Study On Removal Of P-nitrophenol From Solution By Layer Double Oxide

The removal efficiency of p-nitrophenol (PNP) onto LDO and its regeneration were studied utilizing unique "memory effect" of LDH in this paper. The feasibility of treatment of PNP by synthesizing LDH in-situ was investigated simultaneously. The mechanism of PNP adsorption onto LDO was discussed by adsorption thermodynamics and kinetics. Such analysis instruments as XRD,FT-IR and TEM were adopted. Some main conclusions can be drawn as follows:(1) The removal efficiency of PNP achieved the peak -33% when Mg/Al = 3 : 1, pH=11, p=10mg/L, T = 298K, t=2 h. It showed that the treatment of PNP by synthesizing LDH in-situ was infeasible.(2) The removal efficiency of PNP arrived at 82% when pH = 6,ρ= 100mg/L, T = 303K, t = 2 h, r=150r/min, m/V=0.3g/100mL. The maximal adsorption capacity of PNP onto LDO was 201.83 mg/L, which only accounted for 24.9% of theoretical anion exchange capacity. Most of PNP were adsorpted on the surface of LDO; the arrangement mode of PNP in the interlayer of LDH was slantwise monolayer and the angle tilted was 27°.(3) The adsorption of PNP onto LDO was a spontaneous endothermic and an increasing entropy process. The adsorption occurred because of the static gravitation. Intraparticle diffusion being the rate-controlling step during the adsorption process.(4) The regeneration of the products was carried out by high temperature calcination. The removal efficiency of PNP reached to 89% by calcining 2 h under 450℃. The experiment indicated that regeneration of products was feasible within the four times recycle, and the decreasing of Mg²⁺ ion was one of the important factors resulting in the decline of re-adsorption efficiency.