Study On Extraction Of Peanut Hull Flavones And Its Residue Adsorption Performance Of Heavy Metal Ion

With peanut shells as raw material, through the single factor and orthogonal we found the optimal extraction conditions of flavone were: 5.0 g peanut shells, 100 mL pH 2.0, 60% ethanol solution, 70℃extraction 24 h, the extraction rate may up to 2.59%, and it was indicated that it has some antioxidant activity. Moreover, nitric acid and epichlorohydrin(ECH) were used to modify peanut hull respectively. Single factor and orthogonal experiments were used to find the best modification conditions, and its optimal static adsorption conditions of Cu²⁺ and Ni²⁺ in aqueous solution.The optimum preparation conditions of peanut hull sorbent with nitric acid were as follows: 8.0 g peanut hulls respond 3 h with 100 mL 10% nitric acid solution in 80℃. Its optimum adsorption conditions to Cu²⁺ were: 0.5 g modified peanut hulls, 100 mg/L pH5.0 Cu²⁺ solution 50 mL, under 30℃shakes 4 h; The optimum adsorption conditions to Ni²⁺ were: 1.0 g adsorbent, 50 mg/L pH 8.0 Ni²⁺ solution 50 mL, under 25℃shakes 6 h. The optimum preparation conditions of ECH modified peanut hull were: 5.0 g peanut hulls respond 40 min with 100 mL 1.5 mol/L sodium hydroxide in 30℃. Its optimum adsorption conditions to Cu²⁺ were: 0.3 g adsorbent, 50 mg/L pH5.0 Cu²⁺ solution 50 mL, under 30℃shakes 3 h; The optimum adsorption conditions to Ni²⁺ were: 0.6 g adsorbent, 50 mg/L pH 8.0 Ni²⁺ solution 50 mL, under 30℃shakes 3 h. By comparison, the adsorption capacity of two adsorbents to Cu²⁺ all surpassed Ni²⁺, and the adsorption performanc of ECH modified peanut hulls was better than nitric acid modified peanut hulls.Studies on the adsorption kinetics and thermodynamics laws of modified absorbent to Cu²⁺was taken, which discovered that adsorption dynamics was more in line with Lagergren pseudo-first dynamic model. The isothermal adsorption thermodynamics equation may be represented as Ce Qe= ?1. 7806+8.0470Ceor Q e = 0 .1523C_e^1.9137, which proved that the Langmuir and Freundlich isothermal adsorption thermodynamics model all can good fit to the thermodynamics adsorption process. Compared with the absorption in batches, Column bed dynamic adsorption capacity was much higher. The better adsorption effect will be achieved with the less velocity, the lower imported ion concentration, and the higher bed layer, but the adsorption rate is relatively lower. The used absorbent can be regenerated by elution with 1% HCl. Certainly, the problem of how to match the economy does exist in reality.According to fixed bed absorbing-breakthrough curve theory, the standard breakthrough equation has an"S"sharp. The curve of concentration and influent fixed bed volume can be fitted to the equationy = Ae^R₀x. Under the room temperature, the fix-bed kinetics equation can be written as 2 (2.38821.63802)q = ( 20.4919C?15.9271C)Ï„^{2.3882c-1.6380c2}.A preliminary study of competitive adsorption on Cu²⁺ and Ni²⁺ coexistence system was carried. Results indicated that, under the non-competition condition the Ni²⁺ loading capacity and adsorption rate was all smaller than Cu²⁺. But in the dual competition system, Cu²⁺ and the Ni²⁺ adsorption capacity had an obvious drop, and the Ni²⁺ adsorption capacity is bigger than Cu²⁺ significantly, which indicated that the adsorption stability of Ni²⁺ is higher than Cu²⁺, during the adsorption process an adsorption sites exchange was existed in competitive absorption system.Experiments showed that the peanut hulls can be used to extract natural antioxidants, and its residue with chemical reagents preliminary treatment can be used as heavy metal sewage disposal agent.