玉米秸秆活性炭的制备及其对养殖废水中土霉素的去除

采用热解法,以磷酸为活化剂,以玉米秸秆为碳源,制备了玉米秸秆活性炭,利用扫描电镜表征了其表面形貌,采用平衡吸附法研究了玉米秸秆活性炭对溶液中土霉素的吸附性能和对养殖废水中土霉素的去除效果。结果表明:在室温下,玉米秸秆活性炭对土霉素的最大吸附量为192.5 mg/g;吸附平衡时间为30 min;当pH值在4.3～8.2范围内,pH值对玉米秸秆活性炭去除土霉素没有显著性影响;利用玉米秸秆活性炭去除养殖废水土霉素的去除率达到93.1%。     

玉米秸秆活性炭的制备及其对四环素的吸附

采用热解法,以磷酸为活化剂、玉米秸秆为碳源,制备了玉米秸秆活性炭。利用扫描电镜表征了其表面形貌,采用平衡吸附法研究了玉米秸秆活性炭对溶液中四环素的吸附性能和对养殖废水中四环素的去除能力。结果表明,在20℃,pH 7,吸附平衡时间为45 min时,玉米秸秆活性炭对四环素的最大吸附量为212.6 mg/g;利用玉米秸秆活性炭去除含有四环素的养殖废水时,四环素的去除率为94.8%。     

磷酸改性向日葵秸秆对Cr~(6+)的吸附性能

以向日葵秸秆为原料,用磷酸改性制备秸秆活性炭,研究了秸秆活性炭的投加量、pH值、吸附时间和温度等因素对水溶液中Cr6+吸附的影响。结果表明:向日葵秸秆活性炭对Cr6+有很强的吸附去除作用;在吸附震荡时间为1.5 h,温度为25℃,吸附剂的投加质量浓度为8 g/L,pH值为4—7时,向日葵秸秆活性炭对Cr6+的吸附去除率为98.9%以上;升高温度有利于吸附,Langmuir等温模型能很好地反映吸附过程特征,吸附过程符合准二级动力学方程。     

秸秆-污泥基活性炭的制备及其对吸附Pb2+的研究

基于实验室制备秸秆-污泥基活性炭和中小城镇生活垃圾双解技术的研究,开发了一套制备水稻秸秆-污泥基活性炭的成套装置,并在最佳条件下制备得到了秸秆-污泥基活性炭。实验结果表明,秸秆-污泥基活性炭主要官能团有—OH、—C=C—、C—O,比表面积为902.6 m2/g,总孔容为0.303 0 cm3/g,微孔容为0.205 0 cm3/g。考察了活性炭对Pb2+的吸附效果的影响,结果表明,在吸附时间为200 min、pH为6、活性炭投加量为6 g/L的条件下对Pb2+的吸附量为12.79 mg/g,吸附过程符合二级吸附动力学模型。     

向日葵秸秆活性炭对Cr~(6+)吸附研究

以向日葵秸秆为原料用浓磷酸改性后制成向日葵秸秆活性炭,研究了pH对向日葵秸秆活性炭对Cr(Ⅵ)溶液吸附效果,并讨论了吸附过程的动力学特征。结果表明:Cr(Ⅵ)溶液pH为2.0,去除效果最佳;升高温度有利于吸附,秸秆活性炭对Cr(Ⅵ)的吸附过程更符合Dubinin-Radushkevick吸附方程,且受温度影响很大。     

水稻秸秆制备活性炭吸附剂工艺研究

以水稻秸秆为原料、氢氧化钠为活化剂制备活性炭。结果表明水稻秸杆活性炭的最佳工艺条件:碱碳比为2∶1,活化时间为60 min,活化温度为600℃,碳化温度为350℃,在此工艺条件下制备的水稻秸秆活性炭的亚甲基蓝吸附值和碘吸附值分别为29.2 mL/0.1 g和1 706.98 mg/g,制备出的活性炭吸附剂质量指标接近水质净化用活性炭标准。     

农业秸秆制备活性炭的最佳工艺及吸附性能研究

随着社会经济与工业的不断发展,人们的生活水平显著提高,但随之而来的环境问题也日益突出,尤其是大量污染物进入到水体,导致水资源严重污染。为保障水资源质量与安全,要求采取预处理措施进行废水处理。活性炭吸附法在废水处理领域应用较为广泛。考虑到我国农作物秸秆资源丰富的实际,通过农业秸秆制备活性炭既可以解决秸秆焚烧问题,还能够提高资源利用率。重点对农业秸秆制备活性炭的最佳工艺及吸附性能进行研究。     

磷酸法玉米秸秆基活性炭的制备及其表征

以成型、烘焙处理后的玉米秸秆为原料,磷酸作为活化剂制备了玉米秸秆基活性炭,并对活性炭样品进行表征。同时以碘吸附值、亚甲基蓝吸附值和焦糖脱色率为指标测定其吸附性能,并对制备条件进行优化。实验结果表明:玉米秸秆制备活性炭的最佳工艺条件为浸渍比即m(55%H₃PO₄)∶m(玉米秸秆)为4∶1、活化温度400℃、活化时间100 min,此条件下活性炭的得率为47.78%,制得的活性炭具有良好的吸附性能,碘吸附值、亚甲基蓝吸附值及焦糖脱色率分别达到864 mg/g、 210 mg/g和100%。活性炭比表面积可达1 105 m²/g,总孔容积为0.745 cm³/g,微孔孔容为0.287 cm³/g,中孔孔容为0.354 cm³/g,孔径分布集中于5 nm以内,约占73.56%,平均孔径为2.697 nm。FT-IR分析显示:在活化过程中磷酸与玉米秸秆发生交联作用,生成的活性炭损失了玉米秸秆的部分官能团。     

烘焙预处理对玉米秸秆磷酸法活性炭制备及性能影响

以玉米秸秆为原料,研究烘焙预处理对磷酸法活性炭的制备及性能影响。研究结果表明：烘焙预处理使玉米秸秆碳元素含量和固定碳含量增加而挥发分含量降低,增加热解焦炭质量,且烘焙温度影响强于烘焙时间。烘焙处理使玉米秸秆活性炭比表面积先增加后减小,总孔容和中孔率减小,而微孔率显著增加。烘焙预处理有助于提高活性炭吸附性能,当100 g粒径为154～450μm玉米秸秆颗粒经烘焙预处理,预处理条件为烘焙温度240℃、烘焙时间60 min时,预处理后的玉米秸秆含C 51.32%,固定碳27.64%,灰分4.72%。采用磷酸活化法将预处理后的玉米秸秆制备成活性炭,制备条件为浸渍比1∶4(玉米秸秆与55%磷酸溶液的质量比),浸渍温度140℃,浸渍时间90 min,活化温度400℃,活化时间60 min,此条件下制备的玉米秸秆活性炭比表面积达1 317.05 m²/g,碘吸附值、亚甲基蓝吸附值和焦糖脱色率分别为876 mg/g、 210 mg/g和100%。     

玉米秸秆活性炭的制备及其吸附含氮废水性能探析

采用玉米秸秆作为制备原料,KHCO₃为活化剂、HCl作为改性试剂制备改性玉米秸秆活性炭,吸附含氮废水,进行物理表征以及吸附动力学性能分析。本实验采取Freundlich与Langmuir模型对等温吸附曲线进行线性拟合,实验数据结果表明,玉米秸秆活性炭对氮素的吸附更加符合Freunglich方程,拟合相关性较好,R²=0.998。随后采用Lagergren准一级及准二级动力学速率模型对活性炭吸附氮素溶液动力学拟合,实验结果表明,Lagergren准二级速率模型可以最准确地描述吸附过程,其中R²=0.95。玉米秸秆活性炭对氨氮的最大吸附量常数达到407.51 mg·g^-1,表明吸附能力较强。     

非均相催化臭氧氧化深度处理造纸废水的性能

采用农业废弃物水稻秸秆制备秸秆基活性炭,将其负载过渡金属Mn和Fe作为臭氧催化剂。采用正交试验考察了制备参数对其催化活性的影响,结果表明,最佳制备条件:浸渍时间为12 h,热解温度为500℃,热解时间为3 h。以制备的催化剂催化臭氧氧化深度处理造纸废水,COD和色度平均去除率分别为74.3%和80.5%,处理出水达到《城镇污水处理厂污染物排放标准》(GB 18918—2002)的一级A排放标准。制备的催化剂稳定性高且经济环保,适于造纸废水深度处理的工程应用。     

Preparation and characteristics of rice-straw-based porous carbons with high adsorption capacity

To prepare porous carbons with high adsorption capacity from rice straws, two different kinds of precursors, i.e. one as the raw rice straws (one-stage process) and the other as pre-carbonized rice straws (two-stage process), were activated with KOH of various impregnation ratios. The two-stage process was found very effective for manufacturing porous carbons with high surface area and adsorption capacities for MB and I₂. For example, the porous carbon that was carbonized at 700°C and subsequently activated at 900°C exhibited the surface area of 2410 m²/g, the adsorption capacities of 800 and 1720 mg/g for MB and I₂, respectively, and the total pore volume of 1.4 ml/g. In the two-stage method, there was a preferential optimum impregnation ratio of KOH to a precursor carbon, i.e. 4:1, with which high surface area of porous carbons could be achieved. The formation of uni- and bidentate carboxylic salt structure, induced by reaction between KOH and oxygen containing carbon, that facilitates the formation of azo group (-NN-) on a subsequent heat treatment was considered as one of the key factors for the presence of optimum impregnation ratio of KOH. In contrast, the porous carbons of only moderate adsorption capacity could be obtained from the one-stage method. The original morphology of rice straw was sustained during the two-stage process, yet not during the one-stage process.     

磷酸法水稻秆活性炭的制备

以水稻秆为原料,采用磷酸活化法制备活性炭。研究了浸渍比、活化温度对活性炭样品吸附性能的影响,并对其微结构进行N₂吸附等温线、热重-微商热重法(TG-DTG)、扫描电子显微镜(SEM)等表征。结果表明:水稻秆适合作为磷酸法活性炭的原料,吸附性能达到市售脱色活性炭的指标要求。在浸渍比为3∶1、活化温度 450 ℃、活化时间 60 min 的条件下,制得活性炭的亚甲基蓝吸附值 215 mg/g,碘吸附值 855 mg/g,A法焦糖脱色率 110 %,BET比表面积 967.72 m²/g,总孔容积 1.23 cm³/g,中孔率 84.6 %,平均孔径 4.6 nm。     

Mesoporous Carbon Fibers Prepared from Regenerated Rice Straw Fibers

Regenerated cellulose fibers from rice straws with a diameter of 10 to 25 μm and initial modulus of 11 to 13 GPa were prepared by wet spinning in rice straw/N‐methylmorpholine‐N‐oxide (MMO) solution. X‐ray diffraction analysis indicates that the rice straw regenerated fibers are classified as cellulose (II). From the regenerated cellulose fiber based on rice straw, mesoporous carbon fiber was prepared by carbonization. This observation indicates that a potential utility of rice straw as a new mesoporous materials.     

Impregnation of Hardboard with Poly(methyl methacrylate)

The increasing deficiency of natural woods has led to the use of agricultural residues in the preparation of pulp and boards. The important agricultural residues are bagasse, straws, and cotton stalks, which accumulate in vast amounts. Some studies concerning the use of bagasse (Lumen et al., 1963), rice straw (Mobarak et al., 1975; Fadl et al., 1984), cotton stalks (Mobarak and Nada, 1975), and other agricultural residues (Lathrop and Naffziger, 1949; Aronosky and Lathrop, 1949) for producing hardboards are available. Actually, resins are added to pulp before board formation to give a final board of high strength and water resistance. The common resins are phenol-formaldehyde, urea-formaldehyde, and melamine- formaldehyde. Also, in one of our previous works, whole black liquor (Nada et al., 1982), produced from rice straw pulping process or its separated components (lignin, hemicellulose, and silica) (El-Saied et al., 1982) in the presence or absence of phenol-formaldehyde resin during hardboard preparation, was used to improve the strength properties of board. Other treatments are used to modify the hardboard or paper sheet properties, by impregnation of the sheets in resin solution (Plomely and Cottstein, 1968; Nada et al., 1981) or by polymer solution (Calleton et al., 1970; Youssef et al., in press). In addition, chemical modifica-tions such as acetylation, grafting (Smraishi et al., 1982). and cyanoethylation are carried out on wood and hardboard to improve their dimensional stability.     

Fibreboard from exotic raw materials. Ii. Hardboard from undebarked cotton stalks

It was possible to obtain hardboard of acceptable properties by mechanical pulping of undebarked cotton stalks previously soaked in water at room temperature. Pretreatment of the undebarked cotton stalks with 10–15% NaOH or Ca(OH)₂ at atmospheric pressure for 4 h at 100°C, before mechanical defibration, results in considerable improvement in properties of the hardboard and less added resin requirement. The improvement due to chemical pretreatment is attributed to fibre softening. The semichemical pulps prepared from undebarked cotton stalks had remarkably high freeness compared with rice straw. Bending strength and water resistance are better than those obtained from rice straw and average samples of wood wastes.     

碳源对平菇选择性降解稻草木素及其后续酶解性能的影响

前期研究发现,平菇预处理稻草表现出比较好的脱木素选择性和纤维素酶水解效果。为了使预处理后的稻草在纤维素酶水解过程中得到更多的单糖,通过向平菇预处理稻草固体培养基中添加麸皮、玉米皮和木聚糖,研究外加碳源对平菇降解稻草木素的选择性及后续酶水解效果的影响。结果表明,添加适量的麸皮和木聚糖可提高平菇处理稻草的脱木素选择性。麸皮和木聚糖添加量为稻草粉的10%时,脱木素选择系数分别由对照的1.86增加至2.58和2.03;预处理样品酶解后原料中总糖的46.8%和45.9%转化为可发酵单糖,分别比对照的35.5%提高了30%和28%。添加玉米皮对平菇预处理酶解效果影响相对较小,添加量为5%时,预处理样品酶解后总糖转化率仅比对照提高15%,增加添加量酶解总糖转化率反而低于对照样品。     

活性炭纤维对钯的吸附性能研究

活性炭纤维是一种新型高效吸附材料,具有比表面积大,微孔发达,孔径分布窄,吸附速度快,吸附能力强等特点.通过活性炭纤维对钯溶液的吸附实验,探讨了静态条件以及动态条件下,溶液的初始浓度,系统的温度,活性炭纤维的质量,吸附时间,不同流速等条件对活性炭纤维吸附性能的影响.研究表明:活性炭纤维对钯有较强的吸附性能,最高吸附率可达...     

乙酰化稻草秸秆的制备及表征

通过稻草秸秆与乙酸酐的反应,制备了一种廉价的可降解的乙酰化稻草纤维热塑性材料。利用傅里叶红外光谱(FT-IR),X射线衍射(XRD)、示差扫描量热(DSC)和热重分析(TGA)等分析手段对产物的结构、结晶性能、热学性能等进行了表征。结果显示,当乙酸酐、乙酸的用量分别为秸秆质量的2倍和10倍时,在9%H2SO4催化下,于50℃反应2 h,获得的改性稻草秸秆纤维具有良好的热塑性能。     

煤粉大比例掺混不同生物质的混燃特性研究

可再生能源生物质清洁低碳、易于获取、利于着火,含硫、氮量少且属于碳中性物质,但其能量密度低。在煤粉中大比例掺混生物质(生物质/煤粉质量比大于5∶5)可有效改善煤粉着火特性,碳排放水平接近燃烧天然气,且污染物排放显著降低,进而达到节能减排目的。目前研究主要集中在低掺混比例(小于5∶5)下生物质与煤粉的混燃特性,针对北方常见的玉米秸秆、稻杆和玉米芯等生物质与煤粉在大掺混比例下的燃烧特性,尚有待深入。笔者利用热重分析技术分别研究了煤粉与不同生物质种类(玉米秸秆、稻杆及玉米芯)在不同掺混比例下(5∶5、6∶4、7∶3和8∶2)的混燃特性,分析生物质种类和掺混比例对混合燃料的着火温度、燃尽温度、交互反应以及燃烧特性指数等的影响,确定了不同生物质的最佳掺混比例。结果表明:掺混比例对混合样品失重曲线的影响从大到小依次为玉米秸秆、玉米芯和稻杆。随掺混比例增加,第1阶段最大质量变化速率逐渐增大且燃烧进程前移,第2阶段则逐渐减小,这是由于挥发分相对增加且焦炭相对减少的原因。混合样品的着火温度和燃尽温度比纯煤粉分别下降约100和60℃。随掺混比例的增加,玉米芯着火温度逐渐减小,玉米秸秆和稻杆则先减小后增大,且均在7∶3时达到最小;燃尽温度均呈现下降趋势,下降幅度由大到小分别为玉米芯、稻杆和玉米秸秆。玉米秸秆和稻杆在8∶2时燃尽性能较差。混合样品发生不同程度的交互作用,该交互作用正是生物质的促进和抑制的协同作用,使3种生物质均在5∶5时对煤粉燃烧抑制作用大;玉米秸秆和稻杆在7∶3时、玉米芯在6∶4、8∶2时促进作用大。同时,3种生物质的燃烧特性指数远大于煤粉,随掺混比例的增大,玉米芯的燃烧特性指数变化最大并在8∶2时达到最大值,6∶4和7∶3时几乎相同;稻杆的变化最小且在7∶3时达到最大值;玉米秸秆在7∶3和8∶2时几乎相同并达到最大值。小范围改变掺混比例时,燃烧特性指数变化不大。这可能是由于燃烧特性指数不仅与着火温度和燃尽温度有关,还与样品在其主要燃烧过程的反应速率有关,而煤粉在焦炭燃烧阶段的反应剧烈程度高于生物质挥发分析出阶段,使不同掺混比例的混合样品出现以上现象。