Study On Adsorption Dying Wastewater And Regeneration Of Modified Bentonite And Diatomite

Bentonite and diatomite were modified by sodium dodecyl sulfate(SDS) and cetyltrimethylammonium-bromide(CTMAB), and they were characterized by FTIR spectra. The adsorption characteristics and theory, application in printing and dying wastewater and the regeneration methods of SDS-bentonite, CTMAB-bentonite and SDS-diatomite were studied. The main results of this thesis are as follows:(1) Adsorption effect would be influenced by dosing quantity, pH, time and temperature, and the adsorption treatment should be done under the optimal conditions in order to improve adsorption efficiency in practical application. The results showed that the discoloring ratio of methylene blue with SDS-bentonite could reach 99.95% under following conditions: dosage was 0.2g, the adsorption time was 30min, temperature was 45℃and pH value was 7. The discoloring ratio of malachite green with SDS-bentonite could reach on 99.2% under following conditions: dosage was 0.2g, the adsorption time was 45min, temperature was 45℃and pH value was 7. The discoloring ratio of methylene blue with SDS- diatomite could reach on 73.0% under following conditions: pH value was 7, temperature was 25℃and the adsorption time was 20min. The discoloring ratio of malachite green could reach on 85% under following conditions: temperature was 25℃and the adsorption time was 10min.(2) The result showed that SDS-bentonite and CTMAB-bentonite were effective adsorbent to the cationic dye of methylene blue, and the discoloring rate with SDS-bentonite and CTMAB-bentonite was 99.95% and 99.85%, respectively.(3) All of the adsorption data of methylene blue and malachite green with SDS-bentonite could be simulated by the Langmuir equation, while the adsorption data of SDS-diatomite could be simulated by the Langmuir equation and Freundlich isotherm equation well. All adsorption processes of methylene blue and malachite green with SDS-bentonite and SDS-diatomite were accorded with quasi secondary adsorption dynamics. Increasing temperature can improve the adsorption process because it was physical adsorption.(4)The results showed that, compare to the bentonite, the discoloring rate of modified bentonite was improved, among them the CTMAB- bentonite has the best adsorption effect, and the discoloring rate and COD removal rate was 92% and 36%. So, the modification methods of improving discoloring and COD removal rate was the main research.(5) Adsorption ability of bentonite decreased a little after regeneration with hydrogen peroxide, the discolored rate could reach to 90% in the first five times. Therefore, clay regeneration has great use value because it can effectively treat wastewater and reduce cost.