| Abstract | Sulfhydryl material is a kind of favorable solid absorbent. It can steadily absorb cadmium ion in solution. Generally, it’s specialties include strong selectivity, high efficiency and velocity of absorption, convenient for operation, etc. sulfhydryl cotton fiber is a kind of representative sulfhydryl material. This thesis systemically expound the preparation, mechanism and speciality of sulfhydryl cotton, as well as its application in the treatment of waste water containing cadmium.
The content and mechanism intensity of sulfhydryl is the main guidelines of scaling the quality of sulfhydryl cotton preparation. High quality sulfhydryl cotton fiber should be moderate sulfhydryl content, whiteness color and luster, and the length and intensity no lower than original absorbent cotton. The intensity of sulfhydryl cotton itself and the content of sulfhydryl are effected by several factors including the proportion of ingredients, temperature and time of preparation, and quality of sulfhydryl acetic acid, etc. The factors restrict one another.
The absorption of cadmium by sulfhydryl cotton is the co-functionary result of physical and chemical absorption. Thereinto, chemical absorption gives priority to the result. The reaction formula is: 2RSH+Cd2+=[RS-]2Cd+2H+。
The sulfhydryl cotton research of factors in the treatment of waste water containing cadmium: If PH = 4.5~10, sulfhydryl cotton can well absorb cadmium ion in solution. If sulfhydryl material is sufficient, absorptivity is scarcely influenced by velocity of flow. Compared with common absorbents, sulfhydryl cotton gets a faster absorption velocity. Absorptivity is scarcely influenced by concentration. Under a certain velocity of flow, improving the concentration of solution may even trend a higher absorptivity. Under a certain cadmium concentration, absorptivity improves along with the quantity of sulfhydryl material. When the usage of sulfhydryl material is over 0.2g, the absorptivity could reach 100%. Sulfhydryl cotton has strong selectivity - the ions of alkali metals and/or alkaline-earth metals (Na+, K+, Ca2+, Mg2+, Fe3+, Al3+, etc.) can hardly be absorbed by sulfhydryl cotton. Under certain concentration, along with the volume improvement of solution containing cadmium, remainder concentration of leaking liquor improves until C=C0. Absorptivity is hardly influenced by temperature (0~40). Sulfhydryl cotton can reuse several times after washing and desorbing by diluted hydrochloric acid. Absorptivity and saturation quantum do not reduce. Times of reuse, as well as saturation quantum, decrease along with the improvement of acidity of regeneration liquor.
This thesis probes into the technics flow and factor of waste water treatment. The technics of the combinative method of chemical deposition and sulfhydryl material absorption is provided with following excellence: The usage of chemical deposition in prophase makes sediment low water containing. The consequent filtration makes fast and effective separation of liquid and solid. Grain content in filtrate is low enough. In anaphase, the usage of sulfhydryl material won’t lead the toxic incidence caused by multivalence metals, Fe3+, Al3+ for instance. The selectivity of sulfhydryl cotton results in almost no absorption to innocuity ions in water, Na+, Ca2+, Mg2+ for instance. So, the times of regeneration treatment reduce. When touches the cadmium waste water, sulfhydryl material can eliminate cadmium ions immediately, needed a fat lot settle time. Limited diluted hydrochloric acid uses in regeneration of sulfhydryl cotton. So the concentration of cadmium is high, which is propitious to reuse. The regeneration of sulfhydryl material do not reduce saturation absorption capability. |
