Thermal pretreatment of willow branches impacts yield and pore development of activated carbon in subsequent activation with ZnCl_(2) via modifying cellulose structure

Development of pore structures of activated carbon(AC)from activation of biomass with ZnCl_(2) relies on content and structure of cellulose/hemicellulose in the feedstock.Thermal pretreatment of biomass could induce dehydration and/or aromatization to change the structure of cellulose/hemicellulose.This might interfere with evolution of structures of AC,which was investigated herein via thermal pretreatment of willow branch(WB)from 200 to 360℃and the subsequent activation with ZnCl_(2) at 550℃.The results showed that thermal pretreatment at 360℃(WB-360)could lead to substantial pyrolysis to form biochar,with a yield of 31.9%,accompanying with nearly complete destruction of cellulose crystals and remarkably enhanced aromatic degree.However,cellulose residual in WB-360 could still be activated to form AC-360 with specific surface area of 1837.9 m~2·g^(-1),which was lower than that in AC from activation of untreated WB(AC-blank,2077.8 m~2·g^(-1)).Nonetheless,the AC-200 from activation of WB-200 had more developed pores(2113.9 m~2·g^(-1))and superior capability for adsorption of phenol,due to increased permeability of ZnCl_(2) to the largely intact cellulose structure in WB-200.The thermal pretreatment did increase diameters of micropores of AC but reduced the overall yield of AC(26.8%for AC-blank versus 18.0%for AC-360),resulting from accelerated cracking but reduced intensity of condensation.In-situ infrared characterization of the activation showed that ZnCl_(2) mainly catalyzed dehydration,dehydrogenation,condensation,and aromatization but not cracking,suppressing the formation of derivatives of cellulose and lignin in bio-oil.The thermal pretreatment formed phenolic-OH and C=O with higher chemical innerness,which changed the reaction network in activation,shifting morphology of fibrous structures in AC-blank to“melting surface”in AC-200 or AC-280.

Effects of Ultrasound/Dilute H_2 SO_4 Pretreatment on Cellulase Activity of Corn Straw Liquid Fermentation

[ Objective] The aim was to study pretreatment of ultrasound enhancing dilute H2SO4 on cellulase activity of corn straw liquid fermentation and explore the pretretment＇ s optimal conditions. [ Method ] By using orthogonal test, the pretretment of ultrasound enhancing dilute H2SO4 on corn straw was studied, then straw was fermented as the sole carbon source. Finally, the cellulase activity in extracellular fermentation broth was determined. [Result] The results showed that cellulase activity in extracellular broth was greatest under the conditions of acid bath time 3 h, acid concentration 3.5%, ultrasonic power 150 W, and ultrasonic time 5 h. They were FPA 15.82 U/ml, Cx 39.9 U/ml, 13-Giu 55.94 U/ml respectively. [ Conclusion] Under the above conditions, extracellular cellulase production has a high stability.

Dechromization and dealumination kinetics in process of Na_2CO_3-roasting pretreatment of laterite ores

A novel process was proposed for the activation pretreatment of limonitic laterite ores by Na2CO3 roasting. Dechromization and dealumination kinetics of the laterite ores and the effect of particle size, Na2CO3-ore mass ratio, and roasting temperature on Cr and Al extraction were studied. Experimental results indicate that the extraction rates of Cr and Al are up to 99%and 82%, respectively, under the optimal particle size of 44–74μm, Na2CO3-to-ore mass ratio of 0.6：1, and temperature of 1000 ℃. Dechromization within the range of 600–800 oC is controlled by the diffusion through the product layer with an apparent activation energy of 3.9 kJ/mol, and that it is controlled by the chemical reaction at the surface within the range of 900–1100 ℃ with an apparent activation energy of 54.3 kJ/mol. Besides, the Avrami diffusion controlled model with on apparent activation energy of 16.4 kJ/mol is most applicable for dealumination. Furthermore, 96.8%Ni and 95.6%Co could be extracted from the alkali-roasting residues in the subsequent pressure acid leaching process.

功能化氮杂环卡宾聚合树脂对Cu^(2+)的吸附研究

该研究制备了功能化氮杂环卡宾聚合树脂(PNO),旨在去除废水中Cu^(2+);基于静态和动态吸附实验,研究了PNO对废水中Cu^(2+)的吸附效果。结果表明:PNO对Cu^(2+)的最佳吸附条件为吸附剂投加量100 mg、吸附时间30 min、pH值4.0~5.9、温度298 K、转速150 r/min,最大吸附量为51.55 mg/g。PNO对Cu^(2+)的吸附过程符合Langmuir、Freundlich等温吸附模型和准二级动力学模型。动态吸附量随柱高增加、流速降低和进水Cu^(2+)浓度增加而增大。使用Thomas和Bohart-Adams模型拟合,相关系数R^(2)均大于0.92,预测值与实验值相符。经过5次静态吸附-解吸和3次动态循环再生后,PNO对Cu^(2+)的去除率仍达到第一次循环的96%以上,去除效果和再生性能良好。PNO对含铜废水高效处理具有广泛的应用前景。

磁性三乙烯四胺/单宁树脂对Cu^(2+)、Pb^(2+)的吸附性能研究

利用曼尼希反应将三乙烯四胺(TETA)固化到单宁(TA)基体表面,热溶剂法制得磁性单宁基树脂(MTETA-TA)。通过红外光谱、扫描电镜、比表面积及孔隙度分析仪、振动样品磁强计对M-TETA-TA进行表征,表明M-TETA-TA具有疏水性强、比表面积大的优势,Fe_(3)O_(4)的成功引入有效解决吸附剂回收难的问题。对含Cu^(^(2+))、Pb^(2+)废水溶液进行了静态吸附实验,探讨了其对金属的吸附性能。在pH为5的酸性条件下,吸附效果较好;Cu^(^(2+))和Pb^(2+)吸附动力学均符合准二级反应动力学模型,主要为化学吸附;Cu^(^(2+))的吸附等温线符合Langmuir模型,属单层吸附,理论吸附最大值为173.33 mg·g^(-1);Pb^(2+)的吸附等温线符合Sips模型,属多层吸附,理论吸附最大值为217.14 mg·g^(-1)。推测M-TETA-TA对Pb^(2+)的吸附除了螯合、氧化还原等化学反应,还存在静电和离子交换作用,氨基和酚羟基为主要参与官能团。循环再生5次后,仍有较高的吸附性能和磁性强度。

ZIF-8/PEO杂化泡沫对TC和Cu^(2+)吸附研究

以提高金属有机骨架ZIF-8水处理中可回收性为目标,利用聚氧化乙烯PEO作为致孔剂,采用冰模板-冷冻干燥法制备金属有机骨架杂化泡沫ZIF-8/PEO,利用XRD、SEM、TG-DSC和N2吸附-脱附等表征手段,分析ZIF-8/PEO杂化泡沫的理化性能,研究ZIF-8/PEO对四环素TC和铜离子Cu^(2+)吸附性能及吸附机理。试验结果表明:ZIF-8/PEO形成了更加规则的网状结构且具有良好的机械强度和吸附性能。在吸附时间12 h,pH 7,吸附剂投加量40 mg,TC和Cu^(2+)初始浓度均为30 mg/L的最佳条件下,ZIF-8/PEO对TC和Cu^(2+)的吸附容量为107.55 mg/g和107.81 mg/g;等温吸附过程符合Langmuir模型,动力学过程符合拟二级动力学模型,ZIF-8/PEO吸附TC,Cu^(2+)属于自发、放热、趋于有序的过程。在循环吸附7次后,ZIF-8/PEO吸附剂对TC和Cu^(2+)的去除率仍在70%以上。

Influence of pretreatment process on structure, morphology and electrochemical properties of Li[Ni_(1/3)Co_(1/3)Mn_(1/3)]O_2 cathode material

The layered Li[Ni1/3Mn1/3Co1/3]O2 was separately synthesized by pretreatment process of ball mill method and solution phase route, using [Ni1/3Co1/3Mn1/3]3O4 and lithium hydroxide as raw materials. The physical and electrochemical behaviors of Li[Ni1/3Mn1/3Co1/3]O2 were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, field emission scanning electron microscopy （FESEM） and electrochemical charge/discharge cycling tests. The results show that the difference in pretreatment process results in the difference in compound Li[Ni1/3Co1/3Mn1/3]O2 structure, morphology and the electrochemical characteristics. The Li[Ni1/3Mn1/3Co1/3]O2 prepared by solution phase route maintains the uniform spherical morphology of the [Ni1/3Co1/3Mn1/3]3O4, and it exhibits a higher capacity retention and better rate capability than that prepared by ball mill method. The initial discharge capacity of this sample reaches 178 mA-h/g and the capacity retention after 50 cycles is 98.7% at a current density of 20 mA/g. Moreover, it delivers high discharge capacity of 135 mA-h/g at a current density of 1 000 mA/g.

不同质量浓度Cu^(2+)和Ag^(+)对大麦成熟胚组培特性的影响

【目的】探究不同质量浓度Cu^(2+)和Ag^(+)对大麦成熟胚组培特性的影响。【方法】以Bowman、北青7号和光头大麦的成熟胚为材料,研究不同质量浓度Cu^(2+)和Ag^(+)对大麦成熟胚愈伤诱导率、长根率、长芽率、褐化率、绿化率、再分化率和愈伤湿质量的影响。【结果】Bowman、北青7号和光头大麦成熟胚的7种组培特性间存在不同程度差异。与对照相比,0.75 mg/L Cu^(2+)可减少10.43%的成熟胚长根、7.48%的成熟胚长芽、8.24%的愈伤组织褐化、20.74 mg的愈伤湿质量;4.00 mg/L Ag^(+)可提高6.47%的愈伤组织诱导率,可减少9.08%的成熟胚长根、7.96%的成熟胚长芽和9.67%的愈伤褐化;0.75 mg/L Cu^(2+)和4.00 mg/L Ag^(+)对愈伤细胞转绿、愈伤增殖和再分化均无抑制。【结论】适宜质量浓度的Cu^(2+)和Ag^(+)可有效抑制大麦成熟胚长根、长芽和愈伤组织褐化,Ag+还可有效提高愈伤诱导率;在基于MS培养基的大麦成熟胚愈伤组织诱导和再分化培养中,Cu^(2+)和Ag^(+)的适宜质量浓度分别为0.75和4.00 mg/L。研究结果可为构建大麦成熟胚的愈伤诱导及其再分化技术体系提供理论支持。

钠化污泥生物炭复合凹凸棒石对水体中Cu^(2+)的吸附效果研究

含铜废水严重威胁人体健康和环境安全,利用废弃污泥和凹凸棒石制备了钠化污泥生物炭复合凹凸棒石材料,并将其用于含Cu^(2+)废水的处理。利用SEM、XRD及FT-IR对材料的结构和表面性质进行了分析表征,复合材料表面的含氧官能团的络合或C=C键的Π电子作用是吸附重金属的主要机制。研究了复合材料对Cu^(2+)的吸附效果和机理,结果表明,污泥/凹凸棒石质量比2∶1,pH=5,添加量为1.5 g/L,Cu^(2+)初始浓度4 mg/L条件下,材料对Cu^(2+)有最大的吸附容量为3.339 mg/g。吸附过程更好地拟合了准二级动力学模型和Langmuir吸附等温式,表明材料对Cu^(2+)的吸附是单分子层化学吸附。利用响应面分析法预测,pH值为5.04,吸附剂添加量1.16 g/L,Cu^(2+)初始浓度3.60 mg/L是最佳吸附条件。钠化污泥生物炭复合凹凸棒石在实际含铜废水处理中是一种极具潜力的吸附剂。

两种磁性生物炭耦合Diaphorobacter sp.DFA4去除2,4-DFA和Cu^(2+)的特性

以橘子皮为原料,氯化铁、镍锰铁氧体为磁性介质,制备了氯化铁和镍锰铁氧体改性生物炭(分别记为FBC和MBC),重点考察FBC和MBC介导Diaphorobacter sp.DFA4耦合体系去除2,4-二氟苯胺(2,4-DFA)和Cu^(2+)的特性。结果表明:在0.5~2.0 g/L FBC/MBC的介导作用下,Diaphorobacter sp.DFA4对2,4-DFA和Cu^(2+)的去除效果明显提升。当2,4-DFA初始质量浓度为100~900 mg/L时,相比纯菌Diaphorobacter sp.DFA4培养体系,FBC和MBC介导耦合体系对2,4-DFA的降解强化倍数分别为2.24~4.04倍和1.96~4.71倍,Cu^(2+)去除率则分别由59.70%~69.95%提升至88.57%~93.20%和82.12%~88.20%。当pH为6.0~8.0时,较纯菌Diaphorobacter sp.DFA4培养体系,MBC、FBC介导耦合体系对2,4-DFA的去除率分别提高了15.35%~36.32%和22.43%~37.42%,对Cu^(2+)的去除率则分别提高了37.63%~42.34%和43.61%~47.83%;当盐度由0提高至4%时,两个耦合体系对2,4-DFA的去除率基本保持在85%及以上,而纯菌Diaphorobacter sp.DFA4培养体系对2,4-DFA的去除率则由77.98%降至55.19%。机理分析发现,耦合体系可诱导分泌更多的腐殖酸,且在偏碱条件下,FBC更有利于促使腐殖酸的分泌。

Fe^(2+)、Cu^(2+)诱导工艺对柞木表板颜色变化规律的影响

木材中的木质素、抽提物等物质具有能与金属盐溶液产生颜色反应的特性。利用这一特性以硫酸亚铁、硫酸铜溶液作为诱导剂,通过正交试验得到色差最大时的工艺参数,探究金属Fe^(2+)、Cu^(2+)的诱导剂质量分数、诱导时间、干燥时间、干燥温度对实木复合地板柞木表板颜色变化的影响。结果表明:Fe^(2+)、Cu^(2+)的诱导剂质量分数对柞木表板色彩色调的影响极为显著(F值分别为20.4453、8.8442);柞木表板的明度色品指数(L^(*))、红绿轴色品指数(a^(*))、黄蓝轴色品指数(b^(*))均随着Fe^(2+)、Cu^(2+)的诱导剂质量分数、诱导时间、干燥时间的增加而逐渐减少,总色差(ΔE^(*))逐渐增大,最大为31.53、9.90,表板色调逐渐偏暗、偏绿、偏蓝;随着干燥温度的增加,Fe^(2+)、Cu^(2+)诱导时的柞木表板总色差都逐渐减小。

Cu^(2+)对水体中氧氟沙星光化学降解的影响

水体中氟喹诺酮类抗生素(Fluoroquinolone,FQs)易与金属离子发生络合反应,从而影响其潜在的环境行为及生态效应。本文以典型氟喹诺酮类抗生素氧氟沙星(OFX)为例,系统探讨了二价铜离子(Cu^(2+))对其光化学转化降解特性的影响。综合荧光、紫外光谱分析,发现Cu^(2+)与OFX在pH中性条件下能够形成络合比为1∶1的络合物。在365 nm单波长光源的照射下,Cu^(2+)的加入抑制了OFX光降解,荧光猝灭及激光闪光光解实验表明,该抑制作用主要是由Cu^(2+)对OFX光致激发的静态猝灭作用导致。质谱分析结果表明,OFX直接光降解路径包括脱羧、光氧化、哌嗪环氧化裂解和去甲基化等,Cu^(2+)存在条件下去甲基化产物未被检出。毒性分析结果表明,Cu^(2+)的存在降低了OFX转化过程对水生生物的生态毒性。

土-膨润土混合物对Cu^(2+)吸附特征试验研究

为深入分析土-膨润土混合物对重金属离子的吸附特性,文章开展典型尾矿库中Cu^(2+)在土-膨润土混合物中的吸附试验,探讨土-膨润土混合物对Cu^(2+)的吸附特征。结果表明:增大膨润土掺量,土-膨润土混合物对Cu^(2+)最大吸附量和去除率均提升;同一膨润土掺量下,初始Cu^(2+)质量浓度越高,去除率越低。吸附等温模型分析表明:3种模型均适用于试验的吸附特征,基于Langmuir模型的最大吸附量在膨润土掺量增加至20%时,Cu^(2+)最大吸附量Q_(m)增加了29.99%,表明膨润土的掺入可显著提升混合物吸附能力;基于Freundlich模型的吸附常数K_(F)随膨润土掺量增大而增大,表明膨润土掺量越大,吸附能力越强;基于D-R模型,当膨润土掺量为0~20%时,混合物吸附特性主要由离子交换吸附所控制,并通过X射线衍射(X-ray diffraction,XRD)、扫描电子显微镜(scanning electron microscope,SEM)等分析,表明土-膨润土的吸附机理主要表现为离子交换吸附。

UiO-66-NH_(2)的改性及其吸附Cu^(2+)性能

通过溶剂热法合成了锆基金属有机框架材料中的UiO-66-NH_(2),用多巴胺(DA)对其进行后合成改性,制备了UiO-66-NH_(2)/PDA复合材料,用于去除重金属Cu^(2+)。探究了pH、初始ρ(Cu^(2+))、接触时间和温度对吸附过程的影响,结果表明,Cu^(2+)的吸附动力学和等温线数据分别符合准二级和Langmuir模型,吸附过程为自发吸热反应;初始ρ(Cu^(2+))=50 mg/L,pH=5.5,t<30 min,Cu^(2+)去除率为93%。

用于吸附养殖尾水中Cu^(2+)的温度敏感型淀粉基水凝胶制备及性能分析

为了快速移除水产养殖尾水中的铜离子(Cu^(2+)),合成了一种新型温度敏感多糖基水凝胶,以具有结构和性能优势的2-羟基-3-异丙氧基丙基淀粉醚(HIPS)和羧甲基淀粉钠(CMS)为原料,以乙二醇二缩水甘油醚(EDGE)和CaCl 2为交联剂,通过形成共价键和离子键的混合交联方式制备具有温度敏感性能的HIPS/CMS复合凝胶,利用傅里叶转换红外光谱(FT-IR)、扫描电镜(SEM)对复合凝胶的结构和内部形貌进行表征,研究复合凝胶的温度敏感性能,并探究了复合凝胶对水产养殖尾水中Cu^(2+)的吸附效果。结果表明:HIPS/CMS复合凝胶具有优异的温度敏感性能,当温度高于其体积相转变温度(VPTT,34.1℃)时,复合凝胶体积明显收缩,溶胀率从62.1倍下降至33.6倍;HIPS/CMS复合凝胶对水产养殖尾水中Cu^(2+)具有良好的吸附性能,最大吸附量可达25.2 mg/g;复合凝胶对Cu^(2+)吸附过程符合Langmuir吸附模型,属于单分子层化学吸附;利用该复合凝胶的温度敏感性能,可实现HIPS/CMS复合凝胶的回收再利用,并且经5次吸附-解吸循环后吸附量仍可达15.1 mg/g。研究表明,本研究制备的HIPS/CMS复合凝胶对养殖尾水中的Cu^(2+)的去除效果较好且绿色环保,可以重复使用。

Cu^(2+)污染原状黄土的物化及结构特性

为制定环境保护和土壤污染防治和修复策略,以及为污染场地工程建设提供理论支撑,该文研究了Cu^(2+)对原状黄土物化特性及结构特性的影响。通过制备不同掺量的Cu^(2+)污染黄土试样,进行了粒径分布、CaCO_(3)含量和pH值的测定。利用扫描电镜和激光粒度仪获得试样的SEM图像和粉粒各粒径含量,并借助分形理论深入分析了Cu^(2+)对原状黄土微观结构的影响机理。对Cu^(2+)污染的原状黄土试样进行了压缩试验,并对试样的综合结构势进行了分析。结果表明,随着Cu^(2+)掺量的增大,黏粒含量表现为先增后减,再增再减的趋势,粉粒含量则表现为先减后增,再减再增,砂粒含量保持不变;CaCO_(3)的含量呈线性减小;pH值先迅速减小,后保持不变;污染黄土试样的综合结构势先增大后减小,之后再增大再减小。总体而言,重金属Cu^(2+)的掺入,导致土壤pH值降低,主要胶结物质碳酸钙被溶解,而又因黏粒之间的静电引力和范德华力,黏粒聚集体的形态和成分发生变化,从而影响了土体的密实度和结构强度。

5-磷酸吡哆醛缩合罗丹明B席夫碱合成及对Cu^(2+)的识别研究

合成了吡哆醛-5-磷酸罗丹明B席夫碱.通过紫外-可见光光谱法研究了该化合物对Cu^(2+)的识别能力:在丙酮-水(体积比1∶1)混合体系中,加入Cu^(2+)后,在526 nm处出现了一个新的吸收峰,并且随着Cu^(2+)的加入,吸收强度逐渐增强.在(0.25~10)×10^(-6) mol/L的浓度范围内,检测结果呈现出良好的线性关系(R^(2)=0.9993),检测限为2.30×10^(-7) mol/L.

Pretreatment of agricultural residues by supercritical CO_2 at 50–80 °C to enhance enzymatic hydrolysis

Various agricultural crop residues including corn stover,corn cob,and sorghum stalk with a moisture content of 75 wt%were subjected to a long pretreatment(12–60 h)with supercritical CO_2(scCO_2),at low temperature(50–80°C)and a pressure of 17.5–25.0 MPa.The sugar yields from the enzymatic hydrolysis(EH)of the pretreated samples were as much as three-to fourfold greater than those afforded by the raw materials.However,when pretreatment was conducted within a short time(e.g.0.5 h),as previously reported in the literature,only a slight increase in the EH sugar yields was observed.The proposed sc CO_2pretreatment mechanism demonstrated the role of moisture in the system.Wetting,softening,and swelling were observed to mainly affect the lignocellulose when a suitable amount of water was added.Finally,the samples were analysed by X-ray diffraction and scanning electron microscopy,before and after pretreatment,to investigate the changes in the microscopic structure of the biomass.

粉煤灰基P型沸石吸附水中Cu^(2+)和Cd^(2+)

以粉煤灰(FA)为原料经水热反应合成了P型沸石(Z-P).采用X射线荧光光谱仪、X射线衍射仪、场发射环境扫描电子显微镜、比表面孔径分析仪、傅里叶变换红外光谱仪和X射线光电子能谱对Z-P进行表征,并研究了其对Cu^(2+)和Cd^(2+)的吸附性能.结果表明,Z-P的BET比表面积和孔隙体积分别为38.46m^(2)/g和0.2180cm^(3)/g,均高于FA的1.273m^(2)/g和0.0120cm^(3)/g.FA、Z-P对Cu^(2+)和Cd^(2+)的吸附更符合拟二级动力学模型和Langmuir等温线模型.Z-P对Cu^(2+)和Cd^(2+)的最大吸附量分别为157.48,131.57mg/g,远高于于FA的30.88,25.47mg/g.Z-P对Cd^(2+)的循环再生吸附效果好,但对Cu^(2+)的循环再生吸附效果较差.离子强度对Z-P吸附Cu^(2+)和Cd^(2+)分别起促进和抑制作用.表明Z-P可以作为有效且廉价的Cu^(2+)、Cd^(2+)吸附剂,为FA的资源化利用和含Cu^(2+)、Cd^(2+)重金属离子废水吸附剂的开发提供了一种方法.

纳米SiO_(2)粒子表面接枝共聚合物微球的制备及其吸附Cu^(2+)性能

采用KH570对纳米SiO_(2)进行改性,将其作为Pickering乳液的稳定剂;利用反相(Pickering)乳液聚合法制备SiO_(2)@丙烯酰胺(AM)-丙烯酸(AA)共聚物复合微球,并对改性前后纳米SiO_(2)以及复合微球的结构、形貌及质量损失进行了表征;探究pH值、温度和单体比例对复合微球吸附Cu^(2+)效果影响,并对吸附过程进行动力学和吸附等温线拟合。结果表明,改性后的纳米SiO_(2)亲油性增强,提高稳定乳液的能力;Cu^(2+)吸附实验表明,复合微球吸附的最佳pH值为6,且吸附量随着AA用量增加而增大;复合微球吸附Cu^(2+)的过程符合准二级动力学模型和Langmuir模型。