Preparation Of Bagasse Derivatives And Their Adsorption Performance On Contaminants

Because of their extreme toxicity and non-biodegradability,heavy metal ions and dyes do considerable harm to human health and the natural environment.The use of an adsorption approach to treat such contaminants has the advantages of being easy,cost-effective,and environmentally acceptable,especially with the development of renewable bagasse（BG）,a form of biomass adsorbent that is critical to resource recycling and sustainable development.BG has a large specific surface area and readily graftable functional groups,but its adsorption capacity is limited,necessitating chemical modification to achieve efficient adsorption.Since carboxyl functional groups influence the efficacy of adsorbents significantly.In this dissertation,cellulose-sodium polyacrylate and carboxymethylcellulose aerogels were produced by grafting acrylic acid（AA）and chloroacetic acid（MCA）onto BG cellulose,and the adsorption of heavy metal ions and dyes was investigated.The primary research included the following:（1）Cellulose（CE）fibers were obtained after sugarcane bagasse（BG）was treated with sodium hydroxide（Na OH）and bleached to separate the non-cellulose composition.A cellulose-sodium polyacrylate（CE-PAANa）was effectively synthesized through the simple free radical graft polymerization of cellulose ester（CE）with acrylic acid（AA）using potassium persulfate（KPS）as the initiator.The effect of p H,contact time,and solution concentration on bulk adsorption capacity was studied.The adsorption kinetics were in reasonable agreement with the pseudo-second-order kinetic model,and the adsorption isotherms were consistent with the Langmuir model,indicating that the adsorption was a chemical force-dominated single-molecule layer adsorption.The Langmuir model calculated maximal adsorption capacities of106,3,333,3,and 163,9 mg/g for Cu（II）,Pb（Ⅱ）,and Cd（II）,respectively.In addition,X-ray photoelectron spectroscopy（XPS）and energy-dispersive X-ray spectroscopy（EDS）results revealed that cationic exchange and electrostatic interaction were the primary heavy metal ions adsorption mechanisms.In addition,CE-PAANa has a high adsorption capacity for only cationic dyes,proving that electrostatic effect plays a significant role in adsorption.（2）BG carboxymethyl cellulose（BGCMC）with a high degree of substitution（DS）was produced by adjusting the proportions of monochloroacetic acid（MCA）and sodium hydroxide to BG cellulose.BGCMC aerogels（BCGel）were produced by crosslinking citric acid（CA）with sodium hypophosphite（HPS）as a catalyst.The adsorption results were better described by the Langmuir isotherm（R²>0.99）,with the maximal adsorption capacities of BC₃Gel for Pb（Ⅱ）and MB being 353.36 and 1260.10 mg/g,respectively.In addition,after treatment with50%alcohol or 0.05 M EDTA solution,BCGel demonstrated satisfactory removal performance after five regeneration cycles.Results from X-ray photoelectron spectroscopy（XPS）and energy-dispersive X-ray spectroscopy（EDS）indicated that cationic exchange and electrostatic interaction were the primary adsorption mechanisms for Pb（Ⅱ）and MB.BCGel’s mechanism for the adsorption of pollutants entails the interaction of multiple adsorption forms.BCGel’s exceptional Pb（Ⅱ）and MB adsorption capacities were due to its access to a large number of carboxyl groups;these groups were also responsible for BC₃Gel’s high capacity to adsorb other cationic dyes.