Chitosan stabilized nanoscale zero-valent iron(CS-NZVI)is a novel composite material with both reducing and adsorption ability,which can be used in the removal of metal ions and arsenates in water and the degradation of aromatic dyes.In this review,the main synthesis methods and characteristics of CS-NZVI were firstly introduced,followed by summarization on the mechanism and application research progress of CS-NZVI in treatment of heavy metal ions,arsenic ions,dye wastewater.Subsequently,the modification methods and application progress of chitosan modified CS-NZVI,metal catalyst modified CS-NZVI and composite modified CS-NZVI were reviewed.Finally,suggestions and prospects for optimizing the preparation process of CS-NZVI,broadening the application conditions and improving the material properties were put forward.
Glycosidically bound volatiles(GBVs)of fermented jujube juice was obtained by adsorption and elution with Amberlite XAD-2 resin.The release principles of GBVs was investigated via three separate treatments:β-D-glucosidase enzymolysis(38℃,48 h),acid hydrolysis(pH 1.0,40℃,4 d)and ultrasound treatment(280 W,20 min,50℃).The GBVs obtained was then identified by electronic nose and headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry(GC-MS),while the valuable aroma components were analyzed for odor activity value(OAV).The results showed that GBVs obtained from the three treatments exhibited significant difference in types and content.In number,a total of 16 aroma compounds were identified from GBVs with ultrasonic treatment,and acids were the most abundant aroma compound.A total of 21 aroma compounds,mainly including acids and other components,were identified from GBVs with acid hydrolysis,while 32 ones were identified with enzymolysis,mainly including esters,alcohols and acids.Damascenone and nonanal played a major role for the aroma of fermented jujube juice.The substances hydrolyzed by ultrasonic treatment and acid hydrolysis treatment were mainly acids of fermented jujube juice,while the esters,alcohols and aldehydes were the main aroma components with enzymolysis.Therefore,β-D-glucosidase enzymolysis treatment was more conducive to the release of many GBVs in fermented jujube juice.
Self-healing hydrogels have been widely used in electronic skin,flexible robots and wearable devices due to their excellent mechanical properties,good biocompatibility and extended material life.The structural adjustability and the diversity of conductive materials also provide the possibility for the synthesis of flexible sensors with different functions.Herein,self-healing hydrogels were classified according to the cross-linking mode,functional type,healing pattern and relative molecular mass of gelatinizer,with a detailed introduction on the formation mechanism and properties of each category self-healing hydrogels.Home and abroad research status of self-healing hydrogels in flexible sensors in terms of mechanics,photoelectricity and biology was reviewed.Finally,the existing problems and the future development directions were discussed.
In order to improve the organic matter degradation in biogas slurry and electricity production of microbial fuel cell(MFC),nano-Fe3O4 was combined with MFC via two different intervention methods by loading nano-Fe3O4 on anode carbon felt(Fe3O4@carbon felt)and loading nano-Fe3O4 on biochar(Fe3O4@biochar)into the anode chamber.The influence of these two intervention methods on the performance of MFCs were investigated.The results showed that MFC could be started by both methods,and exhibited much higher electrogeneration efficiency compared with MFC without nano-Fe3O4 intervention.The MFC treated with Fe3O4 showed maximum voltage of 699 and 707 mV,respectively,with the maximum voltage lasted up to 10 d.The maximum power density was increased by 43%in the Fe3O4@carbon felt(700 mW/m2)and 31%in the Fe3O4@biochar(578 mW/m2)in comparison to that MFC without Fe3O4 nanoparticles.The highest chemical oxygen demand(COD)degradation rate(51.76%)was obtained using Fe3O4@carbon felt as anode electrode.Direct application of Fe3O4@biochar showed the greatest effect on the degradation of NH4+-N,with degradation rate of 89.87%,the NH4+-N decreased from(6800.14±57.86)mg/L to(689.14±37.29)mg/L after the application of Fe3O4@biochar.The microbial community structure of the MFC with the participation of nano-Fe3O4 tended to be rationalized.Both participation methods stimulated the growth of the main hydrolytic bacteria(Clostridia).With the position of nano-Fe3O4 changing,the relative abundance of Clostridia in the MFC with Fe3O4@biochar directly inputting into the anode chamber and the MFC with Fe3O4@carbon felt as anode electrode reached to 61.11%and 50.98%,respectively.Both had the highest content of Betaproteobacteria in electroactivation and denitrifying bacteria Sporosarcina was found on the post-reaction carbon felt.
The number and variety of solid wastes have increased as a result of socioeconomic growth and human activity,and resourcization of solid wastes has become a hot research topic at home and abroad.There is significant room for improvement in waste resourcization in the context of dual carbon,which emphasizes the growth of the circular economy.Treatment of uranium(Ⅵ)-containing radioactive wastewater,produced by the nuclear industry with a rapid advancement of nuclear technology,with adsorbent materials made of solid waste could achieve the goal of"treating waste with waste",alleviate environmental pollution issues and facilitate sustainable development.Herein,main solid waste adsorbents,such as agricultural and forestry solid waste,industrial solid waste and municipal solid waste that can be used for uranium removal were summarized,followed by introduction on the synthesis and modification methods of solid waste adsorbents as well as uranium removal mechanism.Finally,it was pointed out that the uranium adsorption materials should be developed in the direction of high efficiency adsorption,environmental protection and high added value.
