At present, the medical and health industry especially veterinary medicine has a lot of, unreasonable application, resulting from varying degrees of pollution to the soil, sediment and groundwater, worrying is that is expanding and spreading. Reasons for the trend spread is mainly manifested in the national support of animal husbandry industry continue to increase, some no breeding technology or breeding technology of low practitioners have an influx of the livestock industry, these newly added practitioners in veterinary drugs is unknown, especially in low price of the beast with the drug tetracycline.

At present, Huazhong Agricultural University is trying to solve this problem by using organic montmorillonite with the characteristics of expansive, large specific surface area and high cation exchange capacity, and has achieved good results. The use of organic montmorillonite in the adsorption of tetracycline in the soil is mainly based on the following characteristics:

1. Organic montmorillonite to tetracycline initial adsorption rate is not very high, but in the two hours after can reach more than 80% of the maximum adsorption capacity, 24 hours basically reached the adsorption equilibrium, achieve adsorption equilibrium time is relatively short, high amount of organic montmorillonite, the quasi second order kinetics equation could better fit the organic montmorillonite to tetracycline adsorption kinetics;

2.The isothermal adsorption curves of 2 Na montmorillonite and organic montmorillonite were all in line with the Langmuir model and the Freundlich model. Organic montmorillonite to tetracycline adsorption capacity 1000-2000mmol/kg were higher than Na montmorillonite (769mmol/kg) and organic montmorillonite to tetracycline performance is mainly affected by the agent and the effect of modification, the maximum adsorption capacity (Qmax) with the length of chain quaternary ammonium salt increased and increased;

3.Freundlich equation fitting results show that organic montmorillonite to tetracycline adsorption parameters (N and KF) were higher than those of sodium montmorillonite, and with the organic modifier amount increases, the parameter n increases, the enhancement of mineral surface heterogeneity, the adsorption of tetracycline enhanced.

4.when pH is low (3 ~ 4), the effect of pH on the organic montmorillonite adsorption of tetracycline most obvious and increased with quaternary ammonium salt added to the amount of increase; organic montmorillonite to tetracycline adsorption partition function gradually decreased as the pH increased from 4 to 5.5); when pH between 5.5 and adsorption distribution coefficient tends to a constant, pH had little effect on organic montmorillonite adsorption of tetracycline (Ref.: Huazhong Agricultural University papers)