Relationship between breakthrough curve and adsorption isotherm of Ca(Ⅱ)imprinted chitosan microspheres for metal adsorption

In this work, an equilibrium-dispersion model was successfully established to describe the breakthrough performance of Ca（Ⅱ） imprinted chitosan （Ca（Ⅱ）-CS） microspheres packed column for metal adsorption, and the assumptions of Langmuir isotherms and axial dispersion controlled mass transfer process were confirmed. The axial dispersion coefficient in Ca（Ⅱ）-CS microspheres packed column was found to be almost proportional to the linear velocity and fit for prediction through single breakthrough test. Sensitivity analysis for breakthrough curve indicated the axial dispersion coefficient as well as Langmuir coefficient was sensitive variable for deep removal requirement. The retrieval of the adsorption isotherms of Ca（Ⅱ）-CS microspheres from breakthrough curve was fulfilled by modelling calibration. A strategy based on the correlation between adsorption isotherms and breakthrough performance was further proposed to simplify the column adsorption design using absorbents with small/uniform size and fast adsorption kinetics like Ca（Ⅱ）-CS microspheres to cut down the gap between lab and industry.

Fabrication of chitosan microspheres for efficient adsorption of methyl orange

In this article, morphology, structure and size controllable chitosan microspheres with high mechanical strength were synthesized by microfluidic technology combining chemical crosslinking and used as an adsorbent for methyl orange. The synthesized adsorbents were characterized using scanning electron microscopy(SEM),Fourier transform infrared spectroscopy(FTIR), and an Energy Dispersive Spectrometer(EDS). The effect of pH revealed that the adsorption process depended on pH and the pH variation of methyl orange solution after adsorption indicated that adsorption capacity was affected through the associated role of chitosan nature and pH variation. Experimental results suggested that the as-prepared chitosan microspheres were controlled within a narrow size distribution(coefficients of variation is 1.81%), whose adsorption capacity reached to 207 mg·g^(-1) and mechanical strength was suitable to resist forces. In addition, the adsorption isotherm was well fitted with the Langmuir model, and the adsorption kinetic was best described by the pseudo-second-order kinetic model.The high performance microfluidic-synthesized chitosan microspheres have promising potentials in the applications of removing dyes from wastewater.

Comparison of Dye Adsorption of Three Forms of Chitosan

The purpose of this project is to explore the adsorption rates of different dye methods (direct, reactive, acidic, disperse, azo dyes) in three shapes of chitosan materials (film, microsphere, and scaffold) which were formed by 88% deacetylation degree of chitosan. Results of this research suggest that the samples with larger specific surface areas tend to have shorter adsorption times. Among the three samples, the chitosan scaffold reached the adsorptive saturation on the third day, showing the shortest adsorption time of the direct, reactive, acidic, dispersive and azo dyes, whereas the chitosan film reached the adsorptive saturation on the eighth day, giving it the longest adsorption time of the dyes.

Microfluidic synthesis of thiourea modified chitosan microsphere of high specific surface area for heavy metal wastewater treatment

An improved biosorbent of thiourea modified chitosan microsphere（TMCM） with high specific surface,favorable mechanical strength and excellent adsorption performance had been synthesized via microfluidic technology. Polyethylene glycol was used as a significant component added in aqueous solution of chitosan to produce such microspheres through droplets forming, chemical crosslinking and pores creating. For the improvement of adsorption capacity, thiourea was considered as an excellent choice in increasing amino functional group by graft modification. The SEM, FTIR and EDS were employed to detect distinct features of TMCM. Copper（Ⅱ） was used to test the adsorption performance of TMCM. The experimental results indicated that TMCM exhibited higher adsorption capacity（q_e= 60.6 mg g_（-1）） and faster adsorption rate than that non-modified chitosan microsphere（NMCM）.The adsorption kinetic was described well by the pseudo-second order kinetic model, which suggested that chemical adsorption along with electrons transferring was dominant in adsorption process.

Microfluidic synthesis of renewable biosorbent with highly comprehensive adsorption performance for copper （II）

A microsphere biosorbent with uniform size （CV = 1.52%）, controllable morphology and component, and high mechanical strength was synthesized from chitosan by microfluidic technology combining with chemical crosslinking and solvent extraction. This chitosan microsphere （CS-MS） was prepared with a two-step solidification process, which was acquired by drying for the enhancement of mechanical property in final. The adsorption behavior of CS-MS towards copper （II） and main influencing factors on adsorption performance were investigated by batch experiments. Kinetic data high-lighted dominant chemical bonding along with electrons transferring in adsorption process. Isothermal analysis indicated that adsorption capacity was relevant to the number of active site. All these explorations provided a new direction for preparing highly comprehensive performance sorbent used in heavy metal treatment via microfluidic technology.

铜基氮碳微球对废水中盐酸四环素的吸附性能

以水溶性低相对分子质量壳聚糖(0.1000 g)为碳源和氮源,Cu(NO_(3))_(2)·3H_(2)O(0.2174、0.2899、0.6522 g)为铜源,采用一步水热法制备了3种铜基氮碳微球Cu-x/NC(x=1、2、3),通过SEM、FTIR、XRD、Raman光谱和BET对Cu-x/NC进行了表征,通过静态吸附实验考察了Cu-x/NC对盐酸四环素(TC)的吸附性能,并测定了吸附动力学、吸附等温线和吸附热力学参数,测试了Cu-x/NC抗离子干扰、pH稳定性和循环吸附性能。结果表明,Cu-x/NC呈规整的球形结构,表面有含氧和含氮基团,并均匀分布着Cu元素;在25℃吸附温度和24h吸附时间的条件下,Cu-2/NC(5 mg)表现出吸附TC的最大平衡吸附容量(1993.42 mg/g);Cu-2/NC吸附TC符合Langmuir等温线模型和准二级动力学模型,吸附过程是自发、吸热过程;TC溶液中存在NaCl不会降低Cu-2/NC吸附TC的平衡吸附容量,TC溶液在p H=5.5时对吸附最有利;7次循环吸附测试中,Cu-2/NC对TC表现出较为稳定的去除率(95.84%~86.67%);Cu-2/NC吸附TC依靠的主要作用力有氢键、Cu阳离子桥、电子供体-受体相互作用以及静电作用。

壳聚糖/明胶复合微球的制备及吸附性能研究

以壳聚糖和明胶为原料,span 80为乳化剂,戊二醛为交联剂,采用乳化交联法制备了壳聚糖/明胶复合微球并用于Cr(Ⅵ)的吸附。考察了复合微球的各制备因素对微球形貌的影响,通过单因素分析研究了壳聚糖与明胶的比例、乳化剂用量、乳化时间对复合微球吸附性能的影响。结果表明,壳聚糖与明胶的比例为1∶2、span 80用量为6mL、乳化时间为50min时,制备的复合微球对Cr(Ⅵ)的吸附性能良好,吸附量较大,Cr(Ⅵ)的去除率可达95.3%。

Ni^(2+)印迹磁性交联壳聚糖微球的选择性吸附性能

以Ni^(2+)为模板离子、壳聚糖为主要原料、Fe_(3)O_(4)为磁核、环氧氯丙烷为交联剂,制备了Ni^(2+)印迹磁性交联壳聚糖微球。表征结果显示,微球呈现立体结构,表面有较多褶皱,结晶度降低,有利于对Ni^(2+)的吸附。二元金属离子体系的选择性吸附结果表明,等浓度和不同浓度的Ni^(2+)-Cu^(2+)、Ni^(2+)-Zn^(2+)、Ni^(2+)-Cr^(2+)混合溶液中,微球对Ni^(2+)均有较好的选择性吸附性能,随着Ni^(2+)浓度的增加选择吸附系数增大。Ni^(2+)-Zn^(2+)-Cu^(2+)-Cr^(2+)四元金属离子体系的选择性吸附结果表明,微球对Ni^(2+)的平衡吸附量明显大于其他3种金属离子,平衡吸附量的大小顺序为Ni^(2+)>Cu^(2+)>Zn^(2+)>Cr^(2+),Ni^(2+)相对于Cu^(2+)、Zn^(2+)和Cr^(2+)的选择吸附系数分别为81.545、156.529和544.720。

磁性壳聚糖去除水中腐殖酸的研究

采用高温水热法合成了磁性壳聚糖,并研究了其对水中腐殖酸(HA)的吸附、脱附行为。表征结果表明,磁性壳聚糖粒径大小为200～300nm,氨基含量1.29mmol·g-1,BET比表面积36.00m2·g-1,饱和磁化强度为38.78emu·g-1,易于磁性分离。HA在磁性壳聚糖上的吸附等温线可用Freundlich方程模拟,吸附动力学符合拟二级动力学方程。HA的吸附量随溶液pH值的升高而降低,随不同阳离子浓度增加而增加,不同类型的阳离子对HA吸附效果影响的大小顺序为:Ca2+>Mg2+>Na+>K+。经5个脱附再生循环,磁性壳聚糖仍能保持79.8%的吸附量,表明该吸附剂再生性好,可循环使用。

磁性壳聚糖微球吸附水中As(Ⅲ)的实验研究

文章主要考察实验室制得的乙二胺改性磁性壳聚糖微球对毒性高,迁移能力强的A(sⅢ)去除效果。通过单因素实验研究了pH值、吸附时间、A(sⅢ)溶液初始浓度和吸附剂投加量对磁性壳聚糖微球吸附除A(sⅢ)效果的影响。实验结果表明在pH值为2,吸附时间为90 min,磁性壳聚糖微球投加量为0.4 g时,对初始浓度为10 mg/L,体积为100 mL的A(sⅢ)溶液去除率达到96.96%,吸附后溶液中A(sⅢ)浓度仅为0.304 mg/L,低于我国污水综合排放标准中砷含量标准值。磁性壳聚糖微球的解吸实验表明,吸附剂解吸4次后,对A(sⅢ)的去除率仍达到95%以上,吸附性能稳定,具有较好的可重复利用性。因此,磁性壳聚糖微球是一种去除低浓度含砷废水非常有效的材料。

交联壳聚糖磁性微球的制备及其对金属离子的吸附性能

以碳包铁作磁核,环氧氯丙烷作交联剂,通过反相悬浮交联法制备交联壳聚糖磁性微球,研究磁性微球对Cu2+和Pb2+的吸附性能和吸附机理.结果表明:磁性微球对Pb2+和Cu2+的吸附量分别为72.0mg.g-1和48.3mg.g-1,磁性微球具有不易流失,易再生的特点.

交联羧甲基壳聚糖微球的制备及其对Pb^(2+)的吸附性能

保护氨基的壳聚糖微球经环氧氯丙烷交联得到不溶于酸的吸附剂 ,与氯乙酸在碱性条件下反应 ,合成了羧甲基壳聚糖树脂 ,并用FT IR对树脂进行了表征。其吸附Pb2 + 的实验结果表明 ,在 1h内有最快的吸附速率 ,吸附受pH值影响。在pH =5时 ,对Pb2 + 的吸附量为 1 12mmol g ,比壳聚糖树脂提高了 70 %。

球形改性壳聚糖的制备及吸附牛血清蛋白性能的研究

采用反相悬浮交联法制备了壳聚糖多孔微球树脂,讨论了交联剂环氧氯丙烷浓度、致孔剂PEG2000浓度对成球性能的影响.红外光谱、光学显微镜和扫描电镜的结果表明,树脂为蜂窝状多孔微球,色泽好,粒度均匀,阴离子交换容量为3-4mmol/g,不溶于水、酸、碱.从吸附牛血清蛋白（BSA）的实验发现,交联剂浓度对吸附有很大影响,交联浓度为0.04 mol·L-1时得到的微球树脂对牛血清蛋白有较好的吸附,其饱和吸附容量达到 116mg/g.

磁性壳聚糖微球吸附苹果渣多酚的动力学及热力学分析

为了更好的利用胺基化磁性壳聚糖微球吸附分离苹果渣多酚的工艺,对其反应动力学和热力学进行了研究。主要采用Langmuir准一级动力学模型、Langmuir准二级动力学模型、Elovich方程及内扩散方程对吸附反应动力学过程进行拟合,并利用Langmuir等温吸附模型、Freundlich等温吸附模型及Temkin等温吸附模型对吸附反应热力学特性进行解析。结果表明:吸附动力学过程符合准二级动力学模型的描述,吸附温度越高,吸附速率常数和初始吸附速率越大,且平衡吸附量越高。吸附热力学过程符合Freundlich等温吸附模型,热力学参数ΔG<0,ΔH>0,ΔS>0,表明胺基化磁性壳聚糖微球对苹果渣多酚的吸附过程可以自发进行,并且是伴随着焓变>0的吸热过程。动力学及热力学研究为利用胺基化磁性壳聚糖微球进行苹果渣多酚的提取分离提供了技术依据。

球状壳聚糖树脂的制备及其吸附热力学研究

研究1种球状壳聚糖树脂(RCM)吸附Cu2+的热力学行为,为RCM应用于除去废水、果蔬汁等中的重金属离子提供理论基础。首先壳聚糖为原料采用反相悬浮交联法制备RCM,并表征了RCM的一些物理化学性质;其次采用静态吸附法研究RCM对Cu2+的吸附行为。结果发现,制得的RCM粒径较为均一,且表面致密多孔,其含水量为51.982%,树脂骨架密度(ρT)为1.212 g.cm-3,堆砌密度(ρp)为0.862 g.mL-1,孔度值(P)为0.554,交联度为13.581%。RCM对Cu2+饱和吸附量为0.993 mmol.g-1,吸附等温线符合Langmiur等温曲线,其Langmiur等温式为:Ce/Q=11.614+1.007 5Ce(313K),表明其对Cu2+属于单分子层吸附。吸附热力学研究表明:吸附是自发的、吸热的、熵增加的过程。通过吸附势值可知,在相同的温度下,随着溶液中Cu2+浓度的增加,吸附势逐渐降低;当初始浓度相同时,随着实验温度的升高,吸附势升高。

改性壳聚糖微球合成及对Cu^(2+)吸附性能的研究

壳聚糖由于其结构特性和表面化学性能,对过渡金属离子有很强的亲和力和良好的选择性。利用二乙胺、三乙胺、聚乙烯亚胺(PEI)对壳聚糖微球进行改性,增加壳聚糖微球的活性中心以强化对二价铜离子(Cu^(2+))的吸附能力。实验结果表明:在Cu^(2+)溶液pH为5,吸附时间为15min,温度为35℃时,制得的改性壳聚糖微球对Cu^(2+)的吸附量达到2.88mmol/g。

壳聚糖键接β-环糊精微球的制备及其对甲基橙的吸附性能

用壳聚糖键接β-环糊精微球,合成了具有良好吸附效果的天然高分子絮凝剂.利用X-射线衍射仪、傅里叶变换红外光谱仪、扫描电镜和比表面孔径测定仪表征原料和产物的结构和微观形貌,通过改变搅拌时间、温度、pH值和甲基橙溶液质量浓度等实验条件,比较原料和键接产物对甲基橙溶液的吸附性能.结果表明,壳聚糖键接β-环糊精微球与β-环糊精微球和壳聚糖相比,吸附性能更为优异,且键接产物的吸附量随温度和pH值升高而增大,最大吸附量达到20mg·g-1,其吸附过程符合Freundlich吸附模型,是非自发的吸热过程.

酮戊二酸改性壳聚糖微球的制备及吸附性能

采用反相悬浮法制备交联壳聚糖微球,再与α-酮戊二酸反应生成Schiff碱,NaBH4还原制得改性壳聚糖微球。用FT-IR、SEM和XRD进行表征,并用于吸附2,4-二硝基酚研究。考察了吸附时间、溶液pH值、2,4-二硝基酚浓度、温度、NaCl含量等因素对吸附的影响。结果表明,α-酮戊二酸改性交联壳聚糖微球对2,4-二硝基酚有较好的吸附性能,在pH为3.6时,30 min吸附量达372.2 mg/g,吸附数据符合Freundlich等温方程。

胺基化磁性壳聚糖微球对苹果渣多酚的吸附条件优化

为分离苹果渣中的多酚物质,研究壳聚糖磁性材料对多酚物质提取的影响。采用化学共沉淀法制得Fe3O4磁核,反相悬浮交联法制得磁性壳聚糖微球,并进行胺基化改性;利用扫描电镜、激光粒度仪对微球进行表征。采用单因素试验和响应曲面法对磁性微球吸附分离苹果渣多酚的吸附条件进行了工艺优化。结果表明:胺基化磁性壳聚糖微球吸附苹果渣多酚工艺参数对多酚吸附率有显著影响,因素影响主次顺序为微球用量>摇床转速>吸附温度;胺基化磁性壳聚糖微球吸附苹果渣多酚的工艺参数为:微球用量0.25g/mL,吸附温度45℃,摇床转速127r/min,吸附率可达81.58%。壳聚糖与Fe3O4磁性物质相结合,对多酚物质具有良好的吸附性能,可以对多酚物质进行快速分离,解析后多酚得率可达78.73%。研究结果为磁性材料吸附分离多酚类物质提供了理论参考。

碳纳米管/活性炭复合微球的制备及其对VB_(12)的吸附应用

采用反相乳液法制备碳纳米管/壳聚糖复合微球(CNTs/CTS),并对其进一步炭化、活化制得碳纳米管/活性炭复合微球(CNTs/AC).以此复合微球为吸附材料,探索了其对中分子代表物质VB12的吸附.研究结果表明,碳纳米管含量70%(w)的复合微球经水蒸气适当活化后球形度好、吸附性能优异,其对VB12的吸附量达23.59mg·g-1,分别是活性炭和大孔吸附树脂的5.4和2.7倍.分析表明这是由于碳纳米管/活性炭复合微球具有发达的中孔结构.