Preparation Of Clay/Jute Composites And Their Adsorption Properties Of Cu(?),Cr(?) And Methylene Blue

In recent years,the rapid development of urbanization and industrialization brings seriously environmental pollution problems,especially for the water pollution,which becomes more and more urgent.The adsorption strategy is one of the most cost-effective purification processes for sewage,and the adsorbents are the key factor.The widely used adsorbents are activated carbon and polymer-based composites.However,in the preparation of activated carbon adsorbent,it is highly energy-consuming and can produce greenhouse gases.The polymer-based adsorbents are complicated in production process and cause possible secondary pollution due to their degradation-resistant nature.Therefore,the preparation of ecologically efficient,inexpensive and abundant adsorbents is the key point in the adsorption purification of wastewater.Clays are rich in reserves,and of unique layered structure and ion exchange capacity,being ideal raw materials for adsorbents.The biomasses of agriculture and forestry have a large number of active functional groups that can be used as the adsorption sites.The adsorption materials prepared from clays and biomasses are ecological,low-price and abundant.Based on this idea,this work investigates the synthesis and adsorption properties of the composite adsorbents using clays and jute as the major raw materials via two-roll mill method and wet-ball grinding method.Their adsorption behaviors totards Cu???,Cr???and methylene blue?MB?have been systematically investigated.The main research contents and results of this paper are as follows:?1?Orthogonal experimental study on the preparation of clay/jute composite by two-roll mill method.The orthogonal test was designed with jute powder type,clay type and mass,water?50^oC?mass and polyacrylamide?APAM?mass as the factors,and the adsorption capacity to Cu???was taken as the influence result to obtain the optimal processing parameters.When the mass ratio of the bentonite/jute leaf powder/APAM is 3:10:6,the as-obtained jute/bentonite adsorbent?B-opt?exhibits the highest adsorption performance to Cu???.The optimal adsorption conditions for Cu???were determined by the single-factor experiments by changing p H,dosage?d?,initial solution concentration?C₀?,adsorption time?t?and adsorption temperature?T?.When d=3 g/L,C₀=1000 mg/L,p H=5,T=50^oC,and t=60 min,the adsorption capacity of Cu???reaches 327.9 mg/g.The results of phase and morphology characterization indicated that the clay/jute composite adsorbents hav a multistage porous structure.?2?The adsorption behavior of clay/jute composite adsorbent.The effects of p H,dosage,initial concentration,adsorption time and adsorption temperature on the adsorption properties of Cu???,Cr???and MB by B-opt were studied by single-factor experiments,and the optimal conditions to adsorb Cu???,Cr???and MB were obtained by using the B-opt sample as the model system.The B-opt sample exhibits an adsorption capacity of 327.9 mg/g to Cu????d=3 g/L,C₀=1000 mg/L,p H=5,T=50^oC,and t=60 min?,an adsorption capacity of 30.81 mg/g to Cr???.?d=1.5g/L,C₀=50 mg/L,p H=2,T=45^oC,and t=100 min?,and an adsorption capacity of 165.9mg/g to MB?d=2.3 g/L,C₀=400 mg/L,p H=10,T=60^oC,and t=150 min?.The results of EDS spectra and elemental mapping show that Cu???and Cr???are uniformly adsorbed on the adsorbent surface.The experimental data were fitted according to various adsorption kinetics,isothermal adsorption and thermodynamic models.The fitting results suggest that the adsorption processes of Cu???,Cr???and MB on the B-opt sample accord with the pseudo-first-order kinetic model and the Langmuir model,indicating that these adsorption is homogeneous monolayer and spontaneous endothermic reaction.?3?Preparation of bentonite/kaolin/jute composite adsorbent by the wet ball milling method.Using the wet ball milling process,the mixed clays?bentonite/kaolin with mass ratio 1:1?and jute leaf powder were used as raw materials,and the orthogonal experiment was carried out using the masses of jute powder,mixed clay and APAM as the factors.The adsorption capacity of Cu???was used as the target property for the orthogonal analysis.The results showed that when the mass ratio of clay,jute leaf powder and APAM was 3:10:6,the adsorption capacity of Cu???on the bentonite/kaolin/jute composite adsorbent?JBK-F?was the highest value of 359.8mg/g characterizations of phase and microstructure show that the as-obtained composite adsorbent is of a multistage porous structure,which is beneficial to the adsorption of heavy metal ions and dyes.?4?Adsorption behavior of the bentonite/kaolin/jute composite adsorbent.Using the JBK-F sample as a model adsorbent,the effects of p H,dosage,initial concentration,adsorption time and adsorption temperature on their adsorption performance were systematically investigated.When d=2.5g/L,C₀=1000 mg/L,p H=5,T=40^oC,and t=70 min,the adsorption capacity of Cu???on JBK-F composites was as high as382.8mg/g.When d=1.1 g/L,C₀=100 mg/L,p H=2,T=40^oC,and t=80 min,the adsorption capacity of Cr???on the JBK-F composite was 88.13 mg/g.When d=2.7g/L,C₀=600 mg/L,p H=9,T=55^oC,and t=140 min,the adsorption capacity of MB on the JBK-F composite was 220.9 mg/g.The fitting results of kinetic and thermodynamic models show that the adsorption processes of Cu???,Cr???and MB on the JBK-F sample conform to the pseudo-first-order kinetics and Langmuir models,belonging to a homogeneous monolayer adsorption process.The adsorption reactions of Cu???,Cr???and MB on the JBK-F sample are endothermic and spontaneous.