纳米TiO2—两性淀粉对脱墨浆新闻纸抄造过程中DCS去除的研究

研究了两性淀粉（AmS）、纳米TiO2单元体系、纳米TiO2-AmS双元体系、阳离子淀粉（CS）／阳离子聚丙烯酰胺（CPAM）／阴离子聚丙烯酰胺（APAM）三元体系对全脱墨浆（DIP）的动态絮聚作用,并考察这几种助留助滤体系在白水循环使用情况下,对抄造纸页部分性能及白水中DCS去除效果的影响。动态絮聚实验表明：AmS单元体系几乎没有去除DCS的作用,增大用量还会使体系的DCS残留量更高;纳米TiO2单元体系有一定的DCS去除效果;TiO2-AmS双元体系不仅提高了DCS的去除效果,还降低试剂用量,当其用量为0．16％（TiO2）-0．4％（AmS）时,DCS的去除率达到50％以上;三元体系的助留助滤效果较好,但是DCS的去除效果一般。白水循环使用抄纸实验表明：纳米TiO2-AmS体系对残余油墨的捕集能力最强,对DCS的去除效果也最好,在白水循环抄纸进行到22次时,DCS的富集量达到平衡,白水离心处理后CODCr值为43mg／L左右,较好抑制了DCS的进一步富集;三元体系在循环进行到52次时,其离心处理后白水CODCr值稳定在65mg／L左右。     

纳米TiO2胶体多元复配体系对DIP的助留助滤研究

利用动态滤水实验,通过检测留着率和滤水时间来考察纳米TiO2胶体多元复配体系对脱墨浆(DIP)抄造新闻纸过程的助留助滤作用.结果表明,二元体系中,AmS(两性淀粉)-TiO2二元复配体系助留助滤效果最好,当纳米TiO2胶体用量0.20％和AmS用量0.5％时,其滤水时间是13s,其总留着率达到93.4％;在三元体系中,当CS(阳离子淀粉)用量0.4％、APAM(阴离子聚丙烯酰胺)用量0.01％和纳米TiO2胶体用量0.2％时的体系的滤水时间最小,为17s;当CS用量0.4％、CPAM(阳离子聚丙烯酰胺)用量0.01％和纳米TiO2胶体用量0.2％时总留着率最大,为97.5％.研究发现,纳米TiO2胶体多元体系具有好的助留助滤效果,淀粉系列因为具有三维结构,为纤维、DCS(溶解和胶体物质)的絮聚提供了更多的结合机会,而PAM(聚丙烯酰胺)系列主要通过桥联、电荷吸附以及补丁絮聚机理实现好的助留助滤效果.     

纳米TiO2胶体与改性淀粉双元体系的助留助滤效果

利用动态滤水(DDJ)实验,通过细小纤维单程留着率和滤水时间对纳米TiO2胶体与改性淀粉双元体系的助留助滤效果进行考察。研究该双元体系复配对纸张强度的影响及对白水循环中溶解和胶体物质(DCS)的除去与控制。结果表明,与阳离子淀粉(CS)相比,两性淀粉(AmS)与纳米TiO2双元体系有更好的协同作用,当淀粉用量不同、纳米TiO2用量约为0.4%时,细小组分单程留着率可增加5～12个百分点;纳米TiO2对AmS有正面的影响;AmS与纳米TiO2胶体复配对DCS的去除效果明显。     

纳米TiO_2-两性淀粉对脱墨浆抄造新闻纸的助留助滤作用

研究了纳米TiO2单元体系与纳米TiO2-两性淀粉(Amphoteric Starch,AmS)双元体系对脱墨浆(100%DIP)抄造新闻纸过程的助留助滤作用.结果表明,当采用纳米TiO2单元体系,其用量为0.32%(相对绝干浆)时,浆料滤液的相对浊度降为0.26,但其抗剪切能力较差;把纳米TiO2与AmS组成双元体系,用量分别为0.16%、O.4%时,浆料滤液的相对浊度为0.21,同时其抗剪切能力明显提高.在单独或复配使用纳米TiO2时,pH值5.0～9.0范围内有明显的助留助滤作用.通过测量浆料的Zeta电位变化,比较了双元体系不同加人位置时的助留助滤效果,研究了纳米TiO2对DCS的絮聚作用及其作用机理.     

新闻纸厂白水封闭循环对纸张抄造的影响

研究了新闻纸厂白水回用时DCS对聚乙烯亚胺(PEI)与阳离子聚丙烯酰胺(CPAM)、膨润土组成的三元微粒体系助留助滤效果的影响。结果表明,DCS能够降低CPAM的助留效果,但当加入PEI后,CPAM的助留效果可得到改善;随着白水循环回用次数的增加,助剂的助留助滤效果降低;当白水封闭到一定程度(80%)时,系统恶化,需新加入化学品以增强助剂的助留助滤效果。     

白水循环对新闻纸抄造的影响

研究新闻纸抄造系统不同循环次数的白水性质,以及白水中的溶解物质DCS对聚乙烯亚胺(PEI)、阳离子聚丙烯酰胺(CPAM)、膨润土组成的三元微粒助留助滤效果的影响。结果表明:随着循环次数的增加,白水性质变差,DCS的累积降低了CPAM的助留效果,助留助滤效果也随之降低。     

TiO2-沸石复合纸板制备中助留剂的作用

考察了TiO2-沸石复合纸板制备中聚二甲基二烯丙基氯化铵(PDADMAC)/阴离子聚丙烯酰胺(APAM)和阳离子淀粉/APAM二元助留体系助留效果。结果表明:PDADMAC/APAM二元助留体系对TiO2、沸石等无机物的助留效果显著,纸料和无机物的最高留着率分别达88.8%和83.0%。PDADMAC或APAM单元体系、阳离子淀粉/APAM二元助留体系的作用效果差。     

杨木P-RC APMP中溶解和胶体物质对湿部化学的影响

研究了溶解和胶体物质（DCS）对造纸湿部化学的影响。结果表明,DCS的加入能够降低单元助留助滤体系阳离子聚丙烯酰胺（CPAM）、双元助留助滤体系聚二甲基二烯丙基氯化铵（PDADMAC）/CPAM和微粒助留助滤体系CPAM/膨润土的助留助滤效果,并且能够使得不同助留助滤体系存在下的杨木P-RC APMP的Zeta电位下降。DCS的加入降低了阳离子助剂对滑石粉的絮聚程度,但随着DCS加入量的增加,阳离子助剂对碳酸钙的絮聚程度先下降后增加。同时,DCS的加入使得不同施胶剂的施胶效果变差。PDADMAC作为施胶促进剂对不同施胶剂或者含有不同DCS的浆料有一个最佳用量。     

凹凸棒黏土助留助滤效果研究

探讨了凹凸棒黏土与阳离子聚丙烯酰胺(CPAM)组成的微粒助留助滤体系的助留助滤效果及相关机理,并与CPAM-膨润土助留助滤体系进行了比较。结果表明,高剪切处理后的凹凸棒黏土微粒解聚分丝、具有更好的分散性能,提高了助留助滤效果。当凹凸棒黏土微粒用量为0.4%、CPAM用量为0.05%时,处理后的凹凸棒黏土助留助滤效果与商品膨润土相当,抄造纸张的强度性能略好。用聚焦光束反射原理测定絮体弦长及其分布发现,处理后凹凸棒黏土的絮体弦长大于未处理凹凸棒黏土的絮体弦长,但小于商品膨润土的絮体弦长。     

纳米TiO_2对造纸白水中DCS的除去与作用机理研究

造纸白水封闭循环是解决纸厂节约用水的有效途径之一,除去与控制白水中DCS是其关键技术。实验室模拟循环抄纸过程,应用常规助留助滤剂与纳米TiO2胶体及其二元复配助留助滤剂体系,测定白水中COD值,以其表征DCS浓度随着抄纸循环次数增加的变化规律,研究结果表明：当不使用或使用常规助留助滤剂时,白水中的DCS浓度随循环次数增加而增大;但当使用纳米TiO2胶体或其相应二元复合体系作为助留助滤剂时,白水中的DCS在初始阶段增加,随即达到稳定值。这一研究结果说明纳米TiO2胶体具有除去与控制白水中DCS的功能。纳米TiO2胶体对DCS溶液自动滴定作用机理研究显示,这一功能是通过吸附絮凝起作用的,絮凝过程并非电荷中和引起。     

纳米二氧化钛的制备及在造纸中的应用研究进展

本文阐述纳米二氧化钛在造纸中的应用研究进展。纳米二氧化钛具有正电性的表面,巨大的比表面积,尤其是单分散性优良的纳米二氧化钛胶体,在造纸过程中具有多方面的应用。包含纳米二氧化钛胶体的双元助留助滤体系可以除去与控制白水中的DCS,有利于实现造纸白水封闭循环,达到节能减排目的。纳米二氧化钛粒子有利于二次纤维中细小油墨粒子的浮选除去,并有效地提高胶黏物的除去效率。纳米二氧化钛的光催化活性在涂布纸的制造中也有潜在的应用,含纳米二氧化钛的涂布纸可以有效地降解空气中的有机污染物,并具有杀菌抗霉作用。造纸废水中的有机污染物均可以被纳米二氧化钛降解,包括生化法难处理的污染物,但是如果要实现工业化生产还需要更多地研究太阳光的利用与提高光催化效率。     

改性淀粉-TiO2体系对含不同填料的脱墨浆助留助滤效果研究

改性淀粉-TiO2体系作为助留助滤剂通过与含不同填料的脱墨浆作用,考察对浆料和填料的助留助滤效果。实验结果表明,改性淀粉-TiO2体系对浆料的留着以滑石粉为填料时最好,当两性淀粉(AmS)用量为0.4%、纳米TiO2用量为0.2%时,滑石粉为填料时总留着率达到91.8%,滑石粉留着率为94.3%;高岭土为填料时总留着率为87.8%,高岭土留着率为90.3%;钛白粉为填料时总留着率为87.3%,钛白粉留着率为91.1%;碳酸钙为填料时总留着率为81.4%,碳酸钙留着率为69.5%;滤水时间则是碳酸钙为填料时最少,为20 s,其次分别是滑石粉33 s、钛白粉48 s、高岭土53 s。     

Solid-state, planar photoelectrocatalytic devices using a nanosized TiO2 layer

Solid-state planar photoelectrocatalytic devices using a nanosized Ti02 layer have been fabricated and used in the photodegradation of gaseous formaldehyde (HCHO). It is discovered for the first time that in the photocatalytic degradation of HCHO over TiO2 film, besides a well-known process of exciton dissociation expressed as TiO2* --> e(-) + h+ (process A), there exists an HCHO-involved process of exciton dissociation expressed as TiO2 + HCHO* --> TiO2(-) + HCHO+ (process B); these two processes have comparable contributions to the electron photogeneration. A biased photocatalytic device is unable to photodegrade HCHO under the nitrogen condition, but under the air condition, a positive synergic effect of bias on the photodegradation of HCHO over the planar photoelectrocatalytic device has been observed, mainly attributed to it that the horizontal electric field can displace electrons generated via process B away from their counterparts, effectively suppressing hole-electron recombination on TiO2 surface and thereby leading to the enhanced formation of O2- species. The current research points out that the planar photoelectrocatalytic device can provide the in-depth investigations on the mechanisms of the photocatalytic degradation over nanosized semiconductor oxide films, and also have potential application in decomposing and mineralizing organic gas-phase pollutants.     

SERS detection of urea and ammonium sulfate adulterants in milk with coffee ring effect

In the current work, surface-enhanced Raman scattering (SERS) based on gold nanoparticles (AuNPs) and silver-coated gold nanoparticles (Au@AgNPs) with coffee ring effect was employed to simultaneously ascertain urea and ammonium sulfate (AmS) in milk. A small drop (2 µL) of milk with adulterants was dried on a gold-coated slide to examine concentrations ranging from 5, 10, 20, 40 and 80 mg/dL based on spectra ranging from 400 to 1500 cm.^?1 A uniform distribution of analytes, with enhanced Raman signals was detected in a small region (maximum 1.9 mm) of coffee ring across the centre of coffee ring pattern. Nanoparticles with core (Au) diameter of 26 nm and shell thickness (Ag) of 6.5 nm were confirmed using transmission electron microscopy (TEM) images. A strong Raman peak at 980 cm^?1 was assigned to AmS, while that at 1001 cm^?1 was ascribed to urea. With AuNPs, coefficients of determination (R²) of 0.9873 and 0.9859 were achieved for urea and AmS, respectively, while for Au@AgNPs values of 0.9827 and 0.9855 were obtained for urea and AmS, respectively. This study revealed that SERS based on coffee ring effect has the potential to be further exploited for detecting other banned and hazardous adulterants in milk and milk products.     

纳米TiO2/SiO2涂布颜料的制备及其喷墨打印性能的研究

用溶胶-凝胶法制备了纳米TiO2/SiO2复合材料,用扫描电子显微镜(SEM)、透射电子显微镜(TEM)和红外光谱(FT-IR)对其结构进行了表征。FT-IR光谱、TEM和SEM谱图分析表明,TiO2与SiO2基质之间存在着Ti—O—Si键,纳米TiO2/SiO2粒子形状基本为球形,粒径大小为20~50 nm。将纳米TiO2/SiO2复合材料用作喷墨打印涂布颜料,能够改善纸页平滑度、吸收性能、提高图像打印和印刷质量。     

Simultaneous and synergistic conversion of dyes and heavy metal ions in aqueous TiO2 suspensions under visible-light illumination

This study reports synergistic effects in the simultaneous conversion of dyes and heavy metal ions in aqueous TiO2/dye/metal ion systems (ternary components) under visible light (lambda > 420 nm). TiO2/Cr(VI)/Acid Orange 7 (AO7), TiO2/Cr(VI)/Rhodamine B (RhB), TiO2/Ag+/AO7, and TiO2/Ag+/RhB were chosen as test systems. Although dyes can be degraded in TiO2 suspensions under visible light, their removal rates were markedly enhanced in the presence of metal ions. Similarly, the reduction rates of metal ions in visible-light-illuminated TiO2 suspensions were negligible, but they were highly accelerated with dyes present. In particular, the synergistic effect in the ternary system of TiO2/Cr(VI)/AO7 was outstanding. The presence of dissolved oxygen increased the photoreduction rate of Cr(VI) despite the fact that Cr(VI) and O2 are competing electron acceptors. This is ascribed to in-situ photogenerated H2O2 from O2, which acts as a reductant of Cr(VI). RhB and Ag+ ions could be also converted simultaneously under visible light both in the presence and absence of TiO2. The visible-light-induced reduction of Ag+ did not occur at all in TiO2/Ag+ system, but it was enabled in both TiO2/Ag+/ RhB and TiO2/Ag+/AO7 to generate Ag particles. On the other hand, the binary systems of Cr(VI)/AO7, Ag+/AO7, and Ag+/RhB show significant visible-light activities for the conversion of both dye and metal ion. In this case, metal ions and dyes seem to form complexes that induce intracomplex electron transfers upon visible-light absorption. The Cr(VI)/RhB system, however, exhibited insignificant visible-light reactivity.