Preparation And Application Of Biomass-based Composite Adsorbent

Biomass,containing a large number of active groups,such as hydroxyl and carboxyl,is a kind of widely available,cheap,renewable and environmental-friendly adsorbent materials.However,biomass has limitations in terms of small adsorption capacity and low adsorption efficiency.It is significant to modify the biomass to prepare cheap and highly efficient biomass-based adsorption materials.Biomass-based adsorbents,by incorporating biomass material with functional material,were prepared in this paper.Also the prepared biomass-based adsorbents were characterized and applied in removing heavy metal ions and dyes from aqueous solution.The main research contents and conclusions of this paper are as follows:CMC/LDHs beads were prepared,which was incorporated with CMC as the matrix and LDHs as functional component.Afterwards,the prepared beads were characterized and applied in removing Cr(?)from aqueous solution.Result showed that CMC/LDHs beads performed good thermal stability,and LDH particles were dispersed uniformly in CMC matrix.CMC/LDHs beads could remove Cr(?)from aqueous solution efficiently.When the initial concentration of Cr(?)solution was 100 mg/g,the adsorption temperature was 30°C and the adsorbent dosage was 12 g/L,the removal efficiency of Cr(?)reached 96.2%.And the adsorption process followed pseudo-second-order kinetic model,Langmuir and Freundlich isotherms models.After CMC/LDHs beads were reused 10 times,the removal effectiveness of Cr(?)remained at around 90%,which suggested that the CMC/LDHs beads have an excellent reusability for the removal of Cr(?).Different types of sawdust/LDHs composite were synthesized with in-situ method,and the surface morphology,crystallization property and thermal stability of the composite were studied respectively.The adsorption behavior of Pb(?)by sawdust/LDHs composite prepared in this study was investigated.The experimental result showed there was a slight difference in the morphology of different types of sawdust/LDHs.Zn-Al-LDHs was spherical while Mg-Al-LDHs and Ni-Al-LDHs were "rosette-like" in shape.Compared with sawdust,the adsorption efficiency of sawdust/LDHs composite was significantly improved.With the initial concentration of Pb(?)of 200 mg/L,the optimum adsorbent dosage of 3 g/L,the optimum initial pH of 6 and the adsorption capacity reached to 32.9 mg/g.In addition,the adsorption process of Pb(?)by sawdust/LDHs composite were modeled by pseudo-second-order kinetic model,also the process followed Langmuir and Freundlich isotherms models.CMC/MOF-199 beads were prepared by using hydrothermal synthesis method and characterized systematically.Then the adsorptive efficiency of N2,CO2,heavy metal ions and dye by CMC/MOF-199 beads were investigated respectively.Result showed that MOF-199 exhibited a well-defined octahedron crystal morphology.Compared with CMC-Cu beads,CMC/MOF-199 beads had much larger specific surface area,better thermal stability and greater adsorption capacity of N2 and CO2.The specific surface area of CMC-Cu beads and CMC/MOF-199 beads were 10.6 m2/g and 380.3 m2/g,the average pore diameter were 36.3 nm and 2.2 nm,the adsorption capacity to N2 were 23.7 cm3/g and 154.1 cm3/g,and the adsorption capacity to CO2 were 16.2 cm3/g and 34.7 cm3/g,respectively.CMC/MOF-199 beads exhibited good efficiency in removing Cr(?),Pb(?),methylene blue,and methyl orange from aqueous solution efficiently,which confirmed that it had a good application potential in the field of adsorption.Pulp fiber/ZIF-8 composite was prepared by in-situ growth method,with pulp fiber as matrix,ZnC12 as mental source and 2-methylimidazole as organic ligand.And the surface morphology,crystallization property and thermal stability as well as its application in adsorption field of the prepared composite were investigated.It was showed that the carboxyl content of pulp fiber had a great influence on ZIF-8 loading in the surface of pulp fiber/ZIF-8 composite.There was more self-assembled ZIF-8 in the surface of composite with the increasing of carboxyl content.Due to high lignin content,unbleached pulp fiber contained more active adsorption sites to react with Zn2+,which was corresponding to more ZIF-8 loading in the surface of unbleached pulp fiber.Compared with pulp fiber,the adsorption capacity of mental ion and dye by pulp fiber/ZIF-8 composite was increased remarkably.For example,the adsorption capacity to Cr(?),Pb(?)by pulp fiber/ZIF-8 was 51.7 mg/g,86.0 mg/g,respectively.And its adsorption capacity to methylene blue and methyl orange was 24.3 mg/g and 18.6 mg/g,respectively.