Study On The Treatment Of Electroplating Wastewater By Bentonite And PAM

In order to improve the utilization of water resources, reduce electroplating wastewater pollution to the environment and cut down cost of water, electroplating wastewater was treated and recycled by bentonite/PAM-RO integration technology in this paper. First, betonies were modified by hot activation, loading chitosan, PAM, surfactant and magnetic Fe3O4. In static condition, this paper studied on the effect of bentonite and modified bentonite to the heavy metal Cu2+ and Ni2+ adsorption, and then studied on the treatment of electroplating wastewater by bentonite and PAM, researching the effect of dosage, contact time, initial concentration, dosing sequence and pH on the adsorption. Bentonite/PAM-RO process and NaOH-PAM-RO process was comparatively studied on the treatment of mixed wastewater from an electroplating wastewater plant in zhongshan city. Finally, bentonite adsorption properties and adsorption mechanism were discussed, and the main conclusions obtained as follows:(1) Bentonite was a good adsorbent, comparing to other kinds of modified bentonite, the adsorption rates were more than 99% when shaking time was 15min, the dosing of adsorbents was 40g/L, the constant speed was 150 rpm, the reaction temperature was 30℃for the electroplating wastewater with 51.25 mg/L Cu2+,47.10 mg/L Ni2+ 35.08 mg/L Zn2+.(2) The dynamical data for the adsorption of Cu2+ and Ni2+ fitted well with the pseudo-second-order kinetic model. It can be seen that adsorption isotherms of Langmuir model was much better than other models. The adsorption process was spontaneous and endothermic.(3) The electroplating wastewater was first treated by bentonite, and then treated by PAM. The synergistic effect was found in the process of the treatment of electroplating wastewater by bentonite and PAM. The neutralize precipitation/PAM-RO method and bentonite/PAM-RO were apllied separately in treating electroplating wastewater, it was showed that bentonite method was better than neutralize precipitation method for water flux, membrane water quality and water conductivity of effluent. (4) The X ray diffraction, IR Spectrum and SEM micrographs of bentonite and the bentonite which adsorped Cu2+,Ni2+ showed that the adsorption mechanism of bentonite was mainly the ion exchange adsorption and surface linking.