Conditioned medium from human dental pulp stem cells treats spinal cord injury by inhibiting microglial pyroptosis

Human dental pulp stem cell transplantation has been shown to be an effective therapeutic strategy for spinal cord injury.However,whether the human dental pulp stem cell secretome can contribute to functional recovery after spinal cord injury remains unclear.In the present study,we established a rat model of spinal cord injury based on impact injury from a dropped weight and then intraperitoneally injected the rats with conditioned medium from human dental pulp stem cells.We found that the conditioned medium effectively promoted the recovery of sensory and motor functions in rats with spinal cord injury,decreased expression of the microglial pyroptosis markers NLRP3,GSDMD,caspase-1,and interleukin-1β,promoted axonal and myelin regeneration,and inhibited the formation of glial scars.In addition,in a lipopolysaccharide-induced BV2 microglia model,conditioned medium from human dental pulp stem cells protected cells from pyroptosis by inhibiting the NLRP3/caspase-1/interleukin-1βpathway.These results indicate that conditioned medium from human dental pulp stem cells can reduce microglial pyroptosis by inhibiting the NLRP3/caspase-1/interleukin-1βpathway,thereby promoting the recovery of neurological function after spinal cord injury.Therefore,conditioned medium from human dental pulp stem cells may become an alternative therapy for spinal cord injury.

Self-assembly of differentiated dental pulp stem cells facilitates spheroid human dental organoid formation and prevascularization

BACKGROUND The self-assembly of solid organs from stem cells has the potential to greatly expand the applicability of regenerative medicine.Stem cells can self-organise into microsized organ units,partially modelling tissue function and regeneration.Dental pulp organoids have been used to recapitulate the processes of tooth development and related diseases.However,the lack of vasculature limits the utility of dental pulp organoids.AIM To improve survival and aid in recovery after stem cell transplantation,we demonstrated the three-dimensional(3D)self-assembly of adult stem cell-human dental pulp stem cells(hDPSCs)and endothelial cells(ECs)into a novel type of spheroid-shaped dental pulp organoid in vitro under hypoxia and conditioned medium(CM).METHODS During culture,primary hDPSCs were induced to differentiate into ECs by exposing them to a hypoxic environment and CM.The hypoxic pretreated hDPSCs were then mixed with ECs at specific ratios and conditioned in a 3D environment to produce prevascularized dental pulp organoids.The biological characteristics of the organoids were analysed,and the regulatory pathways associated with angiogenesis were studied.RESULTS The combination of these two agents resulted in prevascularized human dental pulp organoids(Vorganoids)that more closely resembled dental pulp tissue in terms of morphology and function.Single-cell RNA sequencing of dental pulp tissue and RNA sequencing of Vorganoids were integrated to analyse key regulatory pathways associated with angiogenesis.The biomarkers forkhead box protein O1 and fibroblast growth factor 2 were identified to be involved in the regulation of Vorganoids.CONCLUSION In this innovative study,we effectively established an in vitro model of Vorganoids and used it to elucidate new mechanisms of angiogenesis during regeneration,facilitating the development of clinical treatment strategies.

Human dental pulp stem/stromal cells in clinical practice

Dental pulp stem/stromal cells(DPSCs)are fibroblast-like,neural crest-derived,and multipotent cells that can differentiate into several lineages.They are relatively easy to isolate from healthy and inflamed pulps,with little ethical concerns and can be successfully cryopreserved and thawed.The therapeutic effects of DPSCs derived from animal or human sources have been extensively studied through in-vitro and in-vivo animal experiments and the findings indicated that DPSCs are effective not only for dental diseases but also for systemic diseases.Understanding that translational research is a critical step through which the fundamental scientific discoveries could be translated into applicable diagnostics and therapeutics that directly benefit humans,several clinical studies were carried out to generate evidence for the efficacy and safety of autogenous or allogeneic human DPSCs(hDPSCs)as a treatment modality for use in cell-based therapy,regenerative medicine/dentistry and tissue engineering.In clinical medicine,hDPSCs were effective for treating acute ischemic stroke and human exfoliated deciduous teeth-conditioned medium(SHED-CM)repaired vascular damage of the corpus cavernous,which is the main cause of erectile dysfunction.Whereas in clinical dentistry,autologous SHED was able to rege-nerate necrotic dental pulp after implantation into injured teeth,and micrografts enriched with autologous hDPSCs and collagen sponge were considered a treatment option for human intrabony defects.In contrast,hDPSCs did not add a significant regenerative effect when they were used for the treatment of post-extraction sockets.Large-scale clinical studies across diverse populations are still lacking to provide robust evidence on the safety and efficacy of hDPSCs as a new treatment option for various human diseases including dental-related problems.

Wnt pathway inhibitors are upregulated in XLH dental pulp cells in response to odontogenic differentiation

X-linked hypophosphatemia(XLH)represents the most common form of familial hypophosphatemia.Although significant advances have been made in the treatment of bone pathology,patients undergoing therapy continue to experience significantly decreased oral health-related quality of life.The following study addresses this persistent oral disease by further investigating the effect of DMP1 expression on the differentiation of XLH dental pulp cells.Dental pulp cells were isolated from the third molars of XLH and healthy controls and stable transduction of full-length human DMP1 were achieved.RNA sequencing was performed to evaluate the genetic changes following the induction of odontogenic differentiation.RNAseq data shows the upregulation of inhibitors of the canonical Wnt pathway in XLH cells,while constitutive expression of full-length DMP1 in XLH cells reversed this effect during odontogenic differentiation.These results imply that inhibition of the canonical Wnt pathway may contribute to the pathophysiology of XLH and suggest a new therapeutic strategy for the management of oral disease.

ON THE BLACK LIQUOR AND RECYCLE COOKING OF AS-AQ STRAW PULP

Thick black liquor, thin black liquor and solid state sodium hydroxide are added to the liquor treated by sulfur dioxide, then the blended liquor is used to recycle cooking of straw pulp. The black liquor, separated liquor and pulp of every cycles are analyzed respectively. Result shows that the content of lignin and organism in recycle black liquor and separated liquor increases faster in the first three cycles and then continues to increase slowly till four or five times, after that it trends to a stable state. The main organism separated from waste liquor of AS-AQ treated by sulfur dioxide is alkali-lignin, above 50% of total lignin in black liquor. The yield of pulp made from recycle cooking is steady, the hardness of pulp has a great improvement with recycle cooking. The brightness of pulp reduces correspondingly before bleaching, and after bleaching the brightness of pulp is relatively high and steady at the same sodium hypo chlorite dosage.

Co-Production of High-Grade Dissolving Pulp,Furfural,and Lignin from Eucalyptus via Extremely Low Acid Pretreatment and Pulping Technologies and Catalysis

Hemicellulose and lignin are not reasonably utilized during the dissolved pulp preparation process.This work aimed to propose a process for the co-production of dissolving pulp,furfural,and lignin from eucalyptus.High-grade dissolving pulp was prepared from eucalyptus using a combination of extremely low acid(ELA)pretreatment,Kraft cooking,and elementary chlorine-free(ECF)bleaching.The obtained pre-hydrolysate was catalytic conversion into furfural in a biphasic system,and lignin during Kraft cooking and ECF was recovered.The process condition was discussed as well as the mass flow direction.The results showed that ELA pretreatment could effectively remove 80.1%hemicellulose.Compared with traditional hydrothermal pretreatment,the ELA pretreatment significantly increased the xylose yield from 5.05 to 14.18 g/L at 170℃ for 2 h,which had practical significance for furfural production.The 82.7%furfural yield and 82.9%furfural selectivity were obtained from xylose-rich pre-hydrolysate using NaCl as a phase modifier in a biphasic system with 4-methyl-2-pentanone(MIBK)as an organic phase by ion exchange resin catalysts at 190℃ for 2 h.Subsequently,the pretreated eucalyptus was subjected to Kraft cooking,and the optimal alkali amount was 14%.Then,the Kraft pulp was bleached using the O-D1-EP-D_(2) sequence,and dissolving pulp was obtained with an ISO brightness of 86.0%,viscosity of 463 mL/g,andα-cellulose content of 95.4%.The Kraft lignin which has a potential application was investigated by 2D-HSQC NMR and 31P NMR.The results showed that the S/G ratio of Kraft lignin was 1.93,and the content of phenolic hydroxyl groups was 2.53 mmol/g.Moreover,based on the above proposed process,30.5 g dissolving pulp,5.5 g furfural,and 21.2 g lignin per 100 g eucalyptus chips(oven dry)were produced.This research will provide new catalysis and pulping technical routes for dissolving pulp,furfural,and Kraft lignin products,which are in great demand in the chemical industry.

Genetic modification of miR-34a enhances efficacy of transplanted human dental pulp stem cells after ischemic stroke

Human dental pulp stem cells(hDPSCs) promote recovery after ischemic stro ke;however,the therapeutic efficacy is limited by the poor survival of transplanted cells.For in vitro expe riments in the present study,we used oxygen-glucose deprivation/reoxygenation in hDPSCs to mimic cell damage induced by ischemia/reperfusion.We found that miRNA-34a-5p(miR-34a) was elevated under oxygen-glucose deprivation/reoxygenation conditions in hDPSCs.Inhibition of miR-34a facilitated the prolife ration and antioxidant capacity and reduced the apoptosis of hDPSCs.Moreove r,dual-luciferase reporter gene assay showed WNT1and SIRT1 as the targets of miR-34a.In miR-34a knockdown cell lines,WNT1 suppression reduced cell prolife ration,and SIRT1 suppression decreased the antioxidant capacity.Togethe r,these results indicated that miR-34a regulates cell prolife ration and antioxidant stress via targeting WNT1 and SIRT1,respectively.For in vivo expe riments,we injected genetically modified hDPSCs(anti34a-hDPSCs) into the brains of mice.We found that anti34a-hDPSCs significantly inhibited apoptosis,reduced cerebral edema and cerebral infarct volume,and improved motor function in mice.This study provides new insights into the molecular mechanism of the cell prolife ration and antioxidant capacity of hDPSCs,and suggests a potential gene that can be targeted to improve the survival rate and efficacy of transplanted hDPSCs in brain after ischemic stroke.

Biodegradation Behavior of Starch in Simulated White Water System of Old Corrugated Cardboard Pulping Process

Considering the serious barriers/issues induced by the accumulated starch generated in white water system of old corrugated cardboard(OCC)pulping process,large amounts of accumulated starch in white water would be decomposed by microorganisms and could not be utilized,thereby resulting in severe resource wastage and environmental pollution.This study mainly explored the effects of biodegradation/hydrolysis conditions of the two types of starch substrates(native starch and enzymatically(α-amylase)hydrolyzed starch),which were treated via microorganism degradation within the simulated white water from OCC pulping system and their biodegradation products on the key properties were characterized via X-ray diffraction(XRD),Fourier-transform infrared spectroscopy(FT-IR),and gel permeation chromatography(GPC)technologies.The effects of system temperature,pH value,starch concentration,and biodegradation time on starch biodegradation ratio and the characteristics of obtained biodegradated products from the two types of starches were studied.In addition,the effect ofα-amylase dosage on the biodegradation ratio of enzymatically hydrolyzed starch and its properties was investigated.It was found that the native starch presented a maximal degradation ratio at a system temperature of 55℃and pH value range of 5-7,respectively,the corresponding starch concentration within simulated white water system was 200 mg/L.Whereas the enzymatically hydrolyzed starch exhibited a highest degradation ratio at a system temperature of 50℃and pH value of 5.5,respectively,and the corresponding starch concentration within simulated white water system was 100 mg/L.It was verified that native starch is more readily bio-hydrolyzed and biodegradation-susceptive by microorganisms in simulated white water system of OCC pulping process,while the enzymatically hydrolyzed starch exhibits better biodegradation/hydrolysis resistance to the microbial degradation than that of native starch.This study provides a practical and interesting approach to investigate the starch hydrolysis or biodegradation behaviors in white water system of OCC pulping process,which would greatly contribute to the full recycling and valorized application of starch as a versatile additive during paperboard production.

Extracellular matrix remodelling in dental pulp tissue of carious human teeth through the prism of single-cell RNA sequencing

Carious lesions are bacteria-caused destructions of the mineralised dental tissues,marked by the simultaneous activation of immune responses and regenerative events within the soft dental pulp tissue.While major molecular players in tooth decay have been uncovered during the past years,a detailed map of the molecular and cellular landscape of the diseased pulp is still missing.In this study we used single-cell RNA sequencing analysis,supplemented with immunostaining,to generate a comprehensive single-cell atlas of the pulp of carious human teeth.Our data demonstrated modifications in the various cell clusters within the pulp of carious teeth,such as immune cells,mesenchymal stem cells(MSC)and fibroblasts,when compared to the pulp of healthy human teeth.Active immune response in the carious pulp tissue is accompanied by specific changes in the fibroblast and MSC clusters.These changes include the upregulation of genes encoding extracellular matrix(ECM)components,including COL1A1 and Fibronectin(FN1),and the enrichment of the fibroblast cluster with myofibroblasts.The incremental changes in the ECM composition of carious pulp tissues were further confirmed by immunostaining analyses.Assessment of the Fibronectin fibres under mechanical strain conditions showed a significant tension reduction in carious pulp tissues,compared to the healthy ones.The present data demonstrate molecular,cellular and biomechanical alterations in the pulp of human carious teeth,indicative of extensive ECM remodelling,reminiscent of fibrosis observed in other organs.This comprehensive atlas of carious human teeth can facilitate future studies of dental pathologies and enable comparative analyses across diseased organs.

Advances in Research of Molded Pulp for Food Packaging

The molded pulp,a product of three-dimensional papermaking technology,is environmentally friendly and has a low environmental impact due to its ability to decompose quickly in the natural environment after disposal.The application of molded pulp for food packaging can replace or reduce the use of plastic food packaging.Researchers extract fibers from plants for the production of safe and hygienic molded pulp for food packaging,and they also study and enhance the qualities of molded pulp to broaden its use in the food industry.This paper reviews the sources and varieties of plant fiber used in molded pulp for food packaging,as well as research on the improvement and optimization of the performance of molded pulp products.Additionally,issues with molded pulp’s actual use for food packaging are reviewed,along with the potential for future research.This work can serve as a reference for molded pulp applications and research in the food industry in the future.

High Performance of Paper Strength and Energy Savings in OCC Pulp Papermaking via MFC Addition

Fiber screen fractionation of recycled old corrugated container(OCC)pulp and subsequent targeted processing of each fraction can lead to higher fiber quality,more uniform pulp,and increased handsheet strength and surface smoothness.This pilot-scale study evaluates the benefits of fiber fractionation using a pressure screen prior to low consistency(LC)refining.A 0.81-mm smooth holed screen cylinder is utilized,and two refiner plate patterns are adopted(wide 0.99 km/rev BEL and interim 2.01 km/rev BEL).Here,LC-refined reject fractions are mixed with the created microfibrillated cellulose(MFC),and the mixed pulp and paper qualities are compared with no-MFC OCC pulps.The results indicate that the highest tensile strength of the handsheet is obtained by the addition of MFC to the fractionated refined OCC pulp compared to the unfractionated refined OCC and primary OCC pulps at a given specific energy.Furthermore,the experimental approach adopted in this study can be used to optimize recycled OCC pulping systems.Overall,the results indicate that fractionated LC refining plus MFC addition provides higher pulp and paper qualities and the potential for saving energy to reach the desired tensile strength of the OCC pulp.

Optimization of Intermittent Variable Power Microwave Heating Process for Blueberry Pulp

To improve heating uniformity and anthocyanin content of the blueberry pulp under microwave heating,the intermittent variable power microwave heating technology was introduced in the study.The effects of technology parameters in terms of high microwave intensity heating time,intermittent time,low microwave intensity and low microwave intensity heating time on the blueberry pulp quality parameters(heating uniformity,average moisture content,the highest temperature and anthocyanin content)were investigated by using the response surface method.The results showed that the longer heating time under different microwave intensities resulted in the poorer heating uniformity.The intermittent stage promoted heat and mass transfer within the pulp and reduced the temperature difference and moisture gradient within the pulp,which enhanced desired uniformity of temperature and moisture distribution before entering the low microwave intensity heating stage.Therefore,the longer the intermittent time,the greater the heating uniformity.The optimal parameters were developed as high microwave intensity of 4 W·g^(-1),high microwave intensity heating time of 9.86 min,intermittent time of 10 min,low microwave intensity of 2.2 W·g^(-1)and low microwave intensity heating time of 6 min.This research might provide guidance for microwave heating berry fruits.

Potential of dental pulp stem cells and their products in promoting peripheral nerve regeneration and their future applications

Peripheral nerve injury(PNI)seriously affects people’s quality of life.Stem cell therapy is considered a promising new option for the clinical treatment of PNI.Dental stem cells,particularly dental pulp stem cells(DPSCs),are adult pluripotent stem cells derived from the neuroectoderm.DPSCs have significant potential in the field of neural tissue engineering due to their numerous advantages,such as easy isolation,multidifferentiation potential,low immunogenicity,and low transplant rejection rate.DPSCs are extensively used in tissue engineering and regenerative medicine,including for the treatment of sciatic nerve injury,facial nerve injury,spinal cord injury,and other neurodegenerative diseases.This article reviews research related to DPSCs and their advantages in treating PNI,aiming to summarize the therapeutic potential of DPSCs for PNI and the underlying mechanisms and providing valuable guidance and a foundation for future research.

Effect of Refiner Plate Bar Angle and Pulp Properties on the Low Consistency Refining Efficiency in Terms of Power Consumption

Power consumption is the energy source of the impact on fibers or pulp during low-consistency(LC)pulp refining,and the strength of refining affects refining quality and efficiency.The pulp properties,operating parameters,and bar parameters of the refiner plates are important parameters affecting refining efficiency,which can be defined as the ratio of net to total refining power.In this study,LC refining trials for pulps with different consistencies and fiber lengths were conducted using five isometric straightbar plates with different bar angles to explore the influences of the plate bar angle and pulp properties on the no-load power,impact capacity on fibers and refining efficiency.It was found that the no-load power of the LC refining process decreased with an increase in the plate bar angle while increased when pulp with higher consistency was refined under the same refining conditions.However,the effect of pulp consistency on the no-load power can be neglected when refining is conducted using plates with larger bar angles.Meanwhile,a critical bar angle for straight-bar plates in LC refining may exist,which has the strongest impact on the pulp and highest refining efficiency under the same refining conditions.In addition,the impact capacity of the plate on the pulp and refining efficiency in LC refining can be enhanced by appropriately increasing the pulp consistency and average fiber length when the bar angle of the refiner plate with a sector angle of 40°is less than 30°.Therefore,the efficiency and power consumption of the LC refining process can be adjusted by optimizing the pulp consistency and bar parameters of the refining plates.

Effect of incorporation of raphia palm fruit pulp powder on the physicochemical, functional and sensory properties of biscuits

Background:Raphia fruit pulp is a good source of phytochemicals and some micronutrients and is locally consumed as a snack.The aim of this study was to valorize raphia pulp in biscuits production by partially substituting wheat flour in different proportions with flour obtained from the pulp of the raphia fruit.Methods:Ripe raphia(Raphia hookeri)fruits were purchased from local farms,thoroughly washed and the pulps extracted using a stainless-steel knife.These pulps were dried at 60℃for 12 h and grounded into flour.Wheat flour was substituted with the raphia pulp flour(RF)in five different proportions(10,20,30,35,and 40%).The functional properties and nutrient profile of the raphia flour and the biscuits obtained from these composite flours were evaluated.Sensory evaluation of the biscuits was also carried out using a nine-point hedonic scale.Results:The RF has a high-water absorption capacity WAC(680%)and oil absorption capacity OAC(560%)favoring its use in pastry processes.The RF is rich in polyphenols 435.0±20(μg/100g),saponins(155±5 mg/100g)and potassium(922±20 mg/100g).The incorporation of the RF in biscuits significantly affect the chemical composition.The total polyphenols increased from 182±10μg/100g in the sample containing 10%of RF to 342±17μg/100g in the sample containing 40%of RF.Fibers increased from 8.75±0.03 mg/100g in the sample with 10%of RF to 10.08±0.27 mg/100g in the 40%substituted biscuit.Saponins increased from 69.9±0.01 mg/100g in the sample with 10%of RF to 90.22±0.01 mg/100g in the sample with 40%RF and potassium increased from 434.2±10 mg/100g in the sample with 10%of RF to 647.6±5 mg/100g in the sample with 40%of RF.Biscuit samples made with composite flour containing 20%of RF was the most accepted.Conclusion:RF can be used as a raw material to replace 20%of wheat flour in biscuit formulations and improve its nutritional and sensory properties.

桉木化学机械浆废水好氧生物抑制特性分析及降解规律研究

采用GC-MS方法分析了桉木化学机械浆废水厌氧处理和好氧处理出水的有机物成分及含量,统计了好氧处理前后废水中碳原子数的分析情况,分析了废水中主要的生物难降解组分及降解规律。研究结果表明:经厌氧和好氧处理后残余的主要有机污染物为芳樟醇(C10,21.21%)、对叔丁基苯乙酸甲酯(C13,21.39%)、二氢月桂烯醇(C10,8.90%)、铃兰醛(C14,6.16%)和香茅醇(C10,4.76%)等,主要为含苯环有机物和抑菌成分,具有生物难降解性和抑菌性,宏观表现为生物处理去除率较低。好氧处理前后,废水中醇类物质质量分数从19.32%上升至51.71%,醛类物质质量分数从3.68%上升至13.35%,酯类物质质量分数从29.75%降至28.32%,含苯环有机物质量分数从32.70%上升至61.06%,说明其他有机物获得比含苯环有机物更大幅度的降解。建议通过解毒预处理和生物强化提高微生物活性等途径改善生物处理效果,减轻后续深度处理的难度,降低综合处理成本,实现低成本达标排放。

MTA与iRoot BP Plus行直接盖髓术治疗龋源性露髓恒磨牙临床疗效分析

目的:观察成熟恒磨牙去龋未净时露髓使用无机三氧化物聚合体(Mineral trioxide aggregate,MTA)和生物陶瓷类材料(iRoot BP Plus)行直接盖髓术的临床疗效,探讨此类术式的可行性及其影响因素,比较两种盖髓剂疗效的差异。方法:选取2018年4月-2019年10月就诊于笔者科室符合纳入标准的53例患者,共53颗患牙,随机分为M组和B组,分别使用MTA与iRoot BP Plus行直接盖髓术,术后定期复查,比较两组的临床疗效。结果:共计45例患者(45颗患牙)完成2年随访,总体成功率84.4%;M组和B组分别为85.7%、83.3%,两组比较差异无统计学意义(P>0.05)。性别、年龄、露髓孔大小等因素对疗效均无显著影响(P>0.05)。结论:成熟恒磨牙术中露髓时使用MTA或iRoot BP Plus行直接盖髓术均可获得良好疗效;相较于性别、年龄、露髓孔大小等因素,如何简单准确评判牙髓状态及避免龈下微渗漏更加值得关注。

预浸渍溶出物对巨尾桉机械浆漂白性能的影响

以巨尾桉热磨机械浆为研究对象,研究了3种化学品用量下(氢氧化钠10 kg/t、氢氧化钠30 kg/t、氢氧化钠10 kg/t+过氧化氢30 kg/t),3种预浸渍溶出物保留工艺对后续浆料漂白性能的影响。利用元素分析及裂解气质联用,比较了3种预浸渍溶出物的化学结构。结果表明,预浸渍处理浆的漂白性能均比桉木单段漂浆料漂白性能有较大提升,不同化学品用量预浸渍处理产生的预浸渍溶出物,在不同保留程度下,会对后续浆料的漂白性能有不同程度的负面作用。浆料中氮元素的溶出程度与浆料后续漂白性能的提升具有一定关联性。

雪莲菌发酵提高枸杞原浆甜菜碱含量的工艺优化及品质分析

该研究以混合菌种雪莲菌为发酵菌种,枸杞原浆中甜菜碱含量为指标,通过单因素试验和正交试验对雪莲菌发酵枸杞原浆进行工艺优化,并对发酵后的枸杞原浆进行品质分析。结果表明,最佳发酵工艺条件为雪莲菌接种量5%(m/V),发酵时间48 h,发酵温度25℃,此条件下甜菜碱含量为18.95 mg/mL,比未发酵枸杞原浆甜菜碱含量增加2.54倍,总酚含量为2.03 mg/mL、黄酮含量为0.68 mg/mL、总糖含量为11.92 mg/mL。雪莲菌发酵后枸杞原浆中共检测出65种挥发性成分,包括21种醇类、27种酯类、1种醛类、1种酮类、8种酸类、3种烷类、2种酚类和2种烯类,与发酵前相比新增24种,且醇类、酯类和酸类物质较发酵前显著性增加,挥发性成分总含量由8.94 mg/mL增加至39.76 mg/mL,为制备高品质枸杞原浆提供理论依据,为枸杞产业化深加工提供指导。

过氧化氢漂白过程中慈竹机械浆发色基团演变及溶出机制

在常规工艺下难以制备高白度(>78%)竹材化学机械浆是制约竹类资源在高附加值纸产品领域规模化应用的关键技术瓶颈。使用乙醇-水二元介质碱性过氧化氢漂白体系可以突破当前慈竹机械浆漂白上限,将纸浆白度提升至80%以上。以慈竹机械浆为原料,对比研究了常规过氧化氢用量(90 kg/t)水相体系两段漂工艺、高过氧化氢用量(180 kg/t)水相四段漂工艺和高过氧化氢用量(180 kg/t)乙醇-水二元介质相四段漂工艺中各段处理所得纸浆的发色基团结构特点,以及3种工艺漂白段溶出物的结构特点,以此探索二元体系漂白过程中发色基团形成和溶出规律。结果表明,在漂白过程中,慈竹机械浆中的苯环类共轭结构含量逐渐降低,但在化学品用量较大的漂白段会生成在水相体系无法被破坏和溶出的呋喃类共轭结构。在漂白体系中引入乙醇,可以显著提高呋喃类共轭结构的溶出效率,同时发现浆料中溶出的部分苯环结构发生了开环反应,推测碱性条件下乙醇电离的微量乙氧根离子对呋喃类共轭结构的脱除具有关键性作用。慈竹机械浆发色基团演变及溶出机制可为开发经济上可行的竹类机械浆漂白工艺提供理论基础。