The Adsorption Mechanism Of Zinc Oxide On Typical Pollutants:Effect Of Dissolved Organic Matter

Typical pollutants that migrate and transform in the water environment have always been the focus of attention.For example,heavy metal ion copper is toxic to the growth and development of plants and animals,and phosphorus makes the lake eutrophic.The adsorption method is widely used in the current method of treating water pollution.Therefore,various kinds of adsorption materials have been developed and applied in recent years.However,there are few studies on the effects of extensive humus in nature.To study the effect of humic substances(humic acid and fulvic acid)on the adsorption of typical pollutants(selecting copper ions and phosphorus)by zinc oxide(nano-zinc oxide)in complex ternary systems.This experiment studied the mechanism of humus's migration and transformation of copper and phosphorus in the environment by controlling the amount of humus added and the order of addition,and systematically explored the effects of natural organic matter(HA/FA)on the adsorption of typical pollutants by zinc oxide under different conditions.(1)The effect of HA on the copper adsorption on zinc oxide experimentally shows that the presence of HA significantly inhibits the adsorption of Cu(?)by zinc oxide;the effect of zinc oxide on the adsorption of Cu(?)ions is optimal when the pH is 5.05,and the NaNO3 concentration the maximum adsorption amount was 21.79 mg/g at 1.0 mol/L,and the maximum adsorption amount is achieved in the experimental group with HA added at pH 5.05 and the control group without HA.With the increase of temperature,the adsorption of copper ions by zinc oxide increases.The adsorption model conforms to Freundlich's formula.The effects of HA addition sequence and its adsorption capacity are as follows:control group(without HA addition)>post-addition>simultaneous addition>first addition.From the FTIR spectra and SEM images,HA and Cu(?)have competitive adsorption effect on the adsorption sites on the surface of zinc oxide particles,and the hydroxyl groups on the surface of zinc oxide plays an important role in the adsorption of HA and Cu(?).(2)The effect of HA on the adsorption of phosphorus on zinc oxide The experimental results show that:HA has obvious inhibitory effect on the adsorption of phosphorus by zinc oxide.Under the optimal pH conditions,the amount of adsorption in the control without HA was 30%higher than the group with HA,and the phosphorus adsorption decreased with increasing HA concentration.The effect of HA addition sequence on phosphorus uptake by zinc oxide was as follows:control group(without HA addition)>post-addition of HA>simultaneous addition of HA>post-addition of zinc oxide>post-addition of phosphorus.The characteristics of FTIR spectra showed that there are competive adsorption of humic acid and phosphorus were Adsorption sites of zinc oxide surface.(3)The experimental results of phosphorus adsorbed on nano-ZnO by FA showed that tthe amount of phosphorus adsorbed by zinc oxide decreases with the increase of FA concentration,when the concentration of FA is in the range of 5 to 70 mg/L.And the experimental group did not add FA that had an equilibrium adsorption capacity of 23.53 mg/g.and the addition of FA significantly inhibited the adsorption of phosphorus by nano-ZnO.In the different addition order and the control group,the ionic strength of the solution also inhibited the adsorption of phosphorus by the nano-ZnO.When the concentration was 0.1 mol/L,both the control group and the experimental group reached the same adsorption capacity.The change of pH value has a great influence on the adsorption of phosphorus by nano-ZnO,and the change trend of the adsorption capacity of the control group and the experimental group is basically the same.The maximum adsorption capacity are reached at a pH value of about 5.10.It showed that it is not conducive for absorption of phosphorus by nano-zinc oxide in both acidic and alkaline conditions.Increasing the temperature favors the adsorption of phosphorus by nano-zinc oxide,but the high temperature(at 35 ?)is not conducive to adsorption.The effect of FA addition sequence on the adsorption of phosphorus by nano-ZnO was:control group(without FA)>post-FA addition>simultaneous addition>after addition of P>nano-ZnO.