Preparation And Adsorption Properties Of Modified GO/guar Degradable Adsorbents

With the rapid development and progress of global industrialization,a variety of industrial wastewater has posed a serious threat to the water environment and human health.In particular,the problem of large amounts of organic dye wastewater from the textile,paper,pharmaceutical,leather and cosmetics industries is more difficult to solve.At present,adsorption is recognized as the most effective and economical treatment method.Graphene oxide(GO)is an ideal adsorbent material,but it is easy to agglomerate due to its large specific surface area,high surface energy.Thus,grafting modification on GO is required to improve its dispersibility and adsorption performance.The emerging gel adsorption technology has become a research hotspot because of its advantages of quick recovery,no secondary pollution and low operating cost.Natural polymer as guar gum(GG),possess low cost,biodegradable,environmentally friendly and so on,has attracted much attention.Therefore,we prepare a novel degradable composite gel by cross-linking GO with GG,which has high adsorption properties and can effectively remove organic dye form wastewater.In this study,a novel p(AA)-g-GO material was prepared by grafting polymerization of acrylic acid(AA)onto grapheme oxide(GO)skeleton.The adsorption capacity of methylene blue(MB)by p(AA)-g-GO increased with the p H,temperature,contact time and initial dye concentration.Langmuir model showed that the maximum adsorption capacity was about 1448.2 mg/g at 25 ?.More importantly,the material maintained excellent adsorption capacity after 5 adsorption-desorption cycles and showed significant selective adsorption for methylene blue/methyl orange mixed solution at p H=10.The equilibrium adsorption capacity of cationic dyes such as malachite green(MG),basic magenta(BF)and rhodamine B(Rh B)reached 582.1,571.7 and 437.1 mg/g,respectively.The mechanism analysis indicated that electrostatic interaction,?-? conjugation and hydrogen bonding are the main forces for cationic dyes adsorption.In this study,acrylic acid homopolymer crosslinked guar gum/graphene oxide(AA-co/cl-GG/GO)composite gel was prepared by thermal crosslinking method.Characterization results on the surface morphology,chemical composition,thermal degradation behavior and swelling property showed that the GG6(6 m L AA dose)had better gel characteristics.The influences p H,temperature,initial dye concentration,contact time,the optimal adsorption conditions on adsorption capacity for MB were explored.Moreover,the removal of MB from wastewater indicated rapid kinetic behavior and the maximum adsorption capacity was up to 572.1 mg/g according to Langmuir model.Due to its advantages of convenient recycling and easy regeneration,the relative adsorption percentage was still exceeds 85% after 6 cycles and maintained good stability.Specially,FTIR analysis showed that the natural properties of GG endowed the gel biodegradation performance.