Exploitation and study on the adsorbents in treatment of dye effluent

摘要

The characteristics, affecting factors and mechanisms of adsorptive removal of different dyes by different waste materials, such as wood chips, rice straw,corn straw, peanut shells, wheat bran and so on, with low cost were investigated.Additionally, the characteristics of dyes adsorption by modified waste materials with biological pretreatment and chemical treatment were also studied. The Fourier Transform Infrared Spectroscopy (FTIR), UV scanning and the characteristics of adsorption heat were used to analyze systematically the mechanisms of dye adsorption by original and modified waste materials. The results showed that heterocyclic dyes and some triphenylmethane dyes could be adsorbed easily by waste materials, for instance, the adsorption capacity of Azure B, methylene blue and malachite green could reach 22.3mg/g , 22.2mg/g and 15.5mg/g respectively. However, the azo and anthraquinone dyes were less effective. Different adsorption conditions, such as temperature, grain diameter and so on would affect the adsorptive effects. In addition,after pretreatment with these waste materials by biological modification using white rot fungus to degrade these materials for an appropriate time, these pretreated materials were further modified with chemical method. The adsorptive effects of these combined modified waste materials could be enhanced remarkably, the adsorption rate (malachite green) was 6.5 folds than that of original materials, and the value could be up to 100.75mg/g. Furthermore, the FTIR and UV scanning showed that the mechanisms of adsorption by these materials might attribute to the strong interaction force, such as covalent bond or ion-exchange, and the interaction force was formed by interaction between the carboxylic, hydroxyl, amidocyanogen and phosphoric group on the surface of waste materials and dyes. Meanwhile, the CH2- group on the surface of some waste materials was packed by some dyes. Equilibrium isotherm data could be well described by Frenundlich model and adsorption of some dyes could be carried on easily by the mode of polymolecular layers.