Effects of Peracetic Acid(PAA) Combined with Calcium Treatments on Storage Quality of Loquat Fruit

[Objective] The paper was to evaluate effects of peracetic acid （PAA） combined with calcium treatments on storage quality of Ioquat fruits, so as to pro- vide practical techniques to solve the problems of postharvest rot and quality deteri- oration for Ioquat fruits. [Method] With Ioquat fruits of Qingzhong variety as materi- als, 0.2%, 0.4% and 0.8% PAA combined with 0.8% CaCI2 was used to soak Ioquat fruits for 4 min, 0.8% CaCl2 and water treatments were set as two controls; the fruits were dried and packaged by 0.02 mm PE bags, then stored under non-chilling low temperature of （7±1） ℃. The indicators related to storage quality of Ioquat fruits were randomly tested once every 3 d, and their variation situations were analyzed. [Result] Compared with two control treatments and 0.2% PAA, 0.8% PAA combined with calcium treatments, the treatment of 0.4% PAA combined with 0.8% CaCl2 could significantly inhibit rot index, weight loss rate, firmness and cell membrane permeability of Ioquat fruits during storage period, which could also effectively delay the reduction of titratable acid, vitamin C, soluble solid content and juice yield, and maintain respiration intensity of fruits at a low level; the appearance and flavor qual- ity of fruits were good after stored for 25 d. [Conclusion] 0.4% PAA combined with 0.8% CaCl2 treatment is an efficient, safe and economical practice technology in an- ti-corrosion and quality preservation for postharvest Ioquat fruits .

Fe^(2+)活化与电絮凝活化PAA对SMX的降解效果研究

文章选用磺胺甲恶唑(SMX)作为研究对象,考察电絮凝活化过氧乙酸(EC/PAA)降解SMX的效果,并对EC/PAA体系的缓冲能力及对SMX降解机理进行探究。结果表明:在初始pH值为7、电解质Na_(2)SO_(4)浓度为50 mmol/L、PAA浓度为10 mg/L、SMX浓度为3 mg/L、初始电流强度为60mA和极板间距为2cm的最佳实验条件下,EC/PAA体系20 min内能降解96%的SMX;溶液中共存的H_(2)O_(2)与PAA能够产生协同作用,协同系数SI达到30.125 0。在反应初始pH值为4~8时,反应结束后p H值均可缓冲至7左右,表明该体系具有很好的p H缓冲作用和电絮凝作用;而Fe^(2+)/PAA体系对SMX的降解主要是通过改变溶液pH值进行的,没有缓冲作用。经电子顺磁共振(EPR)鉴别,EC/PAA缓冲体系中的活性物种主要为羟基自由基(·OH)、有机自由基(CH_(3)COO·和CH_(3)COOO·)以及1O2,大部分为·OH,这些自由基共同作用将SMX降解。

Peracetic Acid Synthesis by Acetaldehyde Liquid Phase Oxidation in Trickle Bed Reactor

In this paper,shorter residence time（a few minutes）with high yield in the trickle bed process for per- acetic acid synthesis by acetaldehyde liquid phase oxidation can be realized on the selected packing material SA-5118.For acetaldehyde in acetone with ferric ion as catalyst,the optimized process conditions were presented. The main factors influencing the yield,selectivity and conversion are residence time,temperature and acetaldehyde concentration,respectively.The temperature range checked is from 30 to 65℃.High yield of 81.53%with high se- lectivity of 91.84%can be obtained at higher temperature of 55℃when the residence time is 5.5min and the acet- aldehyde concentration is 9.85%（by mass）.And there is a critical acetaldehyde concentration point（Cccp）between 18%and 19.5%（by mass）.At temperature less than 55℃,the highest yield to peracetic acid at each temperature level increases with temperature when the acetaldehyde concentration is below Cccp and decreases with temperature when the acetaldehyde concentration is above Cccp.

Encapsulated peracetic acid as a valid broad‑spectrum antimicrobial alternative,leading to beneficial microbiota compositional changes and enhanced performance in broiler chickens

Background Antimicrobial alternatives are urgently needed,including for poultry production systems.In this study,we tested the potential broad-range antimicrobial alternative peracetic acid,delivered in feed via the hydrolysis of encapsulated precursors through a 28-day study using 375 Ross 308 broiler chickens.We tested two peracetic acid concentrations,30 and 80 mg/kg on birds housed on re-used litter,and we evaluated the impact of both levels on gut microbial communities,bacterial concentration,antimicrobial resistance genes relative abundance and growth performance when compared to control birds housed on either clean or re-used litter.Results Body weight gain and feed conversion ratio improved in peracetic acid fed birds.At d 28,birds given 30 mg/kg of peracetic acid had a decreased Firmicutes and an increased Proteobacteria abundance in the jejunum,accompanied by an increase in Bacillus,Flavonifractor and Rombustia in the caeca,and a decreased abundance of tetracycline resistance genes.Chicken given 80 mg/kg of peracetic acid had greater caecal abundance of macrolides lincosamides and streptogramins resistance genes.Growth performance on clean litter was reduced compared to reused litter,which concurred with increased caecal abundance of Blautia,decreased caecal abundance of Escherichia/Shigella,Anaerostipes and Jeotgalicoccus,and greater gene abundance of vancomycin,tetracycline,and macrolides resistance genes.Conclusions Peracetic acid could be used as a safe broad-spectrum antimicrobial alternative in broilers.Encapsulated precursors were able to reduce the bacterial concentration in the jejunum whilst promoting the proliferation of probiotic genera in the caeca,especially at the low peracetic acid concentrations tested,and improve growth performance.Moreover,our findings offer further insights on potential benefits of rearing birds on re-used litter,suggesting that the latter could be associated with better performance and reduced antimicrobial resistance risk compared to clean litter rearing.

STUDY ON ELIMINATING FLUORESCENCE IN COTTON PULP WITH PERACETIC ACID

This paper has studied processing conditions and the influence of every variable to the pulp when the fluorescence in cotton linter pulp is eliminated with peracetic acid. The suitable variables of the elimination of fluorescence. are found.

Preparation of Peracetic Acid from Acetic Acid and Hydrogen Peroxide： Experimentation and Modeling

Based on the kinetic equations and equilibrium constants,some mathematic models were developed for calculating peracetic acid(PAA)concentration,equilibrium conversion rate of hydrogen peroxide,etc.The effects of several parameters on PAA synthesis were investigated by experimentation and modeling.The equilibrium constants determined from the forward and reverse rate constants at 293,303,313 and 323 K were 2.91,2.81,2.72 and 2.63,respectively.The models could predict the values of equilibrium concentration of PAA with average relative deviation of less than 10%.Both of the experimental and model-calculated results demonstrated that temperature and catalyst loading were the most important factors affecting the rate of PAA synthesis,but high temperature led to the decrease of equilibrium concentration of PAA.According to the model,the reaction could achieve equilibrium within 24 h when operated at 303 K with 1%～1.5%(ω)sulfuric acid as catalyst.Additionally,when using anhydrous acetic acid and 30%hydrogen peroxide to prepare PAA,the volumetric ratio of the two solutions should be in the range of 1.2～1.5 in order to obtain the highest equilibrium concentration of PAA.This study can serve as a step towards the further optimization of PAA synthesis and some other related investigations.

PASP、PAA与PBTCA阻垢性能的对比实验研究

采用静态阻垢法研究了聚天冬氨酸(PASP)、聚丙烯酸(PAA)和2-膦酸基丁烷-1,2,4-三羧酸(PBTCA)对碳酸钙和硫酸钙的阻垢性能,并用旋转挂片法研究了3种阻垢剂作用下湿法石灰脱硫浆液系统的结垢规律.研究发现:随着阻垢剂浓度的增加,3种阻垢剂都表现出溶限效应;相同实验条件下,3种阻垢剂对碳酸钙的静态阻垢性能表现为PBTCA>PAA>PASP;对中性和碱性环境,pH对阻垢剂阻硫酸钙垢的性能影响较小;随着温度的升高和反应时间的延长,3种阻垢剂阻硫酸钙的阻垢率先增大后减小;对湿法石灰脱硫浆液系统,3种阻垢剂作用下,单位面积挂片上的结垢量均是随着阻垢剂质量浓度的增大先增大后减小,在浓度达到30mg/L时,挂片上的结垢量都很小.

PAA／HB去除白钨矿选矿废水COD的研究

采用酸碱联用水处理工艺对选矿废水中的水玻璃进行混凝反应,消除了废水中悬浮物和重金属对选硫和选钨指标的影响。其次,利用聚丙烯酸/硫酸酸化膨润土(PAA/HB)复合物对混凝后选矿废水中的COD去除进行了研究。结果表明,经酸碱联用混凝沉淀后的澄清选矿废水1 L,在20℃下,吸附剂用量为1.0 g,pH=5.0,100 r/min振荡2 min时,处理效果最好,COD去除率最高达78.9%。处理后的废水可全部回用到磨矿、选硫及重选作业,真正实现了"零排放",达到了清洁生产的目的。

温度对α-Al_2O_3-H_2O-PAA悬浮液稳定性的影响

研究了温度对-αAl2O3-H2O-聚丙烯酸悬浮液分散稳定性的影响。研究表明:温度升高,粉体充分分散时所需的PAA添加量增大。浆料体系中分散剂添加量低于给定温度下的最佳添加量时,温度升高,浆料粘度增加,稳定性下降。但在适量聚丙烯酸(polyacrylic acid,PAA)分散剂存在的前提下,提高温度,可以显著降低高固含量浆料的粘度。

PVA/PAA/Fe3+超分子水凝胶的制备及其性能

为提高水凝胶的力学性能并扩展其应用,采用生物相容性良好的聚乙烯醇(PVA)、聚丙烯酸(PAA)为基质材料,以氢键和配位键为物理交联点,制备具有高力学性能的PVA/PAA/Fe^3+水凝胶;通过调节溶液中盐酸浓度、Fe^3+浓度和水凝胶浸泡时间研究其对水凝胶力学性能的影响,通过溶液的pH值探讨水凝胶的稳定性,通过循环加载-卸载实验评估水凝胶的自恢复性能。研究结果表明:红外光谱表征水凝胶网络结构氢键及配位键已形成;当溶液盐酸浓度为0.2 mol/L、Fe^3+浓度为0.09 mol/L、浸泡时间为20 h时,水凝胶力学强度最优,其拉伸强度为12.69 MPa,韧性为41.64 MJ/m3;将水凝胶做一次循环加载-卸载实验之后,静置240min,其应力、应变恢复率分别达到90%、87.8%。

Peracetic acid(PAA)-based pretreatment effectively improves medium-chain fatty acids(MCFAs)production from sewage sludge

Peracetic acid(PAA),known for its environmentally friendly properties as a oxidant and bactericide,is gaining prominence in decontamination and disinfection applications.The primary product of PAA oxidation is acetate that can serve as an electron acceptor(EA)for the biosynthesis of medium-chain fatty acids(MCFAs)via chain elongation(CE)reactions.Hence,PAA-based pretreatment is supposed to be beneficial for MCFAs production from anaerobic sludge fermentation,as it could enhance organic matter availability,suppress competing microorganisms and furnish EA by providing acetate.However,such a hypothesis has rarely been proved.Here we reveal that PAA-based pretreatment leads to significant exfoliation of extracellular polymeric substances(EPS)from sludge flocs and disruption of proteinic secondary structures,through inducing highly active free radicals and singlet oxygen.The production of MCFAs increases substantially to 11,265.6 mg COD L^(-1),while the undesired byproducts,specifically long-chain alcohols(LCAs),decrease to 723.5 mg COD L^(-1).Microbial activity tests further demonstrate that PAA pretreatment stimulates the CE process,attributed to the up-regulation of functional genes involved in fatty acid biosynthesis pathway.These comprehensive findings provide insights into the effectiveness and mechanisms behind enhanced MCFAs production through PAA-based technology,advancing our understanding of sustainable resource recovery from sewage sludge.

以TEA和PAA为分散剂的水基流延SDC

分别以三乙醇胺(TEA)和聚丙烯酸(PAA)为分散剂,用水基流延法制备Sm2O3掺杂的CeO2(Ce0.8Sm0.2O1.9,SDC)陶瓷,研究了pH值对SDCζ电位的影响,分析了SDC生坯的物理性能。TEA和PAA分散的SDC,最大ζ电位绝对值分别为62 mV和49 mV,TEA分散的生坯在基板上铺展得更好,外观更均一,显微结构更均匀、致密,TEA和PAA分散的生坯,相对密度分别为51.7%和46.2%,极限抗拉强度分别为1.25 MPa和1.06 MPa。TEA是SDC陶瓷较好的水基流延分散剂。

添加剂PAAS对锌镍电池负极性能的影响

分析了负极中添加聚丙烯酸钠（PAAS）对密封锌镍电池充放电性能及内阻的影响。PAAS可分散浆料并提高电极的润湿性,负极浆料的固含量可提高11%。添加PAAS制备的锌镍电池,放电平台电压高达1.670 V,循环寿命延长。当PAAS添加量为0.3%~0.5%时,电池以1.0C在1.400~2.100 V循环,第110次循环的容量保持率高于90%。

PAA-Na改性膨润土在酸碱盐溶液中的渗透性

针对高盐或强酸碱溶液中以膨润土为主材的防污屏障的阻控效果因膨润土膨胀性和抗渗性的降低而劣化的问题,采用聚丙烯酸钠(PAA-Na)对国产钠化钙基膨润土进行改性,提高膨胀性和防渗性.通过自由膨胀试验和改进滤失试验,研究不同浓度的NaCl溶液和酸碱溶液对聚丙烯酸钠改性膨润土PB2、PB5、PB10、PBHV5和美国怀俄明天然钠基膨润土的膨胀特性、渗透特性的影响规律.结果表明,在酸碱盐溶液中PB10的膨胀特性和渗透性优于怀俄明膨润土,PBHV5与怀俄明膨润土相近.pH=2的强酸条件和pH=12的强碱条件会降低PBHV5和PB10的膨胀性和抗渗性,pH=3~11的酸碱溶液对两者的影响很小.在酸碱溶液和低浓度(≤20 mmol/L)盐溶液中,由于晶层结构层剥离,3种膨润土渗透系数随着膨胀指数和孔隙比的增大而增大;在中高浓度(>20 mmol/L)盐溶液中,膨润土膨胀性降低,渗流通道增多,产生了渗透系数随膨胀指数和孔隙比的减小而增大的现象.在所研究的聚合物掺量(2%~10%)下,膨润土抗渗性和化学相容性随着聚合物掺量的增大而提高,若目标取得优于美国怀俄明天然钠基膨润土的特性,聚合物掺量须不低于5%.

A new multifunctional polymer:Synthesis and characterization of mPEG-b-PAA-grafted chitosan copolymer

A new multifunctional mPEG-b-PAA-grafted chitosan copolymer possessing amino and carboxyl groups,mPEG-b-PAA-g-CHI(compound 6) ,was designed for a potential application in gene/drug delivery and synthesized by the methods of reversible addition-fragmentation chain transfer(RAFT) polymerization of acrylic acid(AA) and grafting reaction of a biodegradable chitosan(CHI) derivative.Completion of the reactions and characterization of the resulting compounds were demonstrated by 1 H NMR,FTIR and gel permeation chtomatography(GPC) studies.The results show that the molar ratio of amino groups to carboxyl groups in the copolymer(compound 6) is 0.41-0.59.

Graft Polymerization of Acrylic Acid on a Polytetrafluoroethylene Panel by an Inductively Coupled Plasma

Surface modification on a polytetrafluoroethylene （PTFE） panel was performed with sequential nitrogen plasma treatments and surface-initiated polymerization. By introducing COO- groups to the surface of the PTFE panel through grafting polymerization of acrylic acid （AA）, a transparent poly （acrylic acid） （PAA） membrane was achieved from acrylic acid solution. Grafting polymerization initiating from the active group5 was achieved on the PTFE panel surface after the nitrogen plasma treatment. Utilizing the acrylic acid as monomers, with COO- groups as cross link sites to form reticulation structure, a transparent poly （acrylic acid） membrane with arborescent macromolecular structure was formed on the PTFE panel surface. Analysis meth- ods, such as fourier transform infrared spectroscopy （FTIR）, microscopy and X-ray photoelectron spectroscopy （XPS）, were utilized to characterize the structures of the macromolecule membrane on the PTFE panel surface. A contact angle measurement was performed to characterize the modified PTFE panels. The surface hydrophilicities of modified PTFE panels were significantly enhanced after the plasma treatment. It was shown that the grafting rate is related to the treating time and the power of plasma.

PVA-PAA共混／CA复合膜制备及其分离碳酸二甲酯的性能

研究了聚乙烯醇(PVA)、聚丙烯酸(PAA)共混膜的交联以及铸膜液配方和膜的热处理条件对PVA-PAA共混/CA复合膜渗透汽化(PV)分离碳酸二甲酯(DMC)/水混合物性能的影响.结果表明:交联的PVA-PAA膜在纯水中的溶解率小,改善了膜在长期运行中的稳定性;随着PAA含量、混合交联剂戊二醛和乙二醇的浓度以及热处理条件的变化,水渗透通量JH2O和渗透液的含水量CP-H2O呈规律性变化.在优化条件下制备的PVA-PAA共混/CA复合膜,PV分离DMC/水二元混合物的JH2O为100 g/(m2.h),CP-H2O接近100%,分离DMC/甲醇/水三元混合物时,可同时脱除甲醇和水,当操作温度升高,JH2O和JCH3OH分别增加,CP-DMC始终小于3.6%.

PAA为模板纳米SiO_2空心球及减反膜制备综述

纳米SiO_2空心球及其减反膜由于其独特的结构特点和优良的性能受到越来越多的关注,应用越来越广泛,纳米SiO_2空心球减反膜具有减反效果好、耐划伤、抗粘污、耐候性能优良等优点,使其在光学和太阳能光伏和光热等领域具有巨大的应用前景。文章简述了以PAA(聚丙烯酸)为模板的纳米SiO_2空心球的制备方法,从催化剂NH_3·H_2O(氨水)、模板PAA和SiO_2前驱体TEOS(正硅酸四乙酯)等3个方面分析了纳米SiO_2空心球制备过程中的影响因素,阐明了模板核PAA的去除原理及去除方法;阐述了纳米SiO_2空心球减反膜的制备技术,总结了纳米SiO_2空心球减反膜溶胶的制备方法和减反膜的镀膜方法,分析了烧结对减反膜的作用;并对纳米SiO_2空心球减反膜制备过程中存在的问题及其改善方法进行了展望。

Preparation and Properties of pH-Responsive Intelligent Medical Dressing Based on Bacterial Cellulose/Polyacrylic Acid

Bacterial cellulose/polyacrylic acid (BC/PAA) pH-responsive hydrogels were prepared by free-radical polymerization (in situ) using BC as the raw material and AA as the monomer. The hydrogels were loaded with curcumin (Cur) to prepare pH-responsive intelligent medical dressings. The preparation process of the hydrogels was optimized by a single factor and response surface experiment using their swelling degree as an index. The structures of BC/PAA pH-responsive hydrogels were characterized by scanning electron microscope (SEM), Fourier Transform Infrared spectrometer (FTIR), X-ray diffraction (XRD), and tensile tester, and the swelling properties, mechanical properties, bacteriostatic properties, and drug release behavior were investigated. The results showed that the BC/PAA pH-responsive hydrogel has a three-dimensional network structure with the swelling rate up to 1600 g/g, compressive strength of up to 8 KPa, and good mechanical properties, and the drug release behavior was in line with the logistic dynamics model, and it has good inhibitory effects on common pathogens of wound infection: E. coli, S. aureus, and P. aeruginosa.

铁离子配位聚丙烯酸基芬顿催化纤维的制备及其性能

为改善聚丙烯酸(PAA)纤维的性能,在湿法纺丝过程中基于铁离子配位反应成功制备了可拉伸PAA初生纤维,利用后拉伸以及热定型工艺优化纤维性能,并探究其作为Fenton催化剂在染料废水处理领域的应用。结果表明:相较硫酸铁盐,氯化铁盐配位的PAA纤维具有更为优异的力学性能和尺寸稳定性;后拉伸和热定型工艺可显著提高PAA纤维的力学性能和催化活性,并抑制铁离子的流失,拉伸20倍且在130℃定型的纤维断裂强度为1.42 cN/dtex,与未拉伸纤维相比提高了914.3%,且可在3 min内脱色90%以上的亚甲基蓝(MB),循环使用40次未出现脱色率衰减现象。