Dangge Gao

Adsorptive removal of vinyl polymer tanning agents from aqueous solution using wastewater activated sludge

AbstractAdsorptive studies were carried out on four synthetic vinyl polymer tanning agents removal from aqueous phase onto wastewater activated sludge (AS). Batch experiments investigated the effects of contact time, dosage of adsorbate, extracellular polymeric substances (EPS), coexisted cations, and physical property of sludge flocs on the four vinyl polymers removal by AS to evaluate the kinetics, isotherms, and mechanisms. Almost 96% of polydiallyldimethylammonium chloride-acrylic-acrylamide (PDM-AA-AM), 90% of polydiallyldimethylammonium chloride-acrylic (PDM-AA), 82% of polydiallyldimethylammonium chloride-acrylic-acrylamide-hydroxyethyl acrylate (PDM-AA-AM-HEA), and 56% of polydiallyldimethylammonium chloride (PDM) were removed from aqueous solutions. The kinetics process of adsorption can be described by the pseudo-second-order kinetic equation and the adsorption isotherms fitted to the Langmuir model very well. The adsorption capacity increases with the increase in initial vinyl polymers concentr...

Zinc oxide sol-containing diallylmethyl alkyl quaternary ammonium salt synthesized by sol–gel process: characterization and properties

Zinc oxide sols-containing quaternary ammonium bromide compounds, including diallylmethyl dodecyl/tetradecyl/hexadecyl/octadecyl ammonium bromide, were synthesized from zinc acetate and quaternary ammonium bromide compounds via sol–gel process. Effects of alkyl chain length and double allyl of quaternary ammonium salts on the stability of the sols were investigated. The sols were characterized by X-ray diffraction. Morphologies of the sols were observed with transmission electron microscopy. The various zinc oxide sols were applied to cotton fabrics. Antibacterial activity, UV resistance, and mechanical properties of the treated fabrics were tested. It was verified that alkyl chain length and double allyl of quaternary ammonium salts had effects on the stability of the sols. Application results showed that UV resistance and antibacterial rate of the fabric finished by zinc oxide sols-containing quaternary ammonium salts first increased and then decreased with an increase in the alkyl chain length of quaternary ammonium salts. However, the sols had negative effects on breaking strength and elongation at break of the fabric.

Synthesis and properties of modified rapeseed oil/montmorillonite nanocomposite fatliquoring agent

Modified rapeseed oil/montmorillonite (MRO/MMT) nanocomposite was prepared by using rapeseed oil, ethylene diamine, acrylic acid, and MMT. In order to compare MRO/MMT with MRO and a market product XQ-F3, they were applied in leather fatliquoring process, respectively. Sensory evaluation, physical and mechanical properties, and flame-retardant property of leather treated with different fatliquoring agents were measured. X-ray diffraction (XRD) results showed that MRO could smoothly enter the interlayer of MMT. The emulsifying property of MRO/MMT was confirmed better than that of MRO. The application results also showed that MRO/MMT has good fatliquoring effect. Meanwhile, it can increase leather strength and improve leather flame-retardant performance.

Synthesis and Characterization of VP/O-MMT Macromolecule Nanocomposite Material via Polymer Exfoliation—Adsorption Method

Vinyl polymer/montmorillonite nanocomposite (VP/O-MMT) is prepared by the solution exfoliation—adsorption method. The results of XRD, DSC, and TEM show that ion exchange has been successful between cetyl trimethylammonium bromide (CTAB) and montmorillonite (MMT) galleries, and the distance between the galleries of MMT has been increased from 1.0 to 1.9 nm, after exfoliation—adsorption by vinyl polymer. The distance can be increased to infinity. The glass transition temperature can be enhanced greatly and the melting peak is transferred to high temperatures; the thermal endurance of VP/O-MMT is also increased. An exfoliated structure is also formed. The TEM result of VP/O-MMT shows that MMT has been exfoliated by vinyl polymer matrix.

A star-shaped POSS-containing polymer for cleaner leather processing

A water-based silsesquioxane (POSS)-containing polymer, POSS-PAA, was synthesized by using octavinyl-POSS (V-POSS) and acrylic acid (AA) via interfacial polymerization. The TEM of POSS-PAA showed that the polymer formed a core-shell structure in aqueous solution and was well-dispersed. The star-shaped POSS-PAA and linear PAA were both tanned with 3.5% chromium tanning agent, and leather hide was tanned with 3.5% chromium tanning agent as a control. The results showed that the shrinkage temperature of wet-blue leather treated by POSS-PAA was increased by 3.5 °C than that of the control. The thickening rate of the POSS-PAA treated wet-blue leather samples was increased by 21% and 96% than the linear PAA-treated leather and the control leather, respectively. The EDS results suggested that the POSS-PAA pre-treated leather had a higher chromium content than the others, and the chromium distribution from the leather flesh side to the grain side was uniform. Moreover, the Cr2O3 content in both the POSS-PAA and the PAA pre-treated tanning waste water was reduced by about 50%, compared to the control waste. The COD and BOD of the POSS-PAA pre-tanning waste were decreased compared to the others. Therefore, POSS-PAA appeared to be promising for promoting the development of cleaner leather production.

Construction of durable antibacterial and anti-mildew cotton fabric based on P(DMDAAC-AGE)/Ag/ZnO composites

To prepare antibacterial cotton fabrics with laundering durability, an organic-inorganic P(DMDAAC-AGE)/Ag/ZnO composite was synthesized by free radical polymerization where the epoxy groups were utilized to form covalent bonds with the hydroxyl groups of cotton fabrics. The surface morphology, crystal phase and chemical structure of the obtained P(DMDAAC-AGE)/Ag/ZnO composite were characterized by XRD, FT-IR and TEM measurements. The resulting P(DMDAAC-AGE)/Ag/ZnO composite-functionalized cotton fabrics exhibited outstanding antibacterial activity and excellent laundering durability. In the antibacterial tests, the bacteriostatic reduction rate was greater than 99.75%, and remained over 99.00% even after 11 washing cycles (equivalent to 55 commercial or domestic laundering cycles). The antibacterial mechanism was also investigated, partly including release of ions and photocatalysis. Moreover, the coated cotton fabric possessed excellent anti-mildew performance and also maintained the basic properties of cotton fabric. These results suggest that the modified cotton fabrics may find potential applications in a wide variety of areas such as sportswears, socks, and medical textiles.

Modification of collagen with three novel tannages, sulfonated calix[4]arenes

Chromium (III) salts are the most extensively used tanning agents due to the higher quality and stabilization ability to leather collagen. However, chromium (III) salts tanning agent has a strong impact on the environment owing to the pollution of wastewater and the solid waste containing chrome. In order to crosslink the collagen by a cleaner method, three kinds of sulfonated calix[4]arenes {sulfonated calix[4]arene (SC), sulfonated tetraphenyl calix[4]resorcinarene (STCR), and sulfonated tetramethylene tetraphenyl calix[4]resorcinarene(STTCR)} were prepared and utilized for the collagen crosslinking and leather tanning. The collagen crosslinking degree of sulfonated calix[4]arenes was investigated by fourier transform infrared (FTIR), thermogravimetric analysis (TG), differential scanning calorimetry (DSC), scanning electron micrograph (SEM), and X-ray photoelectron spectroscopy (XPS). The results show that the collagen can be crosslinked by phenol hydroxyl groups on sulfonated calix[4]arenes. Moreover, STCR shows better crosslinking effects than others because the number of phenol hydroxyl groups and the position of sulfonic groups on sulfonated calix[4]arenes play important roles in the crosslinking process. These results can be confirmed by sulfonated calix[4]arenes tanning processes, and STCR tanned leather shows the higher shrinkage temperature. This paper provides a promising chrome-free method to reduce the pollution of chromium tanning waste.

Poly(quaternary ammonium salt-epoxy) grafted onto Ce doped ZnO composite: An enhanced and durable antibacterial agent

The composite after referred to as P(DMDAAC-AGE)/(Ce-ZnO) was prepared via free radical polymerization by polymer including quaternary ammonium salt and epoxy group which grafted onto the surface of Ce-ZnO. ZnO nanorods, Ce-ZnO nanorods, P(DMDAAC-AGE), P(DMDAAC-AGE)/ZnO composites, P(DMDAAC-AGE)/(Ce-ZnO) composites and commercial antimicrobials were respectively treated on the cotton fabrics and their biological properties were investigated. There is a synergistic effect between Ce-ZnO and N+ from the polymer in the fabric treated with P(DMDAAC-AGE)/(Ce-ZnO) composite so that it had a better antibacterial activity than pure polymer and pure Ce-ZnO. The antimicrobial rate of fabric treated with P(DMDAAC-AGE)/(Ce-ZnO) composite could reach up to 96%. And in order to investigate the durable ability, the fabric was washed multiple times to simulate the daily use washing. The result showed that the fabric still gave a superior antibacterial performance after 11 cycles (the equivalent of 55 times house laundering). Simultaneously, the differences in the amount of P(DMDAAC-AGE)/(Ce-ZnO) composite deposited on the fibers after washing were also investigated.

Fabrication of modified hydrogenated castor oil/GPTMS-ZnO composites and effect on UV resistance of leather

Leather products are made from the natural skin collagen fibers. It is vulnerable to the environmental factor such as solar ultraviolet irradiation in the using process. Therefore anti-UV performance is a very important quality, particularly for chrome-free leather. ZnO is a well-known UV absorber commonly used in the cosmetic industry. We have investigated its potential to increase the anti-UV performance of chrome-free leather. Modified hydrogenated castor oil/GPTMS-ZnO (MHCO/ GPTMS-ZnO) composites were prepared using spherical ZnO nanoparticles, hydrogenated castor oil, maleic anhydride and sodium bisulfite. MHCO/GPTMS-ZnO composites have better anti-UV ability and stability. MHCO/GPTMS-ZnO composites were applied to the leather processing. The treated samples were exposed to artificial sunlight. Anti-yellowing tests showed that MHCO/GPTMS-ZnO composites significantly improved anti-UV performance of leather.

Synthesis of PVP/IO-MMT Nanocomposite using Industrial Organic Montmorillonite

Industrial organic montmorillonite (IO-MMT) was characterized by X-ray diffraction (XRD) and thermogravimetry (TG). The results indicate that IO-MMT could prepare nanocomposite directly in theory. As dispersants, different nonionic surfactants were used to disperse IO-MMT. The result shows that nonionic surfactant TO-10 was selected as optimum dispersant. Then, vinyl polymer/industrial organic montmorillonite nanocomposite (PVP/IO-MMT) was prepared by vinyl polymer (PVP) and IO-MMT which dispersed in nonionic surfactant TO-10. The structure of PVP/IO-MMT nanocomposite was characterized by XRD and TEM. The result of XRD shows that the basal spacing d value of nanocomposite is 3.53 nm. The result of TEM indicates that composite was intercalated nanocomposite. Finally, PVP/IO-MMT was applied in the leather making process to examine its properties. The pickled sheepskin was tanned with 6% PVP/IO-MMT associated with 2% chromate, the shrinkage temperature of leather can be raised to 88°C. The application result...Industrial organic montmorillonite (IO-MMT) was characterized by X-ray diffraction (XRD) and thermogravimetry (TG). The results indicate that IO-MMT could prepare nanocomposite directly in theory. As dispersants, different nonionic surfactants were used to disperse IO-MMT. The result shows that nonionic surfactant TO-10 was selected as optimum dispersant. Then, vinyl polymer/industrial organic montmorillonite nanocomposite (PVP/IO-MMT) was prepared by vinyl polymer (PVP) and IO-MMT which dispersed in nonionic surfactant TO-10. The structure of PVP/IO-MMT nanocomposite was characterized by XRD and TEM. The result of XRD shows that the basal spacing d value of nanocomposite is 3.53 nm. The result of TEM indicates that composite was intercalated nanocomposite. Finally, PVP/IO-MMT was applied in the leather making process to examine its properties. The pickled sheepskin was tanned with 6% PVP/IO-MMT associated with 2% chromate, the shrinkage temperature of leather can be raised to 88°C. The application results show that it is an effective way to decrease the use of chromate for nanocomposites.