Studies On The Transport Of Phenol And Cd²⁺ Complex Pollutants In Soil Modified With Amphoteric Modifier

This paper is the saturated soil transport experiment, compared with the nonreactive solute Cl-, the transport and elution characteristics of reactive cadmium ion (Cd²⁺) and phenol in water saturated Lou soil & red-earth-derived-paddy-soil (Full text referred to as the "Red Soil") column modified with four amphoteric modifiers: N-dodecyl-β-amino-propylacid (AR₁₂), dodecyl-dimethyl-betaine (BS₁₂), dodecane glycine imidazoline (AS₁₂) and alkyl-dimethyl-betaine (BS8). The results are as follows:1.CDE equilibrium transport model can be used to simulate Cl- transport breakthrough curve (BTC) in amphoteric modified soils, the retardation factors R of Cl- are smaller than 1 and are in order of CK (Lou soil)>AS-12 (100% AS₁₂ modified Lou soil)>BS-8 (100% BS8 modified Lou soil)>AR-12 (100% AR₁₂ modified Lou soil)≈BS-12(100% BS₁₂ modified Lou soil)≈50% BS-12 (50% BS₁₂ modified Lou soil), CK (Red soil)>AS-12 (100% AS₁₂ modified Red soil)>AR-12 (100% AR₁₂ modified Red soil)≈BS-8 (100% BS8 modified Red soil)≈50% BS-12 (50% BS₁₂ modified Red soil)>BS-12 (100% BS₁₂ modified Red soil). These due to the changes of physical structure, surface charges and hydrophilicity-hydrophobicity of modified soils with different amphoteric modifiers.2.The reactive solute Cd²⁺'s BTC is simulated better by CDE nonequilibrium transport model in amphoteric modified soils. R of both Cd²⁺ and phenol+Cd²⁺ treatments in modified Lou soils follow the order of BS-12>50% BS-12>AR-12>CK>BS-8>AS-12>1; the order of R in modified Red soils with Cd²⁺ and phenol+Cd²⁺ treatments always is AR-12>BS-12>50% BS-12≈CK>BS-8>1. The retardation effect of Cd²⁺ is confirmed in the BS-12, AR-12 modified soils but weakened in the AS-12, BS-8 modified soils. These results are mainly affected by the changes of surface charges.The final residual retentions of Cd²⁺ in soils are used to assess the Cd²⁺ retention capacity of soils. The order is BS-12>50% BS-12>AR-12>BS-8>AS-12>CK in Lou soils and BS-12>50% BS-12>AR-12>CK>BS-8 (Cd²⁺ single) & AR-12>BS-12>50% BS-12>CK>BS-8 (Cd²⁺+phenol) in Red soils. The AR₁₂, BS₁₂ amphoteric modification can enhance the retention ability and adsorption stability of Cd²⁺. The Cd²⁺'s retention in the BS-8, AS-12 modified Lou soils are greater than the original soil because of eluted Cd²⁺ very few.3.CDE nonequilibrium transport model can be a very good simulation of phenol in the amphoteric modified soils, R of phenol in modified Lou soils follow BS-12>AR-12>AS-12>50% BS-12>CK≈BS-8 and AR-12>BS-12>AS-12>50% BS-12 >CK≈BS-8 in modified Red soils. In addition to BS-8 modified soil, the other modified soils can increase the retardation effect on phenol. The main reason due to modification of modified increasing soil surface hydrophobic, and the longer carbon-chain, the more hydrophobic.The order of residual retention of phenol is AR-12>BS-12>50% BS-12>AS-12 >CK≈BS-8 in modified Lou soils and BS-12>AR-12>50% BS-12>AS-12≈CK≈BS-8 (single phenol), AR-12>BS-12≈50% BS-12>AS-12>CK≈BS-8 (Cd²⁺+phenol)in modified Red soils. AR-12, BS-12, AS-12 soils on the retention capacity of phenol are increased significantly, but BS-8 do not change significantly.4.By the mixture of phenol and Cd²⁺ transport studies, there is the obvious antagonistic effect between Cd²⁺ and phenol in BS-12, BS-8 soils, but the synergistic effect in AR-12 modified soils.