Oxidation has been profitably utilized to improve some properties of chitosan.However,only solventbased oxidation procedures have been proposed so far,which are hardly feasible at industrial scale in an economic way b...Oxidation has been profitably utilized to improve some properties of chitosan.However,only solventbased oxidation procedures have been proposed so far,which are hardly feasible at industrial scale in an economic way because of product recovery cost.In this study,a solvent-free,rapid,and effective oxidation method is proposed.It is based on direct solid-state reaction between chitosan and oxidant powder in a mechanochemical reactor.Results prove that by short high energy ball milling(<3 h)it is possible to achieve diverse physicochemical modifications employing different reagents.Apart from polysaccharidic chain shortening,persulfate provokes high amorphization and induces formation of ketonic groups;percarbonate heightens deacetylation degree,preserving in part crystallinity;calcium peroxide merely deprotonates amino groups and increases amorphization degree.Adsorption tests with the azo-dye reactive red 2 show that adsorption capacity of chitosan co-milled with persulfate(974 mg/g milled product),which is the best performing adsorbent,is twice that of pristine chitosan,while adsorption rate is outstandingly boosted(125 times).展开更多
Polymer thermal recycling for hydrogen production is a promising process to recover such precious element from plastic waste. In the present work a simple but efficacious high energy milling pretreatment is proposed t...Polymer thermal recycling for hydrogen production is a promising process to recover such precious element from plastic waste. In the present work a simple but efficacious high energy milling pretreatment is proposed to boost H2 generation during polyethylene gasification. The polymer is comilled with calcium and nickel hydroxides and then it is subjected to thermal treatment. Results demonstrate the key role played by the calcium hydroxide that significantly ameliorates hydrogen production. It reacts in solid state with the polyethylene to fonn directly carbonate and hydrogen. In this way, the CO2 is immediately captured in solid fonn, thus shifting the equilibrium toward H2 generation and obtaining high production rate (>25 L/mol CH2). In addition, high amounts of the hydroxide prevent excessive methane fonnation, so the gas product is almost pure hydrogen (~95%).展开更多
基金financially supported by the Major Science and Technology Program for Water Pollution Control and Treatment in China(No.2017ZX07202003)the National Key Research and Development Program of China(No.2018YFC1803100).
文摘Oxidation has been profitably utilized to improve some properties of chitosan.However,only solventbased oxidation procedures have been proposed so far,which are hardly feasible at industrial scale in an economic way because of product recovery cost.In this study,a solvent-free,rapid,and effective oxidation method is proposed.It is based on direct solid-state reaction between chitosan and oxidant powder in a mechanochemical reactor.Results prove that by short high energy ball milling(<3 h)it is possible to achieve diverse physicochemical modifications employing different reagents.Apart from polysaccharidic chain shortening,persulfate provokes high amorphization and induces formation of ketonic groups;percarbonate heightens deacetylation degree,preserving in part crystallinity;calcium peroxide merely deprotonates amino groups and increases amorphization degree.Adsorption tests with the azo-dye reactive red 2 show that adsorption capacity of chitosan co-milled with persulfate(974 mg/g milled product),which is the best performing adsorbent,is twice that of pristine chitosan,while adsorption rate is outstandingly boosted(125 times).
文摘Polymer thermal recycling for hydrogen production is a promising process to recover such precious element from plastic waste. In the present work a simple but efficacious high energy milling pretreatment is proposed to boost H2 generation during polyethylene gasification. The polymer is comilled with calcium and nickel hydroxides and then it is subjected to thermal treatment. Results demonstrate the key role played by the calcium hydroxide that significantly ameliorates hydrogen production. It reacts in solid state with the polyethylene to fonn directly carbonate and hydrogen. In this way, the CO2 is immediately captured in solid fonn, thus shifting the equilibrium toward H2 generation and obtaining high production rate (>25 L/mol CH2). In addition, high amounts of the hydroxide prevent excessive methane fonnation, so the gas product is almost pure hydrogen (~95%).
