| Harmful pathogenic bacteria and viruses are ubiquitous in the environment where humans live.As people’s awareness of safety and hygiene gradually increases,the demand for antibacterial materials is also increasing.Among them,antibacterial film materials have a wide range of application prospects in the textile industry,food packaging,clinical treatment and other fields,while traditional plastic films will cause environmental pollution and resource shortage,in this context,the development of green,safe,stable,efficient and durable low-cost antibacterial materials has become a research hotspot.N-halamine antibacterial agent has many advantages such as high-efficiency broad-spectrum antibacterial,biofriendly and low cost,and meets the preparation needs of antibacterial materials.As a biomass resource with a wide range of sources,lignin has structural advantages and antibacterial,oxidation,shielding ultraviolet and other properties,and can be used as a reinforcing component of composite materials.In addition,lignin has the ability to adsorb a variety of pollutants,in the textile field,organic and inorganic pollutants in printing and dyeing wastewater cause serious harm and damage to humans and ecosystems,so the lignin-based antibacterial material for the adsorption treatment of dyes,heavy metal ions and other pollutants is very promising.Based on this,this study will use N-halamine compounds as antibacterial agents to prepare lignin-based antibacterial film materials and explore their properties and applications.Starting from the selection of film-forming substrates,using pure natural compound starch and green synthetic polymer material polyvinyl alcohol as film-forming substrates,selecting alkaline lignin as a performance-enhancing component,introducing suitable N-halamine compounds as antibacterial agents according to their respective structures and properties,exploring the film-forming process and conducting performance tests,optimizing the high-performance antibacterial film materials,and finally exploring its application possibilities in the textile dyeing and finishing industry.(1)Starch(ST)was used as a film forming material,and alkaline lignin(AL)was introduced to modify it,make up for the shortcomings of poor mechanical properties and water resistance stability of starch film,and introduce antibacterial and UV shielding functions.Starch/alkaline lignin(ST/AL)composite films with excellent UV shielding and antibacterial properties were successfully prepared using solution casting method,while improving the water resistance and toughness of the starch film.Adding 1-chloro-2,2,5,5-tetramethyl-4-imidazolinone(MC)as an antibacterial agent,the obtained antibacterial composite film(ST/AL-MC)showed excellent antibacterial effects,which could inactivate 80.65%of E.coli and 97.33%of S.aureus within 1 min of contact,and 99.99%of E.coli and S.aureus within 5min of contact;The composite film containing 10 wt%AL exhibited a fracture elongation of81.30%and a toughness of 1.07 MJ/m~3,which were increased by 342%and 89%respectively compared to pure starch film,and the ductility and toughness were greatly improved;With the introduction of AL,the composite film can shield almost 100%of the UVB(320-275 nm),UVC(275-200 nm),and UVA(400-320 nm)spectra;Thermogravimetric analysis showed that AL enhanced the thermal stability of the film.(2)The preparation of ST/AL-MC antibacterial film fully proved that AL could enhance the water resistance,thermal stability,and mechanical properties of composite materials,and also endowed the film with UV shielding function.However,due to the defects of the starch film itself,the water resistance of the composite film was still poor.On the basis of preserving the green degradability of the film forming substrate,polyvinyl alcohol(PVA)was selected as the film forming substrate,and a polyvinyl alcohol/alkaline lignin(PVA/AL)antibacterial blend film(AL-5-DPDMH-Cl)with excellent performance was successfully prepared by solution casting method.Adding 3-(2,3-dihydroxypropyl)-5,5-dimethylhydantoin(DPDMH)to the system,the film loaded with DPDMH exhibited excellent antibacterial properties after chlorination,killing 100%of E.coli and S.aureus within 5 minutes of contact;The introduction of AL made PVA/AL blend films exhibit ultra-high toughness.AL-5-DPDMH-Cl achieved a fracture toughness of 35.6 MJ/m3 and a fracture strain of 240%;The film can shield 100%of the UVB(320-275 nm)and UVC(275-200 nm)spectra and most of the UVA(400-320 nm)spectra;In addition,the moisture absorption and swelling resistance of the prepared antibacterial film was greatly reduced.(3)The preparation of composite materials using AL as a hard phase and PVA as a soft phase can obtain excellent toughness and ductility,but only mixing methods cannot provide strong adhesion,and the film has insufficient water resistance stability.In order to solve the problem of AL dissolution,a silane coupling agent was used as a crosslinking agent to prepare polyvinyl alcohol/alkaline lignin antibacterial crosslinked film KH-1-Cl.The prepared crosslinked film has excellent elongation at break,exhibits excellent ductility and toughness,and has a fracture strain of 651.9(±16.33)%;KH-1-Cl film has a rapid and efficient bactericidal performance,killing 99.99%of E.coli and S.aureus in only one minute of contact,and KH-1-Cl can still have antibacterial properties after five chlorination quenching cycles;KH-1-Cl film has excellent UV shielding performance while ensuring transparency;KH-1-Cl film successfully solved the problem of poor water-resistant firmness,with almost no dissolution of AL and good water resistance stability.(4)Through the above research,a highly effective antibacterial cross-linked film with good water resistance and mechanical properties was prepared.The cross-linked film was used to adsorb methylene blue dye(MB)and explore its application potential in the field of printing and dyeing wastewater treatment.At a p H of 12 and a temperature of 45°C,the maximum capacity of the cross-linked film to adsorb MB was expected to reach 833.33 mg/g;The adsorption behavior of MB onto crosslinked films was more consistent with quasi second order kinetics(R~2=0.9990)and Freundlich model(R~2=0.9943),and the adsorption is mainly controlled by chemical reactions;Thermodynamic analysis showed that adsorption was spontaneous and increasing temperature would promote adsorption;The crosslinked film has a certain cyclic adsorption performance,and the adsorption efficiency is above 75%after three cycles.The cross-linked film has good adsorption and recycling performance,and is expected to be applied to the treatment of dyeing wastewater. |
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