Determination of Ni^(2+) in Waters with Sodium Polyacrylate as a Binding Phase in Diffusive Gradients in Thin-films

An aqueous solution containing sodium polyacrylate（PAAS） was used in diffusive gradient in thin-films technique（DGT） to measure DGT-labile Ni2＋ concentrations.The DGT devices（PAAS DGT） were validated in four types of solutions,including synthetic river water containing metal ions with complexing EDTA or that without complexing EDTA,natural river water（Ling River,Jinzhou,China） spiked with Ni2＋,and an industrial wastewater （Jinzhou,China）.Results show that only free metal ions were measured by PAAS DGT,recovery=97.36% in the solutions containing only free metal ions,recovery=49.62% in a solution with metal/EDTA molar ratio of 2：1 and recovery=0 in the solutions with metal/EDTA molar ratios of 1：1 and 1：2.These indicated that the complexes of Ni-EDTA were DGT-inert.The DGT performance in spiked river water（recovery=18.24%） and in industrial wastewater（recovery=12.25%） were investigated,which indicated that the measurement of metals by this DGT device did not include the humic substances complexed fractions of metals.The binding properties of PAAS DGT for Ni2＋ were investigated under different conditions of pH value and ionic strength.Conditional stability constants（lgK） of PAAS-Ni complexes were also evaluated.

Flocculation Mechanism of Synthetic Goethite Suspension Using Hydroxamated Polymer and Sodium Polyacrylate

The flocculation effects of homemade hydroxamated flocculant(HPAA)and commercially available sodium polyacrylate(PAAS)on synthetic goethite suspensions with different solid contents were studied.The adsorption mechanism of HPAA or PAAS on the surfaces of goethite was investigated.The settling rate of 50 g/L goethite suspension with HPAA(1.74 m/h)was faster than that with PAAS(0.54 m/h),which indicated that HPAA exhibits better flocculation performance than PAAS does.It could be found that the stretching vibration of carbonyl band in hydroxamic acid groups of HPAA was downshifted from 1 654 cm^(-1) to 1 645 cm^(-1) and a new adsorption band appeared at 1 455 cm-1,which demonstrated that a five-membered ring chelate may be formed among iron atoms of goethite surfaces,the hydroxyl groups and the carbonyl groups in hydroxamic acid groups of HPAA.In the case of PAAS,the separation of the asymmetric and symmetric stretches of the carboxylate groups in adsorbed PAAS was 163 cm-1,which was greater than that of unadsorbed PAAS with 157 cm^(-1).There was no indication of a contribution from the monodentate adsorption between iron atoms of goethite surfaces and carboxylate groups of PAAS,but there may exist a bi-dentate bridging structure.Compared with synthetic goethite,XPS curve fittings of Fe 2p spectra showed that the binding energies of the main Fe 2p3/2 and Fe 2p1/2 resolved peaks on HPAA-treated goethite surfaces were correspondingly decreased by 0.9 and 0.7 e V,while those on PAAS-treated goethite surfaces were correspondingly decreased by 0.7 and 0.3 e V.The characteristic N 1s peak of HPAA and C 1s peak of PAAS were correspondingly detected on HPAA-treated and PAAS-treated goethites,and a binding energy change of N 1s spectrum of adsorbed HPAA was observed.The relative atomic ratios of C/Fe,N/Fe and O/Fe on HPAA-treated and PAAS-treated goethite surfaces were increased.All the results suggested that HPAA or PAAS was adsorbed on the goethite surfaces by the chemisorption,and a stronger adsorption of HPAA on the goethite surfaces happened than that of PAAS.

Influnence of Sodium Polyacrylate on Crystallization and Aggregation of Butterfly-like Calcium Carbonate

Butterfly-like calcium carbonate（CaCO3） particles were successfully prepared via a facile precipitation reaction of Na2CO3 with CaCI2 in the presence of sodium polyacrylate（PAAS）. The as-prepared samples were cha- racterized with field emission scanning electron microscopy（FESEM）, X-ray diffraction（XRD） and Fourier transform infrared spectroscopy（FTIR）. Butterfly-like CaCO3 particles composed of three segment rods were obtained. Rod aggregates would act as the template for butterfly-like CaCO3 crystals consisted of regular shaped crystallites with 150--200 nm in diameter. The influences of reaction temperature, the amount of PAAS and reaction time on the nucleation and growth of CaCO3 crystals were investigated. The possible growth mechanism of CaCO3 crystals was discussed. This research can not onty make us further understand the general principles of the reaction, but also open up a new avenue of industrial production of CaCO3 particles with exquisite and unique morphologies.

Electrical Characteristics of Super Capacitors Using KOH Gel

Despite aqueous electrolytes having a low cost and excellent ionic conductivity,their low withstand voltage of 1.2 V makes them problematic for battery utility because that is a very important factor in battery production.In this research,the possibility of increasing the withstand voltage while maintaining the low cost of aqueous electrolytes was investigated.In this research,the solution electrolyte was made into a viscous solid polymer electrolyte to improve the withstand voltage of the electrolyte.A solid polymer electrolyte was made from sodium polyacrylate and doped with KOH(potassium hydroxide)and pure water.The improvement of the withstand voltage was evaluated by the specific capacitance.

Roles of polyacrylate dispersant in the synthesis of well-dispersed BaSO_4 nanoparticles by simple precipitation

Well-dispersed BaSO4 nanoparticles were synthesized in the presence of sodium polyacrylate （PAAS） by a simple precipitation method, with BaCl2 and （NH4）2SO4 as reactants. The different roles performed by PAAS in the synthesis of BaSO4 nanoparticles were investigated using X-ray diffractometry, Fourier transform infrared spectroscopy, and transmission electron microscopy. The results indicate that the assynthesized BaSO4 nanoparticles were spheres with an average diameter of 30 nm and that their surfaces were affected by the PAAS. Under a typical procedure employed, PAAS reacted with BaCl2 to yield an intermediate, serving as a control releasing agent and separating the nucleation and crystal growth processes of the BaSO4 nuclei. During formation of the BaSO4 nanospheres, the intermediate slowly dissolved and released barium and polyacrylate ions, inhibiting the growth and aggregation of newly formed BaSO4 seeds and resulting in particles of narrow diameter distribution and improved dispersibility. Moreover, these polyacrylate ions further modified the surfaces of the BaSO4 nanoparticles.

Preparation of transparent Y_2O_3 ceramic by slip casting and vacuum sintering

In the present work transparent Y2O3 ceramics were made by slip casting and vacuum sintering of nanopowders with sodium poly-acrylic acid（PAA-Na） as dispersant.The rheological properties of Y2O3 nanopowder slurry were investigated using different amounts of dis-persant and solid contents.The microstructures and transmittance of the sintered ceramics were also studied by means of scanning electron microscopy（SEM） and ultra-violet visible spectrometry.The results showed that rheological behaviors of the Y2O3 nanopowder slurry were effectively promoted by sodium polyacrylic acid.Highly dispersive and stable slurries were obtained as the dispersant was added over 1.0 dwb% under the fixed conditions of pH 11 and 45 wt.% solid content.All the slip cast green bodies were sintered into highly dense ceramics after sintering at 1700 oC for 5 h in vacuum,wherein the sample added with 1.1% sodium polyacrylic acid exhibited the highest relative den-sity of 99.36% and transmission of 30% at 800 nm wavelength.

Blood Compatibility of Nano-Hydroxyapatite Dispersed Using Various Agents

Nano-hydroxyapatite (nHAP),dispersed with three kinds of dispersants (heparin sodium,polyacrylic sodium and wa-ter),reacted with red blood cell,Bel-7402 tumor cell,to compare their dispersing efficiency against nHAP from one another. The blood compatibility of nHAP is also determined by blood solubil-ity experiment so that the capability of different dispersant dis-persing against nHAP of different concentration and the relation between nHAP and blood compatibility have been determined. The inhibiting function of Bel-7402 against tumor cells is deter-mined with the MTT staining method. The study result shows that heparin sodium has the best dispersing efficiency for nHAP with-out the phenomenon of hemolysis.