合成聚合物改性TiO2及对加填纸主要性能的影响

采用3种合成聚合物(PDADMAC、PVAm和PNVF)分别对TiO₂进行改性,并用球磨机进行机械研磨,将改性后的TiO₂作为填料用于装饰原纸的抄造中,探究了不同改性剂用量下获得的改性TiO₂对加填后装饰原纸主要性能的影响。结果表明：改性剂PDADMAC用量为2.5%进行TiO₂改性时,与未改性TiO₂加填纸相比,改性TiO₂加填纸的抗张指数和填料留着率分别提高了21.0%和9.5%;PVAm用量为2.0%时,改性TiO₂加填纸的抗张指数和填料留着率比未改性TiO₂加填纸分别提高了24.7%和5.5%;PNVF用量为1.5%时,改性TiO₂加填纸强度性能和填料留着情况较优。     

水热预处理过程中pH值对玉米秸秆水解特性的影响

本研究采用乙酸或NaOH调节水热预处理的pH值,通过分析玉米秸秆中纤维素、半纤维素和木素降解产物的变化,研究了水热预处理的pH值对玉米秸秆水解特性的影响。结果表明,在水热预处理过程中,乙酸的添加促进了纤维素和半纤维素降解,但木素溶出率略有下降,水解液中木糖、低聚木糖、葡萄糖等糖类物质含量增加,糠醛和5-羟甲基糠醛等物质含量快速提升;当NaOH用量小于3%时,随着NaOH用量增加,纤维素和半纤维素降解减少,NaOH主要消耗于半纤维素中的乙酰基脱除;当NaOH用量为3%时,此时水热预处理终点pH值为5.84,固体物料得率达到最大值为75.15%;继续增加NaOH用量,木素的溶出率开始增加,固体物料得率下降。结果显示pH值可以成为调控水热预处理水解效果的重要手段。     

TPA/TiO2-SiO2的制备及在地沟油预酯化工艺中的应用

以钛酸丁酯和硅酸乙酯为原料制备TiO₂-SiO₂,以磷钨酸(TPA)为活性组分,通过浸渍法制备TPA/TiO₂-SiO₂,用于高酸值地沟油中的预酯化研究。TPA/TiO₂-SiO₂表征结果表明,TPA/TiO₂-SiO₂具有较好的热稳定性、内部存在孔结构、具有较大的比表面积。以地沟油的酸值变化率为指标,通过单因素试验和正交试验,确定最佳工艺条件：TPA负载量为40%,载体焙烧温度为600 ℃,催化剂用量为5 wt%,反应时间为5 h,醇油质量比为0.8:1。在此条件下,FFAs的转化率可以达到98%。     

加填对高得率浆性能的影响

探讨了分别加填TiO₂和CaCO₃对漂白高得率浆成纸强度性能和光学性能的影响。加填后,成纸抗张强度、耐破度和层间结合强度均有不同程度的降低。与CaCO₃加填纸相比,TiO₂加填纸的强度性能降低幅度较小。加填TiO₂可显著提高纸张的白度、不透明度和光散射系数。加填纸光散射系数相同时,TiO₂用量仅为CaCO₃用量的1/4。加填TiO₂可显著抑制高得率浆光诱导返黄,并且随其留着量的增加,抑制效果增强;TiO₂留着量为21.4%,加填纸光诱导返黄程度降低76.4%。加填CaCO₃对漂白高得率浆的光诱导返黄的抑制作用较小。     

漆酶协同活性炭处理脱除桉木预水解液中木素的研究

为了脱除桉木预水解液中的小分子木素,采用漆酶协同活性炭处理方法,对经过Ca(OH)_2和活性炭分别处理过的二级桉木预水解液进行脱木素处理,探讨漆酶处理过程中p H值、处理温度、漆酶用量和处理时间对木素脱除效率的影响。采用单因素实验结合响应面法对上述主要因素进行了模型分析与验证,建立了小分子木素脱除的数学模型。结果表明,经过漆酶处理后的二级处理液,其木素脱除率比未用漆酶处理的提高了12. 8个百分点。二级处理液中木素脱除率的4个因素影响大小的顺序为:p H值漆酶用量处理温度处理时间。漆酶协同活性炭处理的较优工艺条件为:p H值为5. 23、处理温度45. 3℃、漆酶用量5. 68 U/g (相对于处理液质量)、处理时间190 min,此条件下二级处理液中木素脱除率的预测值为65. 1%,实际测定平均值为65. 1%,木素脱除率为桉木预水解液所含木素的90. 5%。     

木素对木质纤维超临界水解性能的影响研究

本文针对木质纤维化学组成和结构特性,研究了木素对木质纤维化学组分、化学基团和结晶结构的影响,以及其中纤维素和半纤维素水解性能的影响。结果表明:木质纤维经碱处理脱除木素后,纤维氢键增强,结晶度由52.64%增至63.73%,使得晶区可反应表面积减少,表现在纤维水解性能方面是,最大水解率由75.4%增加至86.8%,己糖最大得率由17.79%降至6.07%,木糖最大得率由6.82%降至3.37%,5-羟甲基糠醛最大得率由12.7%降至8.48%,但到达己糖最大得率的时间由110s缩短至40s,水解液中酚、脂、酸等含有苯环的物质种类明显减少。     

纳米TiO2胶体絮凝-光催化氧化-砂滤深度处理造纸废水研究

研究了纳米TiO₂胶体絮凝-光催化氧化-砂滤深度处理造纸废水的效果。分析了絮凝剂的选择和用量、光催化剂用量、光催化时间和外加氧化剂等对废水COD_Cr去除效果的影响;研究证实了样品中残留微量纳米TiO₂胶体对COD_Cr测定的影响,并利用砂滤除去。实验结果表明,以用量为0.01%(相对于废水质量,下同)的纳米TiO₂胶体为絮凝剂对经序列间歇式活性污泥法（SBR）处理后的造纸废水进行处理,在光催化剂用量（质量分数）0.05%,曝气并紫外光照射2 h时,沉降后的上层液体经过砂滤,废水COD_Cr从210 mg/L降到43.0 mg/L。     

大麦醇溶蛋白/纳米TiO2可食性膜的制备与理化性质研究

本文以实验室自制的大麦醇溶蛋白为基材,以纳米TiO₂粒子为改性材料制备了可食性膜,并对其部分理化特性进行了深入研究。FTIR结果表明自制的蛋白粉在1654cm_-1、1545cm_-1及1452cm_-1处呈现典型的蛋白特征峰吸收;凯氏定氮结果表明其中蛋白含量高达92.63%;SDS-PAGE结果显示所制备的大麦醇溶蛋白主要包括大麦醇溶蛋白B组分(hordein B)及C组分(hordein C)。利用溶液浇铸法制备了大麦醇溶蛋白可食性膜以及大麦醇溶蛋白/纳米TiO₂可食性膜,并对两种膜的水蒸气透过率(透湿率)、透CO₂率、透O₂率、抗拉伸强度、断裂延伸率进行了对比研究。与大麦醇溶蛋白可食性膜相比,纳米TiO₂粒子的加入使得膜的平均透湿率降低了19.5%,平均透CO₂率、平均透O₂率分别提高了12.8%和17.1%,抗拉强度TS由313.91kPa提高至514.21kPa,断裂伸长率E由487%降低至221%。     

基于螺旋挤压-GVL/水/酸两步预处理的溶解浆联产糠醛和木质素

针对目前溶解浆生产过程中存在的半纤维素和木质素利用率低、溶解浆质量有待提升等问题,本研究基于螺旋挤压耦合γ-戊内酯（GVL）/水/酸预处理,提出绿色环保的溶解浆联产糠醛和木质素的工艺。结果表明,桉木经螺旋挤压-GVL/水/酸两步预处理（150 ℃下反应1.5 h）,蒸煮用碱量8%,漂白工艺OQP₁P₂,制备出α-纤维素含量为96.5%、白度为84.0%的高品质溶解浆;水解液分离木质素后,以甲基异丁基酮（MIBK）/H₂O-NaCl为催化体系,商业离子交换树脂为催化剂,于180 ℃下催化木糖水解液2 h,糠醛最大得率为96.0%;GVL木质素S/G比为4.81,保留一定含量的β-O-4键（22.6%）。经物料衡算,每100 g桉木可生产37.2 g溶解浆、6.2 g糠醛（理论值10.2 g）和16.4 g的GVL木质素。     

全细胞原位催化秸秆稀酸水解液制木糖酸的活性炭脱色

研究旨在探讨活性炭对木质纤维水解液全细胞原位催化制取木糖酸产品的脱色精制技术与工艺条件。在单因素实验基础上,采用正交实验,以脱色率(%)和木糖酸回收率(%)为指标,分别用紫外-可见分光光度法和高效阴离子交换色谱测定研究并确定脱色的最优工艺参数。结果表明:粉状活性炭对秸秆稀酸水解液所制取的木糖酸产品液均具有选择性的吸附功能,对色素杂质的吸附脱除率明显高于对木糖酸的吸附率。C3对木糖酸产品的选择性脱色精制效果最佳。C3活性炭添加量对脱色效果的影响最大,其次为时间和温度,最适脱色工艺条件为:活性炭添加量20%、脱色温度60℃、吸附时间40 min,脱色率达到99.74%,木糖酸回收率可保持90.05%。这说明采用C3粉状活性炭对木糖酸进行脱色和产品精制的技术可行,且快速简便。     

Ag掺杂TiO2光催化剂的制备及其处理造纸废水研究

采用溶胶-凝胶法制备Ag掺杂TiO_2(Ag-TiO_2)光催化剂,采用X射线衍射仪(XRD)、紫外-可见分光光度计(UV-vis)、扫描电子显微镜(SEM)、能谱仪(EDS)对所制备Ag-TiO_2光催化剂进行表征,并用该光催化剂处理中段造纸废水,以降低造纸废水的COD_(Cr)和色度。探讨了Ag掺杂量、造纸废水初始pH值、光催化剂用量和光照时间对处理效果的影响。结果表明,Ag掺杂后TiO_2的结晶度下降,Ag-TiO_2的禁带宽度随Ag掺杂量的增大而减小。废水处理结果表明,当造纸废水初始p H值为6、光催化剂用量为0.6 g/L、Ag掺杂量为3%时,Ag-TiO_2光催化效果最佳,光照12 h后,造纸废水的色度和COD_(Cr)去除率分别达到100%和81.3%。     

Modelling of the hydrolysis of sorghum straw at atmospheric pressure

Sorghum straw is a renewable, cheap and widespread resource. The acid hydrolysis of sorghum straw to obtain xylose solutions could be a good alternative for this abundant resource. The H₂SO₄ hydrolysis of sorghum straw at two different temperatures (80 and 100 °C) and three H₂SO₄ concentrations (2, 4 and 6%) using a solid/liquid ratio of 1:10 (w/w) was studied. Kinetic parameters of mathematical models for predicting the concentrations of xylose, glucose, acetic acid and furfural were determined. The activation energy of the release reaction was 183.3 kJ mol^?1 for xylose and 185.8 kJ mol^?1 for glucose. The optimal conditions found were 6% H₂SO₄ at 100 °C for 60 min, which allow one to obtain a solution with 18.27 g xylose l^?1, 6.78 g glucose l^?1, 0.7 g furfural l^?1 and 1.35 g acetic acid l^?1. It is concluded that this process has potential for utilisation of this renewable lignocellulosic resource. © 2002 Society of Chemical Industry     

Prehydrolysis ofEucalyptus wood with dilute sulphuric acid: operation at atmospheric pressure

MilledEucalyptus globulus wood samples were subjected to acid hydrolysis using H₂SO₄ as catalyst. The reactions were carried out in a stirred, reflux-operated batch reactor. The effects of both catalyst concentration (in the range 3.5–10%) and hydrolysis time (0–11 h) on the concentration of arabinose, glucose, xylose, acetic acid and furfural were studied. The kinetics of xylan hydrolysis followed general trends similar to those described in earlier studies. Almost quantitative xylose recovery was achieved after 11 h of reaction time in experiments with 10% H₂SO₄. The furfural concentrations were low (0–0.44 g/L) in all the cases studied. Additional aspects relative to the selectivity of the prehydrolysis are discussed.     

Production of fermentable media from vine‐trimming wastes and bioconversion into lactic acid by Lactobacillus pentosus

Trimmings of vineshoots, an agricultural waste with little use, were hydrolysed with dilute sulphuric acid (1–5%) in order to obtain sugar solutions suitable as fermentation media. The operational conditions for hydrolysis were selected on the basis of both the generation of hemicellulosic sugars (mainly xylose) and glucose and the concentrations of reaction byproducts affecting fermentation (furfural, hydroxymethylfurfural and acetic acid). Hemicellulosic hydrolysates were supplemented with nutrients and fermented with Lactobacillus pentosus, without any previous detoxification stage, to produce lactic acid. Under the best operational conditions assayed (3% H₂SO₄ and 15 min), 21.8 g lactic acid l^?1 was produced (Q_P = 0.844 g l^?1 h^?1, Y_P/S = 0.77 g g^?1), which represents a theoretical yield of 99.6%. Acetic acid was the primary byproduct formed from xylose, at about 25% of the lactic acid level. Copyright © 2004 Society of Chemical Industry     

Agave sisalana,a biosorbent for the adsorption of Reactive Red 120 from aqueous solution

The textile industry is one of the largest producers of dye effluent. Treatment of these effluents has to be cost effective hence a number of precursors have been studied as a viable alternative adsorbent. Sisal fibre was converted to activated carbon by chemical methods. Sisal fibre was activated with different activating agents such as H₃PO₄, HCl, HNO₃, NaOH and KOH. The adsorption of Reactive Red 120 (RR 120) dye onto sisal fibre activated carbon (SFAC) from aqueous solution was investigated. Adsorption experiments were carried out at different dye concentrations, initial solution pH and carbon dosage. Batch adsorption studies were carried out using activated carbon produced using phosphoric acid yielded better carbon as it good results in terms of Methylene Blue number and Iodine number. These carbons were used to study the batch adsorption studies. Methylene Blue number and Iodine number of SFAC were found to be 240 mg/g and 855 mg/g, respectively. The BET surface area of the carbon was 885 m²/g. The batch experiments adsorption isotherm studies fitted well to Langmuir isotherm and the adsorption capacity was found to be 110 mg/g. Adsorption kinetics data were tested using pseudo-first-order and pseudo-second-order models. Kinetic studies showed that the adsorption data followed a pseudo-second-order reaction.     

黄麻纤维活性炭对亚甲基蓝和甲基橙溶液的吸附性能研究

以黄麻纤维为原料,采用磷酸活化法制得黄麻纤维活性炭作为吸附剂,以纺织印染加工中较为常用的亚甲基蓝(MB)和甲基橙(MO)染料溶液为吸附质,研究染料溶液初始浓度、活性炭投加量、吸附时间等因素对黄麻纤维活性炭吸附性能的影响。结果表明:随着染料溶液初始浓度的增加,两种染料的去除率逐渐降低,吸附量逐渐增大;随着活性炭投加量的增加和吸附时间的延长,两种染料的去除率和吸附量均呈现逐渐增大的变化规律;水浴温度对两种染料的去除率和吸附量影响都较小;染料溶液pH值对两种染料吸附性能的影响存在较大差异,MB的去除率和吸附量随染料溶液pH值增加而增大,而MO的去除率和吸附量随之减小。     

Modified Rice Straw as a Template in Syntheses of Nano TiO2 Loaded on Wool Fibers for Wastewater Treatment

Industrialization of textile produces large amounts of colored wastewater and recycling of that wastewater is recently under the scope. The current work is implemented to use rice straw as a template for preparation of nano TiO₂ to be applied in decolorization of wastewater of textile industries. Different treatments including silica removal and esterification were performed for rice straw to produce highly reactive nanotitanium dioxide. Size, morphological shape, and surface area of the so obtained TiO₂ nanoparticles were observed to be influenced by rice straw treatments. Percentage of anatase phase in titanium dioxide was increased from 41.6% to 75.0% after removing of silica and modification with citric acid of rice straw. The particle size of anatase was significantly reduced from 88.6 nm to 10.5 nm while the BET surface area of nanotitanium dioxide was enlarged from 41.2 m²/g to 84.7 m²/g. The prepared TiO₂ nanoparticles were loaded onto wool fibers and the photocatalytic properties of nano TiO₂ powder before and after loaded to fiber were measured against methylene blue dye. The dye removal percentage raised from 92.5 to 99.2 by using of nano TiO₂ powder-loaded wool fibers compared to nano TiO₂ powder.     

Migration of titanium dioxide from PET/TiO2 composite film for polymer-laminated steel

PET/TiO₂ composite film is the most widely used film for polymer-laminated steel, and the migration of TiO₂ is very important for the safety evaluation of its packaged food. Microwave digestion, wet digestion and dry ashing were used for pretreatment of composite film to determine the content of TiO₂ in composite film. Migration tests were carried out at 40°C, 60°C and 80°C 4% using acetic acid and 50% ethanol as the acid and ester food simulants. The migration amount of TiO₂ was determined by inductively coupled plasma optical emission spectrometry (ICP-OES). With increasing temperature and time, the migration of TiO₂ increased. In 4% acetic acid, the migration amount of TiO₂ at 40°C for 10 days was 1.88 mg kg^?1 and the migration amount at 80°C for 8 h was 3.32 mg kg^?1, indicating that the effect of temperature on migration was more obvious. Under the same conditions, the migration amount of TiO₂ in 4% acetic acid was greater than in 50% ethanol. X-ray diffraction (XRD), scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimeter (DSC) were used to analyse the crystal structure, morphology, chemical groups and thermal properties of the film before and after the migration tests. The results showed that filmTiO₂ had a stable rutile type crystal structure and it was almost uniformly distributed. PET and TiO₂ were combined with strong chemical bonds. After TiO₂ migration, the crystallinity and the glass transition temperature (Tg) of the film decreased, but the change of melting temperature (Tm) was not obvious.     

KOH改性活性炭对木糖液脱色性能的研究

以KOH溶液为改性试剂对磷酸法活性炭(PAC)进行改性,并对木糖液进行脱色。研究表明:以质量分数0.25%KOH溶液对活性炭进行4～6h的处理,可以提高活性炭对木糖液的脱色率,与未改性PAC试样相比,其透光率由44%提高到50%。并且对木糖液中的酚类化合物、氮类物质、铁及糠醛的去除率由46.37%、43.50%、6.40%、11.83%提高到56.87%、53.00%、16.31%、13.17%。活性炭经KOH溶液改性后(KOH-PAC),其表面化学发生了一定的变化,与未改性的PAC试样相比,试样KOH-PAC的碱性官能团数量增加,表面的吸附活性位增多。其吸附能力有一定程度的提高,是一种可行的改性方法。     

造纸废液木素制备粉状活性炭的研究

以碱法木浆废液木素为研究对象,利用磷酸作活化剂对碱木素进行炭化活化,制得粉状活性炭,优化工艺条件,得出最佳的工艺条件为:磷料比4.5∶1,活化温度500℃,活化时间10min。在此条件下制得活性炭产品的亚甲基蓝吸附值达8.6mL/0.lg活性炭得率为31.25%。进一步对所得产品的表面结构、元素组成、比表面积及孔径分布进行表征。