Preparation Of Magnetic-CNC/Diatomite Composite And Study Of Its Adsorption Properties

With the problem of water pollution increasing,adsorption treatment of wastewater is becoming a research hotpot due to its low cost,eco-friendly,efficiency and stable properties.Cellulose nanocrystal（CNC）and diatomite were used as row materials to synthesize magnetic cellulose nanocrystal diatomite（CNCD）composite and the optimal conditions of preparation were discussed in this paper.CNCD was modified by Fe3O4 through in-situ to prepare magnetic-cellulose nanocrystal diatomite（MCNCD）adsorbent.Then,MCNCD was used as adsorbent for treatment of wastewater containing methylene blue（MB）,Pb²⁺,Cu²⁺,respectively.The influences of primary concentration of wastewater,adsorption time,pH and temperature were studied.The main results are as follows:（1）The results of CNCD preparation showed that the optimal condition preparing CNCD is the ratio of CNC to diatomite 1:1,pH 7,temperature 60℃and stirring 3 h.MCNCD with superparamagnetism was prepared through in-situ with Fe3O4.SEM,IR,XRD,BET,TGA and VSM were used to characterize MCNCD.（2）MCNCD adsorbent was used to treat wastewater containing MB.The results showed that,under the primary concentration of wastewater 20 mg/L,the optimal performance of MCNCD adsorbent were temperature 30℃,pH 9 and adsorbing time 300 min.Under this condition,the adsorption capacity was 56.72 mg/g.（3）MCNCD adsorbent was used to treat wastewater containing Pb²⁺.The experiment results showed that MCNCD had the highest adsorption capacity for Pb²⁺（primary concentration is 10 mg/L）under the conditions of temperature 30℃,pH 5,adsorbing time 120min,which was 40 mg/g.（4）The experiment of MCNCD treating Cu²⁺wastewater showed that the suitable condition treating Cu²⁺wastewater（primary concentration is 10 mg/L）were at temperature30℃,pH 6,adsorbing time 120 min.Under this condition,the adsorption capacity was 19.3mg/g.（5）Kinetics and isotherm model were used to fit the curves of MCNCD adsorbing MB,Pb²⁺,Cu²⁺.The results stated that the experimental kinetic data fit the pseudo-second order model very well.Moreover,the adsorption process for MB,Pb²⁺,Cu²⁺were better described by the Langmuir,Freundlich and Langmuir isotherm model,respectively.（6）The regenerative experiment indicated that MCNCD has better renewability,the adsorption of MB,Pb²⁺,Cu²⁺were 52.1 mg/g,23.45 mg/g and 5.04 mg/g after three times adsorb-desorb recycle,respectively.The above conclusion indicated that MCNCD has excellent properties of adsorption and regeneration.The study of the MCNCD as adsorbent,a kind of novel composite material,will provide theoretical direction for the extending application of CNC-based materials.