高岭土负载改性壳聚糖重金属吸附剂性能研究

壳聚糖是一种来源广泛、无毒、易降解的天然高分子材料,其分子中的羟基和氨基等官能团能与重金属离子进行螯合吸附。该研究充分利用高岭土高机械强度及多孔结构的特点,在其孔道结构中负载对重金属离子具有选择性吸附作用的改性壳聚糖,对解决传统改性壳聚糖在重金属污水处理中成本过高问题具有重要意义。通过超声和高温搅拌作用,在高岭土中负载改性壳聚糖合成新型的重金属吸附剂,幵针对其对污水中的Cu~(2+)、Mn~(2+)、Ni~(2+)、Pb~(2+)、Zn~(2+)等重金属离子的吸附效果、吸附性能及最佳吸附条件等进行了相应研究和应用前景展望。     

氨基化改性壳聚糖磁性树脂的原位制备及其对UO_2~(2+)的吸附性能

利用NaOH/Fe~(2+)反应体系生成Fe(OH)_2,同时通入低浓度O_2使Fe(OH)_2氧化成Fe_3O_4,在壳聚糖基质内部均匀生成磁性物质;并利用三聚磷酸钠交联,原位制备氨基化改性磁性壳聚糖树脂(TETA-MCR)。考察了不同pH、吸附时间、初始浓度及温度对TETA-MCR吸附UO_2~(2+)性能的影响。FT-IR分析表明氨基是UO_2~(2+)主要吸附位,通过配位络合吸附UO_2~(2+)。吸附动力学符合拟二级动力学模型,并且为自发吸热过程。吸附等温线符合Langmuir模型,298 K时最大吸附容量达166.6 mg UO_2~(2+)×g~(-1)。TETA-MCR对UO_2~(2+)吸附具有吸附容量较高、易于磁分离、可重复使用的优点,可作为UO_2~(2+)分离的新型磁性吸附剂。     

分子印迹强化胺化改性壳聚糖吸附Cd~(2+)性能研究

利用分子印迹强化胺化技术制备Cd~(2+)模板改性壳聚糖P(Cdb2+)-C-CTS(Cda2+),研究了吸附剂中Cd~(2+)模板含量对其吸附水中Cd~(2+)的性能及含水率的影响。吸附容量随着a值和b值的增加而升高,当a为0.45、b为0.40时,吸附容量达到最大值。以P(Cd0.402+)-C-CTS(Cd0.452+)为研究对象,考察了p H对Cd~(2+)吸附容量的影响,并对吸附选择性能进行研究。结果表明,分子印迹强化胺化技术可制备得到吸附效率更高、选择性更好的改性壳聚糖吸附剂。     

聚多巴胺包覆的磁性碳纳米管对水中Ni~(2+)的吸附作用

以碳纳米管(MWNTs)、多巴胺、硫酸亚铁铵、硫酸铁铵为主要原材料,采用化学共沉淀法制备磁性碳纳米管(mMWNTs),通过多巴胺原位氧化聚合到磁性碳纳米管表面上,生成改性材料聚多巴胺(PDA)包覆的磁性碳纳米管(mMWNTs@PDA)。并采用红外光谱(FTIR)、扫描电镜(SEM)对其进行表征。考察了改性后材料在pH、反应时间、温度、初始浓度因素下对水中Ni⁽²⁺⁾的吸附,同时对吸附数据进行吸附动力学和吸附等温线分析。结果表明,改性材料对水溶液中Ni(2+)的吸附,同时对吸附数据进行吸附动力学和吸附等温线分析。结果表明,改性材料对水溶液中Ni⁽²⁺⁾的吸附过程更符合准二级动力学模型(R(2+)的吸附过程更符合准二级动力学模型(R²=0.998 9)和Freundlich等温吸附模型(R2=0.998 9)和Freundlich等温吸附模型(R²=0.996 1)。最后考察改性材料的重复利用性能,实验结果证明经循环再生5次后仍然具有较好的吸附性能。     

Cu~(2+)印迹磁性壳聚糖微球的表征及吸附性能

以磁性Fe_3O_4为磁核,Cu~(2+)为模板离子,壳聚糖为功能单体,制备了Cu~(2+)印迹磁性壳聚糖微球(MIPs)。采用透射电镜、红外光谱分析、振动样品磁强计和X射线衍射仪对MIPs进行表征。结果表明,MIPs具有三维网状的多孔结构,并且Fe_3O_4被壳聚糖包埋且分布均匀。同时通过振动样品磁强计测得其饱和磁化强度为10.8 emu×g~(-1),具有一定的磁性能。采用静态吸附法研究了MIPs对Cu~(2+)的吸附。结果表明,最佳吸附p H值为5;吸附3 h达到吸附平衡;MIPs对Cu~(2+)的吸附符合准二级动力学方程。并对MIPs的选择识别能力进行了评价,结果表明:MIPs对Zn~(2+)、Co~(2+)、Ni~(2+)的相对选择性系数K'分别为2.07、2.59、3.44,对Cu~(2+)具有较高的选择识别性能。并且,MIPs再生-重复使用10次吸附容量没有明显的降低。     

磁性有机膨润土的制备及其吸附性能研究

采用共沉淀法制备Fe_3O_4磁流体,用磁流体与乙二胺四乙酸二钠复合改性有机膨润土制备Fe_3O_4负载的改性磁性有机膨润土,并对其进行了红外光谱分析、扫描电子显微镜形貌分析、元素分析,测定了样品对不同基材上Pb~(2+)、Cr~(6+)吸附剩余量。结果表明,Fe_3O_4微粒能够负载到被乙二胺四乙酸二钠改性过的有机膨润土表面形成磁性集合体,改性磁性膨有机润土具有良好的超顺磁性,对Pb~(2+)、Cr~(6+)等核素有良好吸附性能,从而达到去除放射性核素的目的。     

功能化壳聚糖磁性微球的制备及其对Cr~(3+)、Ni~(2+)的吸附

以经SiO_2包覆的Fe_3O_4和4-氯苯基异氰酸酯修饰的壳聚糖为原料,六亚甲基双异氰酸酯(HDI)为连接剂,制得功能化Fe_3O_4@Si O_2-壳聚糖磁性微球(磁性微球C),并利用SEM、FTIR对其进行表征,考察了所得磁性微球C对Cr~(3+)和Ni~(2+)的吸附性能。结果表明:磁性微球C的平均粒径为520 nm左右且分散性好。对Cr~(3+)、Ni~(2+)的吸附在60 min内达到平衡,在吸附剂质量为0.2 g,Cr~(3+)浓度为2.5 mmol/L,p H=3.0时,Cr~(3+)的单位吸附量为191.1 mg/g;在Ni~(2+)浓度为0.1 mmol/L,pH=5.0时,Ni~(2+)的单位吸附量为4.725 mg/g。所测等温吸附数据既符合Langmuir模型,也符合Freundlich模型。     

聚多巴胺包覆的磁性碳纳米管对水中Ni~(2+)的吸附作用

以碳纳米管(MWNTs)、多巴胺、硫酸亚铁铵、硫酸铁铵为主要原材料,采用化学共沉淀法制备磁性碳纳米管(mMWNTs),通过多巴胺原位氧化聚合到磁性碳纳米管表面上,生成改性材料聚多巴胺(PDA)包覆的磁性碳纳米管(mMWNTs@PDA)。并采用红外光谱(FTIR)、扫描电镜(SEM)对其进行表征。考察了改性后材料在pH、反应时间、温度、初始浓度因素下对水中Ni~(2+)的吸附,同时对吸附数据进行吸附动力学和吸附等温线分析。结果表明,改性材料对水溶液中Ni~(2+)的吸附过程更符合准二级动力学模型(R~2=0.998 9)和Freundlich等温吸附模型(R~2=0.996 1)。最后考察改性材料的重复利用性能,实验结果证明经循环再生5次后仍然具有较好的吸附性能。     

壳聚糖处理污水中的Pb~(2+)优化条件研究

壳聚糖由于其优良的吸附、螯合性能在水质净化领域已显示出了其广泛的应用前景。本课题主要是对壳聚糖处理污水中的Pb~(2+)优化条件研究。分别在不同壳聚糖用量、反应时间、反应温度、反应pH值等条件下,进行壳聚糖吸附Pb~(2+)反应,然后测定吸附后的Pb~(2+)浓度。得出壳聚糖吸附铅离子反应优化条件。进行壳聚糖的解吸附实验,验证壳聚糖的再生性能。     

交联壳聚糖凝胶溶胀性能及Ni(Ⅱ)吸附效果研究

以壳聚糖为原料,戊二醛为交联剂制备交联壳聚糖凝胶,并对凝胶的溶胀性能及Ni~(2+)吸附效果进行研究。实验结果表明,交联剂用量越大,交联密度越高,但是凝胶网络弹性降低,溶胀性变差;弱酸至中性条件有利于凝胶的溶胀,交联改性能降低壳聚糖的溶胀热敏温度,降低后期吸附Ni~(2+)的能耗。用1%的戊二醛交联壳聚糖处理20、40 mg/L Ni~(2+)电镀废水,投加60 mg交联改性壳聚糖,在30℃、p H=7条件下吸附3 h,吸附率分别达96.9%和92.4%,吸附过程可用一级动力学模型进行模拟。废水经过二次吸附后出水水质均能达到0.01 mg/L Ni~(2+)的《污水综合排放标准》(GB3838)标准,交联改性壳聚糖的重复使用性好,多次循环使用后依然具有很好的吸附效果。     

硫脲改性磁性壳聚糖微球对Hg2+的吸附特性

利用悬浮分散以及化学交联技术制备磁性壳聚糖微球,并经硫脲改性(SMCS),用于吸附水溶液中Hg2+。用光学显微图、红外、热重分析等对微球进行了表征;考察了pH值、Hg2+初始浓度、吸附时间以及振荡速率对Hg2+吸附的影响。结果表明,SMCS为球形,粒径50—80μm。SMCS对Hg2+有良好的吸附性能,饱和吸附容量(1.2—6.5 mmol/g)随pH值升高而增加,pH值为5.0时饱和吸附容量约为2.9 mmol/g。等温吸附线可用Freundlich等式拟合。吸附动力学结果表明,振荡速率为150—200 r/min时,为内扩散控制;50—150 r/min时,由外扩散和内扩散同时控制;振荡速率<<50 r/min时,为外扩散控制。吸附动力学可用拟二级模型拟合,初始吸附速率为0.22—1.77 mmol/(g.h),随振荡速率加快而增加。     

壳聚糖复合材料对废水中汞离子的吸附

以壳聚糖为基质,通过化学键合方法制备了铝涂覆的壳聚糖-铝氧化物复合材料;发现其对水溶液中的汞离子具有较好的吸附性能,研究了反应温度、时间、溶液起始浓度等条件对吸附性能的影响;壳聚糖复合材料对汞离子的吸附量随反应温度的升高而增大,以化学吸附为主;随着溶液中离子的起始浓度的增大,吸附量迅速增加,而吸附率则下降;对于低浓度的溶液,常温下吸附率可达90%以上,而对于浓度较高的溶液,吸附量高达900 mg/g以上;与未改性的壳聚糖及无机氧化铝相比,壳聚糖复合材料对汞离子的吸附性能得到明显改善;壳聚糖经改性后,热稳定性也得到了显著提高.     

微波辐射下香草醛改性壳聚糖的制备及其对金属离子的吸附

应用微波辐射法合成了香草醛接枝壳聚糖,用NaBH4进行还原。探讨了改性壳聚糖在25℃下对Ni2+、Mn2+、Cr6+的吸附及时间、离子浓度、pH值对吸附效果的影响。结果表明,还原后的改性壳聚糖比壳聚糖吸附性能明显改善,其对Ni2+、Mn2+和Cr6+的吸附容量分别可以达到116.23,63.83,47.27 mg/g。     

CoFe2O4-PPy@CS磁性纳米材料制备及吸附研究

用聚吡咯(PPy)和壳聚糖(CS)功能化CoFe2O4,制得CoFe2O4-PPy@CS磁性纳米复合材料。对所得材料的形貌和结构进行表征,并研究了不同环境参数对复合材料吸附Cu^2+、孔雀石绿(MG)和甲基蓝(MB)的影响。结果表明,复合材料吸附Cu^2+和MG(MB)的适宜pH分别为5~7、5~9;随着时间的延长,对Cu^2+、MG、MB的吸附量均逐渐增加,MB的吸附速率要明显快于Cu^2+和MG,并于120 min左右达到吸附平衡,而Cu^2+和MG则需要更长的平衡时间。对Cu^2+的吸附符合Langmuir等温线模型,对MG的吸附符合Freundlich等温线模型,且2种吸附等温线模型均能较好地拟合对MB的吸附过程,最大吸附量分别可达48.3、246.0、233.8 mg/g。三者的吸附动力学均遵循准2级动力学反应模型。     

交联壳聚糖微球对喹乙醇吸附性能的研究

以壳聚糖为原料,乙酸乙酯为致孔剂,环氧氯丙烷为交联剂,通过交联法制备出改性壳聚糖,考察了交联壳聚糖微球对喹乙醇吸附的影响。结果表明,V(壳聚糖)∶V(乙酸乙酯)∶V(环氧氯丙烷)=30∶1∶1时,制备的交联壳聚糖微球对喹乙醇吸附性能较好;红外光谱表明,环氧氯丙烷与壳聚糖发生反应;扫描电镜分析验证环氧氯丙烷用量对交联壳聚糖微球吸附性能有一定影响;吸附动力学曲线得知交联壳聚糖微球在3 h对喹乙醇吸附达到平衡,有较好的吸附速度;与类似物(喹烯酮和乙酰甲喹)吸附特性比较得知,交联壳聚糖微球对喹乙醇有较好的选择吸附性。     

改性大豆皮吸附剂对Pb2+的生物吸附性能研究

Using soybean hull residue after the soluble dietary fiber being removed during the soybean processing industry as crude material,a novel absorbent,modified soybean hulls,is prepared.Its adsorption behavior for Pb2+ is studied.The adsorbent has a large and efficient adsorption capacity for Pb2+,up to 20% of the mass of dry ad-sorbent.Its maximum adsorption capacity for Pb2+ reaches 217 mg·g-1 at initial Pb2+ concentration of 2000 mg·L-1,which is twice that of yeast absorbent and threefold greater than that of chitosan absorbent.The adsorption ability is sensitive to pH value in the solution and the optimal pH for adsorption of Pb2+ is 7.0.In the presence of other metal ions (Ca2+,Mg2+ and Na+) in the solution,their effect on the adsorption capacity for Pb2+ is not obvious.After 5 cy-cles of adsorption,80% adsorption capacity of Pb2+ is maintained.Compared with various available commercial resins,the modified soybean hulls are a plentiful,inexpensive and effective medium for the capture of dissolved Pb2+ from waste streams.     

Cu2+ removal from aqueous solution by modified chitosan hydrogels

BACKGROUND: The adsorption of Cu²⁺ from aqueous solution using crosslinked chitosan hydrogels impregnated with Congo Red (CR) by ion‐imprint technology was systematically investigated with particular reference to the effects of contact time, pH, and initial concentration on adsorption. RESULTS: The adsorption capacity of the crosslinked chitosan without impregnation was only 68.68 mg g^?1 for Cu²⁺. However, the adsorption capacity increased from 77.42 (without imprint ion) to 84.54 mg g^?1 (imprint ion content 0.5 mmol) after the chitosan was impregnated with a ratio of 1/12 of CR to chitosan. The as‐prepared adsorbents were found to be pH‐dependent and the process of adsorption agreed well with the Freundlich isotherm. The loaded adsorbents could be regenerated and reused without the appreciable loss of capacity. CONCLUSION: Chitosan hydrogels impregnated with CR showed higher Cu²⁺ adsorption capacities compared with those prepared conventionally without imprint ion, and thus developed a good approach to increase Cu²⁺ adsorption efficiency in the treatment of waste‐water. Copyright © 2012 Society of Chemical Industry     

Removal of Hg2+ from aqueous solution using a novel composite carbon adsorbent

A novel composite carbon adsorbent (GCA) has been prepared by immobilizing activated carbon and genipin‐crosslinked chitosan into calcium alginate gel beads via entrapment and applied to the removal of mercury (Hg²⁺) ions from aqueous solution (e.g., drinking water). Two bead sizes and two mixing ratios of components were obtained and characterized. Batch experiments were performed to study the uptake equilibrium and kinetics of Hg²⁺ ions by the GCA. The Hg²⁺ adsorption capacity of GCA was found to be dependent of pH and independent of size of the adsorbent. The Hg²⁺ adsorption rate of GCA increases with decreasing its bead size. However, both adsorption capacity and rate of GCA for Hg²⁺ increase with increasing its chitosan content. Otherwise, it was shown that the GCA has higher Hg²⁺ adsorption capacity and rate than activated carbon, which might be caused by the incorporation of chitosan into the GCA. The maximum Hg²⁺ adsorption capacity of GCA was found to be 576 mg/g, which is over seven times higher than that of activated carbon. Our results reveal the uniform distribution of activated carbon and chitosan within the alginate gel bead and that Hg²⁺ ions can diffuse inside the bead. It also demonstrated the feasibility of using this GCA for Hg²⁺ removal at low pH values. The Hg²⁺ absorbed beads of the GCA can be effectively regenerated and reused using H₂SO₄. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Effects of Acylation and Crosslinking on the Material Properties and Cadmium Ion Adsorption Capacity of Porous Chitosan Beads

Abstract

Chitosan is a novel glucosamine biopolymer derived from the shells of marine organisms. This biopolymer is very attractive for heavy metal ion separations from wastewater because it is selective for toxic transition metal ions over less toxic alkali or alkane earth metal ions. Highly porous, 3-mm chitosan beads were prepared by an aqueous phase-inversion technique for casting gel beads followed by freeze drying. In the attempt to simultaneously improve material properties and adsorption capacity, chitosan was chemically modified by 1) homogeneous acylation of amine groups with nonanoyl chloride before bead casting, and 2) heterogeneous crosslinking of linear chitosan chains with the bifunctional reagent glutaric dialdehyde (GA) after bead casting but before freeze drying. The random addition of C₈ hydrocarbon side chains to about 7% of the amine groups on uncrosslinked chitosan beads via N-acylation improved the saturation adsorption capacity from 169 to 216 mg Cd²⁺/g-bead at saturation (pH 6.5, 25°C) but only slightly reduced solubility in acid solution. Crosslinking of the N-acylated chitosan beads with 0.125 to 2.5 wt% GA in the crosslinking bath increased the internal surface area from 40 to 224 m²/g and rendered the beads insoluble in 1 M acetic acid (pH 2.36). However, crosslinking of the N-acylated chitosan beads reduced the saturation adsorption capacity to 136 mg Cd²⁺/g-bead at 0.75 wt% GA and 86 mg Cd²⁺/g-bead at 2.5 wt% GA. Crosslinking also significantly reduced the compression strength. There was no clear relationship between internal surface area and adsorption capacity, suggesting that the adsorbed cadmium was not uniformly loaded into the bead.