Enhanced swelling and methylene blue adsorption of polyacrylamide‐based superabsorbents using alginate modified montmorillonite

Polyacrylamide/sodium alginate modified montmorillonite (PAM/SA‐MMT) superabsorbent composites were synthesized by free‐radical polymerization under normal atmospheric conditions. They were characterized by X‐ray diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy (FTIR). Their water absorbency and methylene blue (MB) adsorption behaviors were studied. Compared with PAM/MMT composites, PAM/SA‐MMT composites demonstrated greater water absorbency (863 g g^?1 in distilled water and 101 g g^?1 in 0.9 wt % NaCl solution) and higher adsorption capacity of 2639 mg g^?1 for MB. The adsorption behaviors of the composites showed that the isotherms and adsorption kinetics were in good agreement with the Langmuir equation and pseudo‐second‐order equation, respectively. FTIR analysis suggested that the MB adsorption of PAM/SA‐MMT composites via a mechanism combined electrostatic, H‐bonding and hydrophobic interaction. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014 , 131, 40013.     

Preparation of a hydroxyethyl–titanium dioxide–carboxymethyl cellulose hydrogel cage and its effect on the removal of methylene blue

A novel TiO₂ hydrogel cage model was built for the removal of methylene blue (MB), an organic pollutant. This TiO₂ hydrogel cage was prepared with the biomass materials of hydroxyethyl cellulose (HEC) and carboxymethyl cellulose (CMC), and this hydrogel cage structure was characterized by scanning electron microscopy, transmission electron microscopy, and X‐ray diffraction. The contents of the encased TiO₂ and its swelling properties with different CMC proportions of this hydrogel cage were studied to obtain a suitable crosslinking network structure and optimal synthesis conditions. Compared to an equivalent amount of pure TiO₂, the much higher removal efficiency of MB with our prepared TiO₂ hydrogel cage was attributed to the synergistic effect of the photocatalytic degradation for TiO₂ and the adsorption enrichment for cellulose hydrogels. Furthermore, the adsorption kinetics of the intraparticle diffusion model were used to study the adsorption enrichment process of the TiO₂ hydrogel cage. In addition, on the basis of the results of photocatalytic degradation and recycling experiments, excellent performances with respect to self‐cleaning, regenerative ability, and easy recovery, were shown for this HEC–TiO₂–CMC cage material, which demonstrated ideal application potential for MB removal. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44925.     

Adsorption of methylene blue on hemicellulose‐based stimuli‐responsive porous hydrogel

A stimuli‐responsive porous hydrogel was synthesized from wheat straw hemicellulose using CaCO₃ as the porogen, and its application for the removal of methylene blue was studied. The porous structure of the prepared hydrogel was confirmed by SEM analysis. The effects of pH and polyelectrolyte on the swelling of the hydrogels were discussed, and the porous hydrogels showed excellent sensitivity to pH and salt. The deswelling kinetic study indicated that the hydrogels exhibited rapid shrinking in NaCl aqueous solutions. The methylene blue adsorption on the hydrogels was investigated, and the obtained adsorption data was fitted to the pseudo‐first‐order, pseudo‐second‐order and intra‐particle diffusion kinetics models, and the pseudo‐first‐order kinetic model could describe the adsorption process, and the adsorption process of methylene blue on the hydrogels was controlled by external film diffusion. This study reported that the hemicellulose‐based porous hydrogel is promising for water treatment. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41606.     

Robust polymeric hydrogel using rod‐like amidodiol as crosslinker: Studies on adsorption kinetics and mechanism using dyes as adsorbate

Herein, we report the preparation of robust polyacrylic acid hydrogel using rod‐like amidodiol as physical crosslinker. Polyacrylic acid–amidodiol hydrogels were characterized for its chemical structure, rheology, swelling, diffusion, and adsorption properties. Kinetics and mechanism of adsorption were investigated by UV–visible spectroscopy using dyes such as rhodamine 6G and methylene blue as adsorbate. Results suggested pseudo second‐order kinetics of multilayer adsorption and hydrogel could retain its shape even after swelling. Effect of amidodiol on the adsorption of dyes was investigated. Extent of interaction between adsorbate–adsorbate and adsorbent–adsorbate was studied using Gile's model. The generated results may provide a low cost simple technology for developing robust polymeric hydrogel adsorbent. The adsorption characteristics results can be exploited for setting up pilot plant adsorbent for the removal of such organic toxic materials. Finally, we have demonstrated its application for the removal of dyes from waste water collected from textile and paper industries. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40908.     

Simultaneous adsorptive removal of methylene blue and copper ions from aqueous solution by ferrocene‐modified cation exchange resin

Resin was modified with ferrocene (Fc) to enhance removal of Methylene Blue (MB) and Cu²⁺ from simulated wastewater. The FTIR, N₂‐BET, and X‐ray fluorescence analysis confirmed that Fc was successfully grafted onto the surface of resin. The adsorption capacity of Fc modified cation exchange resin (FMCER) was calculated to be 392.16 mg/g Cu²⁺ and 10.01 mg/g MB. Both processes were spontaneous and exothermic, best described by Langmuir equation. Pseudo‐first‐order kinetic model satisfied the adsorption of MB, while the intraparticle‐diffusion model fitted the kinetics of Cu²⁺ adsorption best. The result revealed a multilayer adsorption of Cu²⁺ on FMCER, and the kinetics maybe controlled by intraparticle diffusion, film diffusion, and competition force. The adsorption of MB and Cu²⁺ on FMCER were physicosorptive, with activation energies of 2.09 and 1.27 kJ/mol. pH 2–7 and 4–5 are optimum for the removal of MB and Cu²⁺, and pH 4 is optimal for the simultaneous removal of MB and Cu²⁺. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41029.     

Treatment of pollutants in wastewater: Adsorption of methylene blue onto olive-based activated carbon

This study used olive stone-based activated carbon for the removal of methylene blue from wastewater in order to evaluate the adsorption capacity of the carbon. The equilibrium and kinetics of adsorption were examined at 25°, 30°, 35° and 40 °C and several agitation speeds. Type III adsorption isotherms corresponding to physical adsorption in a multilayer system were used for the methylene blue system. The equilibrium data for methylene blue adsorption showed a good fit to the Freundlich equation. The kinetic data was analysed to determine kinetic constants and order of reaction. Kinetics was evaluated by means of an n-order model, showing that the reaction was a first-order reaction. The results indicated that olive stone-based activated carbon could be used as a low-cost alternative to commercial activated carbon for the removal of organic compounds from wastewater. However, due to its microporosity, the application of this type of activated carbon was found to be suitable for molecules smaller than methylene blue.     

Carboxymethyl sago pulp/carboxymethyl sago starch hydrogel: Effect of polymer mixing ratio and study of controlled drug release

Carboxymethyl sag o pulp (CMSP)/carboxymethyl sago starch (CMSS) hydrogel was synthesized by electron beam irradiation. In the series of hydrogels prepared, 40%/20% CMSP/CMSS hydrogel had the highest gel fraction. The swelling capacity of CMSP/CMSS hydrogel was found to be highest in distilled water, followed by pH 11, pH 7.4, and pH 1.2. Scanning Electron Microscope photographs revealed that the drug‐loaded hydrogel had a smoother surface than unloaded hydrogel. Fourier Transform Infrared and Differential Scanning Calorimetry analysis showed the absence of interaction between the hydrogels and the drug. All drug‐loaded hydrogels had drug encapsulation efficiency between 63% and 69%. CMSP/CMSS hydrogel swelled and allowed the release of drug at pH 7.4. These properties qualify the hydrogel as a potential candidate for controlled drug release at the ocular and colonic regions. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43652.     

Preparation of carboxymethyl sago pulp hydrogel from sago waste by electron beam irradiation and swelling behavior in water and various pH media

Solutions of carboxymethyl sago pulp (CMSP) of various degree of substitution were irradiated with electron beam of various radiation doses. The gelation dose (D_g) and p_o/q_o ratio (p_o is degradation density, q_o is crosslinking density) is dependent on CMSP concentration and degree of substitution. In the range of concentrations of 10% to 80% (w/v) CMSP with degree of substitutions of 0.4, 0.6, and 0.8, the p_o/q_o ratio decreases with increasing %CMSP showing that crosslinking processes are dominating and increasing the gel network of the CMSP hydrogel. The fourier transform infrared spectra of CMSP hydrogels of degree of substitutions of 0.4, 0.6, and 0.8 with percentage of gel fractions 25, 35, and ≥ 40 show differences in the intensity of the absorption bands at 1020–1100, 1326, and 1422 cm^?1 with different degree of substitutions and percentage of gel fraction (%GF) that correspond to different extents of chain scission and crosslinking. The swelling behavior in water shows that CMSP hydrogels could absorb 3500–5300% of water by 1 g of CMSP hydrogel. The ability to absorb water increases with the decrease of degree of substitution and %GF of the CMSP hydrogels. It is also observed that the optimum pH for swelling CMSP hydrogel is at pH 7. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2013     

Adsorption of disperse dye by powdered activated carbon

The purpose of this laboratory study is to investigate the effectiveness of powered activated carbon (PAC) on the removal of chemical oxygen demand (COD) and color of disperse dye and the effect of PAC particle size on the treatment efficiency. The adsorption isotherm parameters for the Langmuir, Freundlich and BET model are determined using the adsorption data. It has been found that the multilayer BET isotherm yields significantly better fit to the observed data than the monolayer ones. A simplified mass transfer model is proposed in the present work also for estimating the external mass transfer coefficient using the initial adsorption data at low PAC dosage.     

Absorption characterization of Ca2+, Na+, and K+ on irradiation crosslinked carboxymethyl sago pulp hydrogel

Hydrogel of carboxymethyl sago pulp (CMSP) of various degree of substitution (DS) was prepared by electron beam irradiation of various radiation doses. The CMSP hydrogels were subjected to swelling in different ionic strength solutions of KCl, NaCl, and CaCl₂. The CMSP hydrogels, due to its polyelectrolyte nature, were found to be highly sensitive to ionic strength of the medium. All the CMSP hydrogels showed the absorption of K⁺ and Ca²⁺ increases with the increase in the concentrations of the respective cation solutions. The cation absorption also decreases with DS and % gel fraction (%GF) of the CMSP hydrogels. Subjecting the CMSP hydrogels in NaCl results in deswelling and releases Na⁺ to swelling medium where the Na⁺ release increases with the increase of DS and %GF. The sorption capacity depends on the extent of crosslinking and decreases with the increase in the extent of crosslinking. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

活性炭对水中亚甲基蓝的吸附性能研究

以活性炭为吸附剂,亚甲基蓝(MB)为吸附质,考察了吸附剂用量、吸附时间、温度对活性炭去除亚甲基蓝的影响。分别采用伪一级、伪二级动力学模型和Langmuir,Freundlich吸附等温线模型对吸附动力学和等温线进行分析。实验表明,在活性炭用量为0.667 g/L,吸附时间为360 min,反应温度为298 K时,活性炭对亚甲基蓝的最大吸附量为249.081 mg/g。吸附反应在前30 min内速率很快,并约在360 min内达到吸附平衡,吸附动力学符合伪二级动力学模型。吸附反应为放热反应,等温吸附过程符合Langmuir和Freundlich吸附等温模型,相关系数高于0.99。活性炭对去除水中亚甲基蓝效果好,是一种优良的吸附剂。     

壳聚糖质活性炭对亚甲基蓝的吸附性能研究

用壳聚糖制成活性炭,研究其对亚甲基蓝的吸附能力,并分析了吸附动力学以及吸附等温线。结果显示,壳聚糖质活性炭对亚甲基蓝最佳的吸附条件为:投入量为0.3 g,吸附时间为60 min,亚甲基蓝体积为10 mL;吸附温度为50℃,吸附过程较为符合二级吸附动力学方程、Freundlich模型。     

Highly effective adsorption performance of carboxymethyl cellulose microspheres crosslinked with epichlorohydrin

Different sizes of epichlorohydrin‐crosslinked carboxymethyl cellulose (E/CMC) microspheres were successfully prepared by an inverse suspension method. With further modification by monochloroacetic acid (MCA), MCA–E/CMC microspheres were successfully synthesized. The structures and morphologies of these microspheres were analyzed with polarizing microscopy, scanning electron microscopy, ultraviolet–visible spectroscopy, Fourier transform infrared spectroscopy, Brunauer–Emmett–Teller analysis, and laser particle ζ‐potential recording. The adsorption properties of the microspheres were investigated with methylene blue (MB) as a model pollutant. The highest adsorption amount of MB (998.2 mg/g) onto MCA–E_0.7/CMC which was the samples which treated with 0.7 mL of C₄H₉OH was obtained. Meanwhile, the effect of the operating parameters, such as the contact time, initial pH of the solution, temperature, and initial dye concentration, on the adsorption amount and MB removal were systematically studied. The results show that pseudo‐second‐order kinetic model provided the best correlation with the experimental data for the adsorption of MB onto the MCA–E_0.7/CMC microspheres. Both the physical and chemical adsorption played the main role in the adsorption process. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44363.     

Removal of Basic Blue 3 by sorption onto a weak acid acrylic resin

A weak acid acrylic resin was used as an adsorbent for the investigation of Basic Blue 3 (BB3) adsorption kinetics, isotherms, and thermodynamic parameters. Batch adsorption studies were carried out to evaluate the effect of pH, contact time, initial concentration (28–100 mg/g), adsorbent dose (0.05–0.3 g), and temperature (290–323 K) on the removal of BB3. The adsorption equilibrium data were analyzed by the Langmuir, Temkin, and Freundlich isotherm models, with the best fitting being the first one. The adsorption capacity (Q_o) increased with increasing initial dye concentration, adsorbent dose, and temperature; the highest maximum Q_o (59.53 mg/g) was obtained at 323 K. Pseudo‐first‐order and pseudo‐second‐order kinetic models and intraparticle diffusion models were used to analyze the kinetic data; good agreement between the experimental and calculated amounts of dye adsorbed at equilibrium were obtained for the pseudo‐second‐order kinetic models for the entire investigated concentrations domain. Various thermodynamic parameters, such as standard enthalpy of adsorption (ΔH^o = 88.817 kJ/mol), standard entropy of adsorption (ΔS^o = 0.307 kJ mol^?1 K^?1), and Gibbs free energy (ΔG^o < 0, for all temperatures investigated), were evaluated and revealed that the adsorption process was endothermic and favorable. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis of calix[6]arene based XAD‐4 material for the removal of reactive blue 19 from aqueous environments

This study describes the synthesis of calix[6]arene (C6) appended Amberlite XAD‐4 resin and its application for the removal of anthraquinone‐based reactive blue 19 (RB‐19) dye from aqueous environments. The C6‐resin 5 was characterized with various analytical techniques, including Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, and elemental analysis. Adsorption experiments were carried out to investigate the effects of the pH, adsorbent dosage, electrolyte, contact time, and temperature on the adsorption of RB‐19 dye onto the C6‐resin 5. From the results, we observed that the percentage adsorption of the RB‐19 dye was highly dependent on the concentration of electrolyte and the pH of the solution. The maximum adsorption was achieved at pH 9. The thermal study demonstrated that the adsorption process was endothermic and spontaneous in nature. The isothermic study showed that the adsorption behavior could be better demonstrated by the Langmuir and Dubinin and Radushkevich isotherm model. From field studies, it has been concluded that C6‐resin 5 is an effective adsorbent for the removal of RB‐19 dye. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 776‐785, 2013     

Dual crosslinked carboxymethyl sago pulp/pectin hydrogel beads as potential carrier for colon‐targeted drug delivery

Carboxymethyl sago pulp (CMSP)/pectin hydrogel beads were synthesized by calcium crosslinking and further crosslinked by electron beam irradiation to form drug carrier for colon‐targeted drug. Sphere‐shaped CMSP/pectin 15%/5% hydrogel beads is able to stay intact for 24 h in swelling medium at pH 7.4. It shows pH‐sensitive behavior as the swelling degree increases as pH increases. Fourier transform infrared spectroscopy analysis confirmed the absence of chemical interaction between hydrogel beads and diclofenac sodium. Differential scanning calorimetric and X‐ray diffraction studies indicate the amorphous nature of entrapped diclofenac sodium. The drug encapsulation efficiency is up to about 50%. Less than 9% of drug has been released at pH 1.2 and the hydrogel beads sustain the drug release at pH 7.4 over 30 h. This shows the potential of CMSP/pectin hydrogel beads as carrier for colon‐targeted drug. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43416.     

Adsorption of trivalent chromium from aqueous solutions onto activated carbon

The adsorption of chromium (III) onto activated carbon was investigated as a possible alternative method for its removal from aqueous solutions. The adsorption data were obtained in a batch adsorber and fitted the Langmuir adsorption isotherm well. The effect of pH on the adsorption isotherm was investigated at pH values of 2, 4, 5 and 6. It was found that at pH values below 2 the Cr(III) was not adsorbed and at pH values above 6.4 the Cr(III) was precipitated as Cr(OH)₃. Maximum adsorption occurred at pH 5. The pH plays a very important role in the adsorption of Cr(III) since Cr(III) can form different complexes in aqueous solutions. The adsorption capacity was increased by about 20% as the temperature was raised from 25 to 40°C. It was concluded that Cr(III) is adsorbed to an appreciable extent on activated carbon and that the adsorption is highly dependent upon pH.     

Effects of a pretreatment with N‐methylmorpholine‐N‐oxide on the structures and properties of ramie

To improve the dyeing properties of ramie, the ecofriendly organic solvent N‐methylmorpholine‐N‐oxide (NMMO) was used to substitute sodium hydroxide as a ramie‐fiber swelling solvent. Through padding and baking pretreatment, ramie fabric was modified by an NMMO aqueous solution. Ultraviolet–visible spectrophotometry, Fourier transform infrared spectroscopy, X‐ray diffraction, and differential scanning calorimetry were used to investigate the effects of NMMO pretreatment on the structure of the ramie, whereas the color strength (K/S, where K is the light absorption coefficient and S is the scattering coefficient), adsorption isotherm, and dye uptake rate curve were measured to investigate the effects of NMMO pretreatment on the dyeing properties of the ramie. The results show that the ramie fiber experienced a limited and irreversible swelling because of the partial breakage of interhydrogen and intrahydrogen bonds of cellulose molecules in the amorphous area, but the crystal and chemical structure of the ramie fiber did not change obviously under the experimental conditions. The K/S value of the NMMO‐modified ramie fabrics dyed with reactive dyes increased by about 100%, and the dye uptake increased by 27.88% compared to that of the raw sample, whereas the standard affinity and diffusion coefficient value of the reactive dyes on the NMMO‐modified ramie fabric were higher than those of the raw ramie fabric. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

粉末活性炭静态吸附水中硝基酚的试验研究

研究了常温(20℃)条件下粉末活性炭(PAC)对水中3-硝基酚、4-硝基酚、2,6-二硝基酚和2,4-二硝基酚4种硝基酚的静态吸附规律;并对照研究了未驯化的灭活活性污泥存在时,PAC对硝基酚的吸附性能。结果表明:PAC对4种硝基酚的吸附能力远大于灭活活性污泥;当硝基酚与PAC的质量比值在0.2~1.0时,PAC对4种硝基酚的吸附在60 min内可达到平衡,且均符合Langmiur吸附模型;用Langmiur吸附模型对试验数据进行拟合,得出了PAC对4种硝基酚的饱和吸附容量和吸附系数。