Study On Behavior Of Photocatalysis And Adsorption Of Soil To Pollutants

So many soil forming factors could transform and degrade pollutants and kill nosogenetic microorganisms as well, soil as an environmental control media is of high-efficiency, low-toxicity, in-situ treatment and very cheap to control pollution. Therefore, it has been being paid more and more attention in the field of environmental pollution control. Studies on the absorption of dyes by soil, the processes and mechanism of oxidation degradation catalyzed by soil were conducted in this paper. And the stabilization of phosphorus in waterbody using the soil matrix was discussed, then we compared the flocculation and sedimentation of the blooming algae'with modified soil.1. The behaviors of absorption and photocatalytic degradation of dyes by soil were studied under different temperatures and pHs with soil as the environmental agent. The results indicated that cationic dyes had stronger absorption than anionic dyes on various soils, and they all had activity for degradation of various dyes by photocatalysis. Then we prepared different soil catalyzers by different pretreatments which had different mineral forms and different compositions of organic matter. And the structural factors affecting the photocatalysis degradation were characterized using SEM, XRD and BET.2 Natural soil was used as the catalyst to degrade Sulforhodamine B(SRB) and 2, 4-Dichlorophenol(DCP) under visible irradiation (vis,λ>420nm). The influences of [soil] and [H2O2]0 on the degradation were analysed, the reaction kinetics and mechanism of degradation were studied by UV-Vis, Fluorescence Spectra and IR. The results indicated that SRB could be degraded effectively by chosen Soil/ H2O2/vis agent, complete depigmentation could be achieved in 240min, COD was removed by 90.44% in 10h and DCP was removed by 80.55% in 240min. Fluorescence Spectra results showed that highly active Oxide Species·OH was produced in the reaction. IR results indicated SRB was degraded into small molecular such as amine substances and carbonyl compounds. Catalyst activity did not exhibit any significant loss after 5 recycles. The degradation mechanism was heterogeneous Fenton-like process which was accompanied by·OH production.3. The behavior of the total phosphorus (TP) adsorption by the soil matrix which were sampled from the bank of Xiangxi River was studied in the laboratory under conditions of simulated environment, i.e. different pHs, temperatures and nutrient concentrations, respectively. The experimental results showed that the phosphorous absorptions were fast by the soil matrix of the Xiangxi River, there was a dynamic equilibrium of phosphate concentration between water and the soil(equilibrium concentration is 0.12-0.32 mg/L); under the conditions established in the soil of the former phosphate adsorption, the balance of adsorptions was established after 5 minutes, there are phosphate desorption on partial soil; phosphate concentration was set at six gradients of 0.10, 0.20, 0.40, 0.60, 0.80, 1.60 mg/L, with higher concentrations of the phosphate, soil on the absorption of phosphate increased as well, showing a good linear relationship; acidity (pH 3-10) and temperature(10-30℃) had little effect on the TP adsorption and desorption by the soil matrix. It was concluded that Xiangxi soil matrix could effectively control the phosphorus content of the waterbody to a certain extent.4. The settling characteristics of eutrophication algae settled by soil which was modified with hexadecyl trimethyl ammonium(HDTMA)and chitosan was tested. Four kinds of soil from Xiangxi River were selected as substrate. Changes of turbidity within 250 minutes and chlorophyll a concentration after 8 hours of eutrophication water were tracked. Flocculation algaecide experiment was done using NO.1 soil modified by chitosan to study on the effects of acidity and the removal of nitrogen and phosphorus enriched. The results showed that effect of NO.1 soil modified by chitosan was apparent. The elimination rates of the turbidity and chlorophyll a were 54.36% and 67.87% respectively after 200 minutes. While in the flocculation settling system, the settlement of algae in water body was the best under the condition of pH 6.0. In this condition, the elimination rate of turbidity and chlorophyll a reached 80% and 70.24% respectively after 100 minutes. The selected experimental system had a good mitigation to the enrichment of total nitrogen and phosphorus. The elimination rates of the total nitrogen and phosphorus reached 5.94% and 47.95%, respectively.