treated peanut hulls has become different, and their specific surface area was obvious increased. The treated peanut hulls are beneficial to raising peanut hulls of adsorptive and discolored performance.The effects of pH value, initial concentrations of dyes, biosorbent dosage and size, contact time on adsorption, temperature,and salt concentation of dyes were investigated with the experiment. The optimal adsorption conditions of biosorbent to dyes were determined. The adsorption research of modified peanut shell (MPH) to active dyes is showed:1L of 1 OOmg/L active yellow and active blue solution,10 g biosorbent, pH value 2.0, adsorption time 240min. The adsorption rate of modified peanut shell was above 99%. The adsorption research of Supercritical and heat-decomposed peanut hull to menthylene blue is showed:1L of 100mg/L methylene blue solution,1.6g Supercritical and heat-decomposed peanut shell, pH=7.0, adsorption time 180min, the adsorption quantity of Supercritical and heat-decomposed peanut shells to methylene blue were above 50mg/g.In the optimal adsorption condition, the experimental results for thermodynamics study showed the isothemal data of dyes adsorption all conformed to the Langmuir models, And the adsorption processes of Gibbs functionΔG are also less than 0, The negative value of change in Gibbs free energy (ΔG0) indicates the feasible and the spontaneous nature. The experimental results for kinetic study showed:the absorbing course could be divided into three stages:absorbing faststage, absorbing slowly stage and balanced stage, the adsorption processes coincided with the pseudo-second-order rate kinetics. When the formaldehyde and sulphuric acid modified peanut shells as absorbent to Active Yellow and Active Bule, the activation energy of adsorption (Ea) is 20.60 kJ/mol and 7.79 kJ/mol; When supercritical and heat-decomposed peanut hull absorb menthylene blue, he activation energy of adsorption (Ea) is 7.28kJ/mol and 4.36kJ/mol.