腐植酸钠/聚N-异丙基丙烯酰胺/粘土杂化水凝胶的合成及脱色性能

以N-异丙基丙烯酰胺单体、粘土和腐植酸钠为原料合成了温敏腐植酸钠/聚N-异丙基丙烯酰胺/粘土（SH/PNIPA/clay）系列水凝胶。用红外光谱分析仪对其内部相互作用进行了研究,并用紫外可见分光光度计对水凝胶吸附-解吸亚甲基蓝的性能进行了测试。实验结果表明凝胶中SH与PNIPA形成了氢键;凝胶对亚甲基蓝（MB）的吸附和解吸能力受腐植酸钠的含量、粘土含量、亚甲基蓝的起始浓度和温度的影响。２％粘土含量和低温条件有利于凝胶吸附和解吸。     

ABSORPTION OF METAL IONS AND SWELLING PROPERTIES OF POLY(ACRYLIC ACID-CO-ITACONIC ACID) HYDROGELS

Hydrogels of acrylic acid and itaconic acid has been synthesized with different monomers ratios. The swelling process of the different xerogels immersed in water and salt solutions has been studied. The swelling of hydrogels loaded with metal cations (Cu²⁺, Zn²⁺) was also investigated. The swelling process was monitored by the increase in the weight of hydrogel as a function of time. The absorption properties of metal ions were studied by using the hydrogel, and different concentrations of copper and zinc solutions (prepared from sulphate salts). The influence of pH on the absorption process was studied. For the absorption of metal ions, the amount of ions absorbed within the hydrogel can be calculated from the initial and equilibrium concentrations of the metal ions in aqueous phase, the weight of the hydrogel, and the volume of solution used. Metal absorption increased when pH, salt concentration in external solution and itaconic acid content is levelled.

The swelling isotherms which consisted of an initial fast increase levelled off asymptotically to the equilibrium swelling limit. The experimental data clearly suggest that our hydrogels follow a second-order kinetics for both cases (unload and metal loaded). The kinetics rate constant and the equilibrium water content, K, have been calculated for every monomer ratio from the experimental data according to the kinetics equation. Both magnitudes decreased as the itaconic acid content decreases in the xerogels.     

Removal of methylene blue from aqueous solution by graphene oxide

Graphene oxide (GO) is a highly effective absorbent of methylene blue (MB) and can be used to remove MB from aqueous solution. A huge absorption capacity of 714 mg/g is observed. At initial MB concentrations lower than 250 mg/L, the removal efficiency is higher than 99% and the solution can be decolorized to nearly colorless. The removal process is fast and more efficient at lower temperatures and higher pH values. The increase of ionic strength and the presence of dissolved organic matter would further enhance the removal process when MB concentration is high. The results indicate that GO can be applied in treating industrial effluent and contaminated natural water. The implications to graphene-based environmental technologies are discussed.     

辐射交联制备改性CMC水凝胶的溶胀行为研究

利用丙烯酰胺 (AAm)接枝改性纤维素 ,然后进行羧甲基化反应得到高取代度的丙烯酰胺 羧甲基纤维素钠 (AAm CMC Na) .对该材料进行γ射线辐照制备出新型改性CMC水凝胶 .研究了这种水凝胶的溶胀动力学、交联动力学以及温度、pH值和无机盐浓度对水凝胶溶胀行为的影响 ,并与CMC Na水凝胶进行了比较 .结果表明 ,该水凝胶和CMC Na水凝胶相比 ,优点在于辐照交联所用的剂量下降 ,而且所需的CMC浓度减少 .AAm CMC Na水凝胶的溶胀度随温度升高而增大 ,在pH为 6～ 8范围内达到最大值 ,并随无机盐浓度与吸收剂量增加而下降 ,表现出较好的温度敏感性和pH敏感性 ,可望作为吸水材料和水保持剂     

Preparation and characterization of novel bi-functionalized xerogel for removal of methylene blue and lead ions from aqueous solution in batch and fixed-bed modes: RSM optimization,kinetic and equilibrium studies

A new bi-functionalized xerogel is fabricated and then was identified by ²⁹Si CP MAS NMR, SEM, FTIR, and nitrogen adsorption–desorption approaches. As-prepared xerogel efficiency for simultaneous uptake of methylene blue (MB) and Pb²⁺ ions from aqueous solution is investigated. Individual and combination effects of operating variables (xerogel mass, contact time and initial MB and Pb²⁺ ion concentration) on the retention performance is achieved with central composite design (CCD) and upgraded through response surface method (RSM). Batch equilibrium outcomes uncovered that MB and Pb²⁺ ions adsorption onto hybrid composite could be all around depicted by Langmuir isotherm model contrasted with Freundlich equation. Howbeit, the column trials reported that the breakthrough capacities of MB and Pb(II) are observed to be 512 mg.g⁻¹ and 400 mg.g⁻¹ respectively. XPS and FTIR investigations uncovered that the main mechanism of lead uptake ought to be credited to the chelation with –NH₂ and ion exchange with –SH groups in the xerogel frameworks. While the MB adsorption system is proposed to be electrostatic attractions, π-π stacking interactions and hydrogen bonds. The work undertaken in this research highlights the major role of the as-synthesized xerogel for treatment of industrial wastewater.     

Decontamination of methylene blue from aqueous media using alginate-bonded polyacrylamide/carbon black nanocomposite hydrogel

This work synthesized the novel alginate (Alg) based nanocomposite hydrogel using the free radical polymerization method to remove methylene blue (MB) from the aqueous solution. The successful grafting of acrylamide (AAm) monomer onto the alginate backbone was confirmed by the FTIR test. Different carbon black (CB) nanoparticle levels (0–12.5 wt.%) were embedded in a hydrogel matrix to enhance the removal efficiency, and its optimum value was obtained at 7.5 wt.%. FTIR, TGA, BET, and SEM analyses were performed to characterize synthesized adsorbents. TGA results showed that Alg-g-poly(AAm)/CB nanocomposite hydrogel has a higher thermal stability than Alg-g-poly(AAm) hydrogel. SEM analysis showed that incorporating CB into Alg-g-poly(AAm) considerably enhances roughness and surface area. Also, a higher surface area of Alg-g-poly(AAm)/CB (2.5 m²/g) was confirmed by BET analysis. The removal efficiency of nanocomposite hydrogel at optimum conditions of pH 6, initial concentration 10 mg/L, temperature 25 °C, and contact time 60 min was calculated at 94.63%. The kinetic and isotherm data were best fitted to pseudo-second-order and Langmuir models. The monolayer adsorption capacity for Alg-g-poly(AAm) and Alg-g-poly(AAm)/CB were calculated at 22.77 and 24.56 mg/g, respectively, showing CB's effectiveness in improving MB adsorption. The thermodynamic study showed that the removal process of MB by both adsorbents is spontaneous and exothermic, and entropy decreases. The synthesized adsorbents showed a good performance in textile wastewater treatment. Finally, it can be concluded that the synthesized adsorbents can be successfully applied for wastewater treatment application.     

Hydrogel containing L-valine residues as a platform for cisplatin chemotherapy

Two acrylic hydrogels, of low cross-linking content and carrying the L-valine residues, were synthesized and studied as a platform to load and release the chemotherapeutic agent cisplatin. The platinum(II)-complex species showed a well-defined stoichiometric ratio in which two carboxylate groups of the collapsing gel coordinate a metal center; this was confirmed by FT-IR spectra. When loaded in water, a zero-order release rate of platinum(II)-species was shown in the physiologic solution (PBS, pH 7.40) for more than one week. Moreover, the amount of platinum(II)-species released from the hydrogel may be improved either by the cross-linking degree and by the temperature. Any increase of the cross-links results in a decreased slope of the straightline Pt(II)/gel (mg/g) versus time, whereas the increasing temperature results in a greater amount of platinum(II)-species in solution. The chemical- and swelling-controlled release are the main mechanisms supervising the whole release process. On the other hand, the loading of cisplatin and temsirolimus in DMF showed a characteristic two phase releasing pattern; the initial burst effect was always followed by the zero-order release rate for a week. In this case only a swelling-controlled mechanism was mainly invoked. The cytotoxic activity towards Me665/2/21 human melanoma cell line, afforded by the cisplatin-loaded hydrogel, was close and in some cases higher compared to the native cisplatin at the same concentration; an interesting synergy in term of cytotoxicity was observed when a combined treatment of temsirolimus and cisplatin was used, although temsirolimus exerted only a moderate inhibition of cell proliferation.     

Efficient Adsorption and Recovery of Pb(II) from Aqueous Solution by a Granular pH-Sensitive Chitosan-based Semi-IPN Hydrogel

A series of granular pH-sensitive semi-interpenetrating polymer network (semi-IPN) hydrogels based on chitosan (CTS), acrylic acid (AA) and gelatine (GE) were utilized for the adsorption and recycle of Pb(II) from aqueous solutions. The composite hydrogels have been characterized by FT-IR and TGA. The effects of contact time, pH value and initial Pb(II) concentration on the adsorption were investigated. Results indicated that the adsorption capacity of the hydrogel increased with increasing pH value and initial Pb(II) concentration, and a pH-sensitive adsorption characteristic was presented. The adsorption rate of the semi-IPN hydrogels on Pb(II) is fast with an adsorption rate constant of 14.9790 mg/(g·s), and adsorption equilibrium could be reached within 10 min. The adsorption isotherms of the hydrogels for Pb(II) could be described well by the Langmuir equation, rather than the Freundlich equation. The as-prepared hydrogels showed good reusability with 0.05 mol/l HNO₃ solutions as the desorbing agent and 0.1 mol/l NaOH solutions as the regeneration agent, respectively. After five consecutive adsorption-desorption processes, the semi-IPN hydrogel with 20 wt% GE may reach 85.26% of its initial adsorption capacity. In addition, the adsorbed Pb(II) can be quantitatively recovered by simply eluting the hydrogel with dilute HNO₃ solution, and a recovery ratio of 89.27% was reached for the semi-IPN hydrogel. The satisfactory adsorption amount is mainly derived from the chelating of functional groups (i.e. –COO^? and –NH₂) with Pb(II) ions. The hydrogel adsorbents exhibited excellent affinity for Pb(II), and can be applied to treat wastewater containing heavy metal ion and simultaneously recover the valuable metal sources.     

Water affinity and permeability in membranes of alginate-Ca2+ containing poly(n-isopropylacrylamide)

Hydrogels based on semi-interpenetrating network (semi-IPN) combining alginate-Ca²⁺ (matrix) with poly(N-isopropyl acrylamide) (PNIPAAm) were prepared and characterized in order to determine their affinity to water and their permeability to orange II as a function of temperature. Membranes of these hydrogels were obtained by gelation of the aqueous solution of alginate and PNIPAAm by the addition of CaCl₂. The presence of PNIPAAm chains inside the hydrogels alters the water affinity when compared to the pure alginate-Ca²⁺ hydrogels. Although the water uptake capability decreases above 32 °C (Low Critical Solution Temperature (LCST) of PNIPAAm in water), no shrinking of the semi-IPN hydrogels during the phase separation of the PNIPAAm was observed. The permeability of orange II as a function of temperature decreases at 32 °C and shows a dependence on the molar mass of the alginate. The partition coefficient of orange II in the hydrogel membrane, relative to water, decreases by increasing the temperature and its permeability follows a similar behavior. It was proposed that above the LCST of PNIPAAm the Alginate-Ca²⁺ networks mechanically support the collapsed PNIPAAm chains and the diffusion of orange II is minimized. The collapsing process may be followed by the formation of a complex between the carboxylic side groups of alginate and –NH–R groups of PNIPAAm. It would expose the isopropyl groups of PNIPAAm chains, providing a hydrophobic environment that minimizes the interaction between the dye and the polymeric matrix.     

Decomposition of Methylene Blue in Water by Corona Discharges

The decomposition of methylene blue (MB) in aqueous solution was investigated using a pulsed corona discharge. The discharge was ignited in the gas bubbled in the solution through several needle electrodes. The influence of treatment time, volume of the treated solution and initial concentration of the dye in solution on MB degradation was studied. The effect of the nature of the gas introduced was also investigated. For the same energy input, MB conversion increased in the order air < argon < oxygen. When using oxygen, the decomposition of MB exceeded 95% after ~20 min plasma treatment. Higher efficiency was obtained for higher treated volume and higher initial concentration. At 90% conversion the yield obtained with oxygen was ~5 g/kWh for an initial concentration of 150 mg/l and a treated volume of solution of 100 ml.     

腐植酸钠/聚丙烯酰胺/粘土杂化水凝胶的研究

以过硫酸钾为引发剂、N,N′-亚甲基双丙烯酰胺为交联剂、丙烯酰胺单体和腐植酸钠、Laponite RD粘土为原料,用溶液聚合交联法合成了腐植酸钠/聚丙烯酰胺/粘土(SH-PAM-Clay)系列水凝胶.用场发射扫描电镜对其表面形貌进行了研究,并对水凝胶的吸水性和流变性能进行了测试和研究.结果表明这系列水凝胶都具有致密的网络结构和优良的吸水性能.     

Baked hydrogel from corn starch and chitosan blends cross‐linked by citric acid: Preparation and properties

Citric acid (CA)–modified hydrogels from corn starch and chitosan were synthesized using a semidry condition. This strategy has great benefits of friendly environment because of the absence of organic solvents and compatible with the industrial process. The hydrogel blends were prepared with starch/chitosan ratios of 75/25, 50/50, and 25/75. The thermal stability, morphology, water absorption, weight loss in water, and methylene blue absorption were determined. Multi‐carboxyl structure of CA could result in a chemical cross‐linking reaction between starch, chitosan, and CA. The cross‐linking reaction between free hydroxyl groups of starch, amino groups of chitosan, and carboxyl groups of CA has been confirmed by attenuated total reflectance infrared (ATR‐IR) spectroscopy, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA) analysis. The water absorption properties of CA‐modified hydrogel blends were increased significantly compared with the native starch and chitosan. Moreover, the hydrogel blends modified with CA showed good water resistance and gel content. The morphology study confirmed the complete chemical cross‐linking and porous structure of hydrogel blends. The hydrogel blend with the starch/chitosan ratio of 50/50 presented powerful absorption of methylene blue as well as chemical cross‐linking reaction and dense structure. In sum, the hydrogel blend comprising 50% starch and 50% chitosan has the potential to be applied for water maintaining at large areas, for example, in agriculture.     

Biodegradable water absorbent synthesized from bacterial poly(amino acid)s

Biodegradable hydrogels prepared by gamma-irradiation from microbial poly(amino acid)s have been studied. pH-Sensitive hydrogels were prepared by the gamma-irradiation of poly(gamma-glutamic acid) (PGA) produced by Bacillus subtilis and poly(epsilon-lysine) (PL) produced by Streptomyces albulus in aqueous solutions. When the gamma-irradiation dose was 19 kGy or more, and the concentration of PGA in water was 2 wt.-% or more, transparent hydrogels could be produced. For the 19 kGy dose, the produced hydrogel was very weak, however, the specific water content (wt. of absorbed water/wt. of dry hydrogel) of this PGA hydrogel was approximately 3,500. The specific water content decreased to 200, increasing when the gamma-irradiation dose was over 100 kGy. Under acid conditions or upon the addition of electrolytes, the PGA hydrogels shrunk. The PGA hydrogel was pH-sensitive and the change in the volume of the hydrogel depended on the pH value outside the hydrogel in the swelling medium. This PGA hydrogel was hydrodegradable and biodegradable. A new novel purifier reagent (coagulant), made from the PGA hydrogels, for contaminated turbid water has been found and developed by Japanese companies. A very small amount of this coagulant (only 2 ppm in turbid water) with poly(aluminum chloride) can be used for the purification of turbid water. A PL aqueous solution also can change into a hydrogel by gamma-irradiation. The specific water content of the PL hydrogel ranged from 20 to 160 depending on the preparation conditions. Under acid conditions, the PL hydrogel swelled because of the ionic repulsion of the protonated amino groups in the PL molecules. The rate of enzymatic degradation of the respective PL hydrogels by a neutral protease was much faster than the rate of simple hydrolytic degradation.     

Insight into the binding of divalent cations to Sepia eumelanin from IR absorption spectroscopy

IR absorption spectroscopy is used to examine the binding of the divalent cations Mg(II), Ca(II), Zn(II) and Cu(II) to melanin granules isolated from the ink sacs of Sepia officinalis. The functional groups of the melanin granules interacting with the bound metal ions are deduced by examining the effect of metal concentration on transition frequencies associated with the COOH, NH and OH moieties of the pigment. The coordinating groups vary with metal ion and with concentration. For the experimental conditions used (initial solution pH of 4, ionic strength of 100 mM and a melanin concentration of 1 mg mL(-1)) Mg(II), Ca(II) and Zn(II) bind to carboxylate groups and Cu(II) binds predominantly to phenolic (catechol) groups However, at a concentration of 10 mM Cu(II) also shows evidence of binding to carboxylate and amine groups, reflecting a secondary binding site that becomes populated as the catechol sites are depleted.     

Pseudopeptide‐Based Hydrogels Trapping Methylene Blue and Eosin Y

We present herein the preparation of four different hydrogels based on the pseudopeptide gelator Fmoc‐l ‐Phe‐d ‐Oxd‐OH (Fmoc=fluorenylmethyloxycarbonyl), either by changing the gelator concentration or adding graphene oxide (GO) to the water solution. The hydrogels have been analysed by rheological studies that demonstrated that pure hydrogels are slightly stronger compared to GO‐loaded hydrogels. Then the hydrogels efficiency to trap the cationic methylene blue (MB) and anionic eosin Y (EY) dyes has been analyzed. MB is efficiently trapped by both the pure hydrogel and the GO‐loaded hydrogel through π–π interactions and electrostatic interactions. In contrast, the removal of the anionic EY is achieved in less satisfactory yields, due to the unfavourable electrostatic interactions between the dye, the gelator and GO.     

Needleless electrospinning of poly(acrylic acid) superabsorbent: Fabrication,characterization and swelling behavior

In this work, nanofibrous hydrogel has been fabricated from needleless electrospinning of Poly(acrylic acid) (PAA) in an aqueous solution with different concentrations. First, all solution samples were characterized for pH, surface tension, conductivity and viscosity. Next, electrospinnability of the PAA-water dope solution was investigated using the needleless electrospinning technique under constant conditions. Results indicated that the PAA-water solution was not electrospinnable. Therefore, the neutralization of carboxylic groups in the PAA chemical structure using the NaOH solution was investigated to enhance the PAA electrospinnability. Morphology observation revealed that the fiber diameters ranged from 40 to 250 nm and increased with increasing the solution concentrations. Increasing the neutralization degree (10%, 15% and 20% with 50 wt% NaOH solution) led to increase the dope viscosity and conductivity. The resultant nanofibers could be rendered water-insoluble by incorporating 1,4-butanediol diglycidyl-ether in the PAA-water dope solution, then heat-induced crosslinking was performed using a microwave at different curing times (1–5 min) and temperatures (45–105 °C). The nanofibrous hydrogel mat was then characterized by FTIR. The resulting nanofibrous hydrogel showed remarkable water absorption capacity up to 17,000% and 51,000% (within 15 min) in the standard saline solution and distilled water, respectively.     

LED-compatible copper(II)-selective optrode membrane based on lipophilized Zincon

An optical single shot test for copper(II) ion is presented. The membrane consists of a polyester support and an active layer composed of hydrogel, a hydroxylic plasticizer, and Zincon. The latter has been made lipophilic by ion-pairing with tetraoctyl-ammonium bromide. The membrane responds to copper ions in giving a color change from pink to blue. Because the layer irreversibly extracts copper from the solution, a kinetic approach has been used for quantitation, in that the membrane has been exposed to the sample for 2 min and the initial slope of the response curve has been determined. A linear calibration graph has been obtained for the 1 to 100 mol/l (63.5 g/kg to 6.35 mg/kg) copper concentration range. The complexed form of the dye exhibits an absorption maximum of 620 nm which matches the emission band of the orange light-emitting diode (LED). Measurements have been performed at pH 6, because no complexation of zinc occurs in this range. The long term stability of the membrane exceeds 6 months when stored dry and in the dark. The strong binding of copper ions along with the fairly high selectivity of the membrane also suggests its use as a preconcentration phase.Dedicated to Professor Dr. Dieter Klockow on the occasion of his 60th birthday     

磷钨酸对甲基橙光催化降解的初步研究

在自制的光化学反应器中,以紫外灯为光源,以磷钨酸为光催化剂,研究了其对模拟甲基橙染料废水的光催化脱色降解的影响。实验结果表明,催化剂加入量、溶液初始浓度、不同光强度是影响催化降解效果的重要因素。最佳催化条件为20 mg/L的甲基橙溶液在紫外灯(16W)辐射下,光催化剂磷钨酸用量为1.5 g/L。     

Fe-Ni 共掺杂 ZnO 的制备及其光催化降解甲基橙活性

 采用溶液法制备了 Fe-Ni 共掺杂 ZnO 光催化剂, 并运用 X 射线衍射、扫描电镜和原子发射光谱等对催化剂进行了表征. 以甲基橙 (MO) 为模型污染物, 评价了样品的光催化活性, 考察了甲基橙初始浓度及其 pH 值, 以及催化剂用量等对光催化反应性能的影响. 结果表明, Fe-Ni 共掺杂降低了 ZnO 的结晶度, 并促进了晶粒的长大. 光催化降解反应表明, Fe-Ni 共掺杂显著提高了 ZnO 光催化降解甲基橙的活性, 当催化剂用量为 0.6 g/L, 经 120 min 紫外光照射时, 可使甲基橙溶液 (10 mg/L) 降解率达到 93.5%. 关键词：铁; 镍; 共掺杂; 氧化锌; 光催化; 甲基橙; 降解