聚天冬氨酸/木质纤维素水凝胶的制备及吸附性能

采用水溶液聚合法合成聚天冬氨酸（PASP）/木质纤维素（LNC）水凝胶;考察了预处理时间、预处理温度、KMnO₄浓度、戊二醛用量、PASP的用量、反应时间以及反应温度对PASP/LNC水凝胶吸附Pb2+、Cd2+性能的影响;运用Langmuir吸附等温线计算PASP/LNC水凝胶最大吸附量;使用HNO₃对PASP/LNC水凝胶进行脱附再生实验;采用SEM和FTIR对水凝胶的结构进行表征。吸附结果表明:预处理时间15 min,预处理温度50 ℃、KMnO₄浓度0.06 mol·L-1、戊二醛用量1.00 g、PASP用量11 g、反应时间3.5 h且反应温度70 ℃时,对Pb2+、Cd2+的平衡吸附容量分别为980.39 mg·g-1、813.01 mg·g-1。 吸附/脱附循环实验表明:循环吸附脱附4次后PASP/LNC水凝胶吸附量仍较高,PASP/LNC水凝胶是一种可循环利用的吸附剂。表征结果表明:PASP/LNC水凝胶的表面有大小不等的孔隙,PASP的—COOH与LNC的O—H发生缩聚反应,形成具有三维网络结构的水凝胶。      

聚天冬氨酸/木质纤维素水凝胶对Pb(Ⅱ)的吸附及脱附性能

以聚天冬氨酸(PASP)与木质纤维素(LNC)水溶液聚合法制备出的聚天冬氨酸/木质纤维素水凝胶(PASP/LNC)为吸附剂,对Pb(Ⅱ)进行吸附及脱附实验,研究溶液的初始离子浓度、pH值、吸附时间和吸附温度对溶液中Pb(Ⅱ)吸附量的影响。结果表明,溶液中Pb(Ⅱ)初始离子浓度为0.04 mol/L,溶液pH值为5.5,吸附时间为120 min,吸附温度为30℃时,PASP/LNC水凝胶对Pb(Ⅱ)的吸附量达到最大为972.35 mg/g。吸附过程符合准二级动力学模型,吸附等温线符合Langmuir模型。采用X射线衍射分析、比表面积和平均孔径分析、扫描电镜、傅里叶变换红外光谱分析PASP/LNC水凝胶的结构和吸附机理。使用HNO_3对PASP/LNC进行脱附实验。结果表明,HNO_3浓度为0.04 mol/L,脱附温度为30℃,脱附时间达到60 min时,最大脱附量为928.36 mg/g。吸附/脱附循环实验表明,PASP/LNC水凝胶重复使用4次后吸附量仍较高,是一种可重复使用的高效吸附材料。     

氧化石墨烯/海藻酸钙水凝胶复合膜对水中Cd(II)的吸附

将氧化石墨烯(GO)、致孔剂与海藻酸钠共混后与CaCl₂交联制备的GO/海藻酸钙（CA）水凝胶复合膜作为含重金属废水的吸附材料。采用SEM和TEM表征了复合膜的表面形貌及透射性能,且分析了GO的加入对复合膜的力学性能、平均孔径、水通量及表面官能团的影响。为探究GO/CA水凝胶复合膜的吸附性能,考察了其吸附Cd(II)的影响因素:pH（6~7）值、初始离子浓度、接触时间、温度（三者均正相关）。用FTIR、XPS在吸附前后对复合膜进行了表征;引入了吸附动力学和等温线模型分析其吸附机制。探究结果表明GO的加入提高了复合膜的力学性能、平均孔径及水通量;吸附过程遵循Langmuir等温线,属于单层吸附,拟合得到的最大吸附量为173.61 mg/g;伪一级和伪二级吸附动力学分别在低浓度和高浓度时能较好地描述吸附过程的动力学行为;吸附机制主要为物理作用力吸附和离子交换。经过5个连续的吸附-解吸循环证明了GO/CA水凝胶复合膜的可重复利用性。      

丙烯酰胺-衣康酸聚合物水凝胶的制备及吸附重金属研究

随着重金属的开采、冶炼以及加工,越来越多重金属进入土壤、水体中,这不仅造成严重的环境污染问题,还对人类的健康造成严重的危害。因此,研究对重金属污染的治理至关重要。本研究采用自由基共聚的方法以丙烯酰胺(AM)和衣康酸(IA)为原料合成交联聚合物水凝胶AM-co-IA,应用红外(FT-IR)和热重手段对水凝胶进行了表征。研究了不同原料组成的水凝胶对重金属离子吸附量的影响,并考察了溶液pH值、重金属初始浓度对重金属吸附量的影响。竞争吸附结果表明:聚合物水凝胶AM-co-IA对5种重金属离子的吸附顺序依次是:Cr(III)Pd(II)Cu(II)≈Ni(II)Cd(II)。     

壳聚糖/木质素磺酸钠吸附剂的制备及其除Pb2+和Cd2+

工业废水给水体和土壤带来巨大的灾害,严重影响农作物的生长.为了获得洁净水,须制备一种稳定、有效、可持续的处理剂来控制水污染.使用木质素磺酸钠和壳聚糖,以自由基聚合法在聚丙烯酸上制备木质素基水凝胶吸附剂,并将其应用于除去Pd2+和Cd2+.采用正交法对木质素磺酸钠、壳聚糖、交联剂以及引发剂的含量进行优化.分别利用傅里叶红外光谱仪、扫描电镜图、热分析仪以及Zeta电位仪对吸附剂进行表征.探究不同条件对木质素基水凝胶吸附Pb2+和Cd2+的影响,在此基础上建立动力学和等温线模型.结果表明:在吸附剂为0.015 g、重金属离子浓度为100 mg·L-1、pH值为7时,对Pd2+的吸附容量为367 mg·g-1,对Cd2+的吸附容量为296 mg·g-1.同时,揭示木质素基水凝胶剂的吸附过程是一种以静电吸附为辅、化学吸附为主的吸附模式.     

双网络微球水凝胶对Cu2+的吸附行为研究

工业的迅速发展导致水体环境污染问题也愈加严重，针对重金属废水的处理极为迫切。以海藻酸钠微球为基质，合成出海藻酸钙和聚丙烯酰胺双网络结构的NH₂-SA/PAM微球水凝胶。通过扫描电镜、红外光谱、X射线光电子能谱(XPS)等手段表征可知，该凝胶具有多孔网络结构，具有大量的羟基、氨基等活性位点，能实现离子在凝胶内部的快速扩散。通过对Cu²⁺的吸附实验可知，NH₂-SA/PAM微球水凝胶具有较好的吸附性能，基于Langmuir模型，在30℃下q_max为265.31mg/g,在100min内便达到吸附平衡的80%,通过均相表面扩散模型(HSDM)其凝胶内部的扩散系数D_s为2.83×10^-11m/s。该NH₂-SA/PAM对Pb²⁺、Cd²⁺、Zn²⁺、Mn²⁺、Ni²⁺和Cu²⁺均有较好的吸附性能，其分配系数与离子...     

生物炭-膨润土共改性及其铅离子吸附与稳定化研究

重金属污染具有高毒性、持久存留和生物积累等特性, 严重危害人体健康和生态安全。本研究通过氯化钙对玉米芯残渣和膨润土混合物进行碱改性, 在无氧条件下高温煅烧制备了一种碱改性生物炭-膨润土复合物(CaO-Bent-CB)。该复合物的比表面积高, 达到441.1 m²/g, 明显高于直接煅烧制备的生物碳(132.7 m²/g)和碱改性生物炭(177.2 m²/g)。进一步评价了该复合物对水中铅离子吸附性能, 结果表明在水中铅离子浓度为120 mg/L, 膨润土与玉米芯残渣质量比为1:5, 用量为1 g/L条件下, 吸附6 h后铅离子去除率达98%, 吸附量为109.6 mg/g, 均高于生物炭(13.4 mg/g)、膨润土(72.9 mg/g)和碱改性生物炭(86.9 mg/g)。此外, 采用CaO-Bent-CB对铅离子污染土壤进行稳定化处理, 当土壤中铅离子浓度为2200 mg/kg, CaO-Bent-CB用量为土壤干重的8%时, 在pH=3.2的硫酸-硝酸浸提液中浸出12 h, 酸浸出铅离子浓度低至4.5 mg/L, 低于危险废物鉴别标准值(5 mg/L)。上述研究结果表明这种生物炭-膨润土共改性复合物在重金属污染水体和土壤修复中具有很好的应用前景。     

纳米氧化石墨烯复合材料的制备及重金属废水处理研究

以改进的Hummers法制备了纳米氧化石墨烯(GO),以乙二胺四乙酸(EDTA)为改性剂，制备了功能化GO复合材料。通过XRD、SEM、FT-IR对功能化GO复合材料的晶格结构、微观形貌和官能团进行了表征，并以此作为吸附剂，测试了不同pH值、初始浓度、吸附时间等吸附环境对含Cd的重金属废水吸附性能的影响。结果表明，EDTA表面具有丰富的羟基、羧基等含氧基团，嫁接到GO表面后使GO表面的活性点位增多，Cd(Ⅱ)被功能化GO复合材料表面的活性点位所吸附后沉积在了原有的沟槽中，使复合材料的表面变得光滑。当pH=6时，功能化GO复合材料对含Cd重金属废水的吸附容量和去除率达到最大值，分别为45.8 mg/g和95.3%;在初始浓度为120 mg/L时，吸附容量和去除率达到了最大值，分别为66.5 mg/g和96.3%;在吸附时间为60 min时，可达饱和吸附，吸附容量和去除率达到最高值，分别为78.0 mg/g和98.5%。经过5次重复使用后，吸附容量可保持在23.8 mg/g,去除率保持在85.4%,具有优异的循环性能。     

POSS杂化聚丙烯酰胺/PU复合水凝胶的制备及其对Pb~(2+)吸附性能研究

采用POSS杂化聚丙烯酰胺(PAM-co-OVPOSS)和聚丙烯酰胺(PAM)为交联剂,分别与PU作用形成交联网络结构,制备PAM/PU和PAM-co-OVPOSS/PU复合水凝胶。通过对比分析,详细探讨分子结构、溶液浓度等对凝胶性能的影响,使用扫描电镜(SEM)、红外光谱(FT-IR)、万能试验机对水凝胶的结构以及力学性能进行详细表征研究发现PAM/PU,PAM-co-OVPOSS/PU复合水凝胶对Pb2+的吸附主要是化学吸附为主结果表明两种凝胶均具有很好的吸附性能,PAM/PU [15%%(质量分数)PAM,40g/L PU]复合水凝胶最大吸附量为228mg/L,PAM-co-OVPOSS/PU [20%(质量分数)PAM-co-OVPOSS,60g/L PU]复合水凝胶最大吸附量为195mg/L。PAM-co-OVPOSS/PU比PAM/PU凝胶呈现更好的力学强度,通过实验研究、吸附动力学和吸附热力学理论模拟分析,详细讨论了凝胶对Pb2+的吸附机理和PAM-co-OVPOSS/PU凝胶力学性能的增强机理。     

钛柱撑蒙脱石颗粒的制备及其对镉离子的吸附

为脱除废水中镉离子,以钠基蒙脱石作基质材料,钛酸四丁酯为钛源,制备了钛柱撑蒙脱石。然后将聚乙烯醇、海藻酸钠、钛柱撑蒙脱石以一定的质量比制备钛柱撑蒙脱石颗粒,并进行颗粒的散失实验及镉离子的吸附实验,同时进行吸附等温线及吸附动力学研究。结果表明,Ti-MMT具有较大的晶面间距(d_(001)=3.43 nm)。当m(聚乙烯醇)∶m(海藻酸钠)∶m(钛柱撑蒙脱石)=0.6∶1.0∶20.0时,投加0.25 g颗粒于pH值=6的100 mg/L的镉离子废水中,在40℃下,吸附120 min,颗粒对Cd~(2+)的吸附量达到7.89 mg/g,去除率达到98.63%,且颗粒对Cd~(2+)的吸附符合Langmuir等温线模型,吸附动力学符合拟二级动力学方程。     

基于埃洛石的可降解水凝胶的制备及其吸附铜离子性能研究

以埃洛石、海藻酸钠和丙烯酸为功能单体,合成了基于埃洛石的可降解水凝胶复合材料,并用红外、扫描电镜对产物进行了表征,研究了复合材料对铜离子的静态吸附性能。结果表明,埃洛石的含量为10%时,在溶液pH=5.5,铜离子浓度为0.02mol/L,温度为30℃的条件下,其对铜离子的最大吸附容量为263.3mg/g。复合材料对铜离子的吸附符合准二级吸附动力学方程和朗格缪尔吸附等温线方程,对吸附热力学的研究结果表明:该复合材料对铜离子的吸附为放热过程,且是自发行为。     

Adsorption of Cd(II) and Cu(II) from aqueous solution by carbonate hydroxylapatite derived from eggshell waste

Carbonate hydroxylapatite (CHAP) synthesized by using eggshell waste as raw material has been investigated as metal adsorption for Cd(II) and Cu(II) from aqueous solutions. The effect of various parameters on adsorption process such as contact time, solution pH, amount of CHAP and initial concentration of metal ions was studied at room temperature to optimize the conditions for maximum adsorption. The results showed that the removal efficiency of Cd(II) and Cu(II) by CHAP could reach 94 and 93.17%, respectively, when the initial Cd(II) concentration 80 mg/L and Cu(II) 60 mg/L and the liquid/solid ratio was 2.5 g/L. The equilibrium sorption data for single metal systems at room temperature could be described by the Langmuir and Freundlich isotherm models. The highest value of Langmuir maximum uptake, (b), was found for cadmium (111.1mg/g) and copper (142.86 mg/g). Similar Freundlich empirical constants, K, were obtained for cadmium (2.224) and copper (7.925). Ion exchange and surface adsorption might be involved in the adsorption process of cadmium and copper. Desorption experiments showed that CaCl2, NaCl, acetic acid and ultrasonic were not efficient enough to desorb substantial amount of metal ions from the CHAP. The results obtained show that CHAP has a high affinity to cadmium and copper.     

多功能壳聚糖水凝胶医用材料的功能性研究

作为一类兼具应用价值和经济效益的新型功能高分子材料,水凝胶越来越受关注。以天然可降解的壳聚糖为载体,通过自由基接枝共聚法制备了壳聚糖水凝胶,重点研究了其吸附性及药物控释性能。结果表明:该水凝胶20d左右可以完全降解,降解性能良好。在25℃条件下,铜离子浓度为1200mg/L时,壳聚糖水凝胶对铜离子的平衡吸附量可达225.8mg/g。以亚甲基蓝为药物模型的控释实验结果表明,温度以及初始药物投加量对控释性能影响较大,48h累积释放率达70%左右,可在一定程度上实现缓释控释效果。     

纳米二氧化锰@还原氧化石墨烯对水中Pb(Ⅱ)的吸附性能与吸附机制研究

以重金属Pb(Ⅱ)为目标污染物,制备了MnO₂@还原氧化石墨烯(MnO₂@RGO)复合吸附剂。考察了吸附剂投加量、溶液pH、初始浓度和反应温度等因素对Pb(Ⅱ)去除效果的影响。结果表明:MnO₂@RGO对废水中的Pb(Ⅱ)吸附效果显著,在Pb(Ⅱ)浓度50mg/L,MnO₂@RGO投加量0.15g/L,pH为6.0,吸附时间3h的条件下,吸附量可达到124.3mg/g,Pb(Ⅱ)去除率可达到75%。纳米MnO₂@RGO可用Langmiur等温模型和伪二级动力学方程来描述,为单分子层吸附,以化学吸附为主。在MnO₂@RGO吸附剂的X射线衍射图谱中出现了MnO₂的特征吸收峰,其附着于RGO表面,印证了MnO₂@RGO吸附剂的成功制备。     

The adsorption of Cd(II) ions on sulphuric acid-treated wheat bran

The adsorption of Cd(II) ions which is one of the most important toxic metals by using sulphuric acid-treated wheat bran (STWB) was investigated. The effects of solution pH and temperature, contact time and initial Cd(II) concentration on the adsorption yield were studied. The equilibrium time for the adsorption process was determined as 4 h. The adsorbent used in this study gave the highest adsorption capacity at around pH 5.4. At this pH, adsorption capacity for an initial Cd(II) ions concentration of 100 mg/L was found to be 43.1 mg/g at 25 degrees C for contact time of 4 h. The equilibrium data were analysed using Langmuir and Freundlich isotherm models to calculate isotherm constants. The maximum adsorption capacity (qmax) which is a Langmuir constant decreased from 101.0 to 62.5 mg/g with increasing temperature from 25 to 70 degrees C. Langmuir isotherm data were evaluated to determine the thermodynamic parameters for the adsorption process. The enthalpy change (deltaH(o)) for the process was found to be exothermic. The free energy change (deltaG(o)) showed that the process was feasible. The kinetic results indicated that the adsorption process of Cd(II) ions by STWB followed first-order rate expression and adsorption rate constant was calculated as 0.0081 l/min at 25 degrees C. It was observed that the desorption yield of Cd(II) was highly pH dependent.     

Removal of trace Cd(II) from water with the manganese oxides/ACF composite electrode

The Manganese oxide/active carbon fiber (MO/ACF) was prepared and its electrosorptive properties of Cd(II) in aqueous solution were investigated. The structure of MO/ACF was characterized with transmission electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. Furthermore, the Cd(II) electrosorptive properties of MO/ACF electrodes with different bias potentials, ionic strengths, and loaded amount of manganese oxides were measured and the electrosorption isotherm and kinetics were investigated. The Cd(II) electrosorptive capacity of MO/ACF was 6 times higher than that of pure ACF. The optimal adsorptive bias voltage was 1.5 V and the optimal electrolyte concentration of NaCl was 0.1 mol/L. The adsorption isotherm was agreed well with the Freundlich adsorption model and its maximum electrosorption capacity was 14.88 mg/g by Langmuir model. The higher adsorptive capacity of MO/ACF than that of pure ACF is attributed to higher capacitance and more adsorptive sites of MO/ACF.     

The effect of some operating variables on the adsorption of lead and cadmium ions on kaolinite clay

Modification of kaolinite clay mineral with orthophosphate (p-modified sample) enhanced adsorption of Pb and Cd ions from aqueous solutions of the metal ions. Increasing pH of solutions of metal ions, increasing adsorbent dose and increasing concentration of metal ion, increased the adsorption of metal ions. Adsorption of both metal ions simultaneously on both unmodified and p-modified samples indicates that adsorption of one metal ion is suppressed to some degree by the other. The presence of electrolyte and their increasing concentration reduced the adsorption capacities of both unmodified and p-modified samples for the metal ions. Ca-electrolytes had more negative effect on the adsorption capacities of the adsorbents than Na-electrolytes. Ca-electrolytes reduced adsorption capacities of the adsorbents for Pb and Cd ions. From Langmuir plots it was observed that these electrolytes increased the binding energy constant of the metal ions unto the adsorbents especially on the p-modified samples. The rate of adsorption of Pb and Cd ions on p-modified adsorbent were increased and equilibrium of metal ion solution were more quickly reached (8min for Pb ions and 12min for Cd ions) with p-modified adsorbent as against 20min for adsorption of both metal ions on unmodified adsorbent when 200mg/L of metal ion solutions were used during the kinetic studies. When adsorption data were fitted against Langmuir, Freundlich, Toth and Langmuir-Freundlich isotherms, satisfactory fits were found with the Freundlich isotherm. However, at low concentration of metal ions, data also showed satisfactory fits to Langmuir isotherm.     

Facile preparation of magnetic sodium alginate/carboxymethyl cellulose composite hydrogel for removal of heavy metal ions from aqueous solution

A novel magnetic polysaccharide composite hydrogel was successfully constructed by using sodium alginate (SA) and carboxymethyl cellulose (CMC) as the backbone and filled with in situ Fe₃O₄ nanoparticles, which was then employed for removal of heavy metal ion from aqueous solution. The obtained magnetic SA/CMC composite hydrogel was characterized by Fourier transform infrared spectroscopy, fluorescence microscope, thermogravimetric and vibrating sample magnetometer. Effect of contact time, pH and adsorbent dosage on the adsorption of heavy metal ions by the magnetic SA/CMC hydrogel have also been studied. The results show that the prepared magnetic SA/CMC hydrogel can be effectively utilized in the removal of heavy metal ions from aqueous solution. The maximal adsorption capacity of Mn(II), Pb(II), and Cu(II) as calculated from the Langmuir model were 71.83, 89.49, and 105.93 mg/g, respectively. The adsorption process of the magnetic SA/CMC hydrogel on the heavy metal ions can be attributed to ion exchange and chemical adsorption. What’s more, the magnetic hydrogel exhibited high efficiency after four cycles, which indicating it offers great potential for practical application in the removal of heavy metal ions from aqueous solution.