Silsesquioxane 3-n-Propylpyridinium chloride: a new polymer for the potentiometric analysis of Cr(VI) in electroplating and leather industry wastes

A new polymer, silsesquioxane 3-n-propylpyridinium chloride (SiPy+Cl-), was used in the preparation of an electrode. The polymer coated graphite rod ion selective electrode for Cr(VI) was constructed and evaluated for the determination of Cr(VI) in samples of electroplating and leather industry wastes. This electrode exhibited a Nernstian response for Cr(VI) concentrations between 3.1<FONT FACE=Symbol>&acute;</FONT>10-6 and 1.8<FONT FACE=Symbol>&acute;</FONT>10-2 mol L-1 and a detection limit of 2.8<FONT FACE=Symbol>&acute;</FONT>10-6 mol L-1 (0.15 ppm). The response of the electrode for Cr(VI) was fast (15 s) and the independent potential of pH in the range of 3.0 to 7.0. The selectivity coefficients for several anions showed that the electrode presents excellent performance. The sensor exhibits a shelf-life of 6 months with good reproducibility. Determination of Cr(VI) in electroplating and leather wastes using the sensor was successfully achieved

Ammonium ion sensor based on SiO2/ZrO2/phosphate-NH4+ composite for quantification of ammonium ions in natural waters

Ion selective-electrode was constructed and evaluated for determination of ammonium ions in natural waters. The electrode consists of paste carbon with the composite SiO2/ZrO2/phosphate-NH4+ obtained through sol-gel process. The electrode exhibits a sub-Nernstian response for ammonium concentrations between 7.7<FONT FACE=Symbol>&acute;</FONT>10-7 and 4.0<FONT FACE=Symbol>&acute;</FONT>10-2 mol L-1 and a detection limit of 1.58<FONT FACE=Symbol>&acute;</FONT>10-7 mol L-1 (8.5<FONT FACE=Symbol>&acute;</FONT>10-3 ppm). The electrode response for ammonium was fast (1 minute). The selectivity coefficients KpotA,B for several ions usually present in natural waters were determined applying the matched potential method. The potentiometric method with the ion selective electrode was validated by the Berthelot method (standard method), through the determination of ammonium ions in natural waters. The ion selective-electrode proved suitable for routine quality control of natural waters by potentiometry

Adsorption Of Metal Halides From Ethanol Solutions By A 3-n-propylpyridiniumsilsesquioxane Chloride-coated Silica Gel Surface.

3-n-propylpyridiniumsilsesquioxane chloride polymer, abbreviated as SiPy+Cl-, was used to coat a porous silica gel, SiO2, surface to form the chemically modified solid SiO2/SiPy+Cl-. The resulting polymer film was well adhered to the surface and presented an ion exchange capacity of 0.74 mmol g(-1). Metal halides, MClz [M=Fe(III), Cu(II), and Zn(II)], were adsorbed by the modified solid from ethanol solutions as neutral species by forming the surface anionic complexes described by the equation: mSiO2/SiPy+Cl-+ MClz (SiO2/SiPy+)m[MCl(z+m)]m-, where the [MCl(z+m)]m- species adsorbed on the surface are FeCl4-, ZnCl4(2-), and CuCl4(2-). Accurate estimates of the specific sorption capacities and the heterogeneous stability constants of the immobilized metal complexes were determined with the aid of computational procedures.26932-

Ammonium ion sensor based on SiO2/ZrO2/phosphate-NH4+ composite for quantification of ammonium ions in natural waters

Ion selective-electrode was constructed and evaluated for determination of ammonium ions in natural waters. The electrode consists of paste carbon with the composite SiO2/ZrO2/phosphate-NH4+ obtained through sol-gel process. The electrode exhibits a sub-Nernstian response for ammonium concentrations between 7.7&acute;10-7 and 4.0&acute;10-2 mol L-1 and a detection limit of 1.58&acute;10-7 mol L-1 (8.5&acute;10-3 ppm). The electrode response for ammonium was fast (1 minute). The selectivity coefficients KpotA,B for several ions usually present in natural waters were determined applying the matched potential method. The potentiometric method with the ion selective electrode was validated by the Berthelot method (standard method), through the determination of ammonium ions in natural waters. The ion selective-electrode proved suitable for routine quality control of natural waters by potentiometry.Um eletrodo íon seletivo foi construído e avaliado para determinação de íons amônio em águas naturais. O eletrodo consiste de uma pasta de carbono com o compósito SiO2/ZrO2/fosfato-NH4+ obtido pelo processo de sol-gel. O eletrodo exibe uma resposta sub-Nenstiana para concentrações entre 7,7&acute;10-7 e 4,0&acute;10-2 mol L-1 e um limite de detecção de 1,58&acute;10-7 mol L-1 (8,5&acute;10-3 ppm). A resposta do eletrodo foi rápida (1 minuto). Os coeficientes de seletividade KpotA,B para os diversos íons geralmente presentes em águas naturais foram determinados pela aplicação do matched potential method. O método potenciométrico com o eletrodo íon seletivo foi validado pelo método de Berthelot (método padrão) pela determinação de íons amônio em águas naturais. O eletrodo íon seletivo provou ser satisfatório para o controle de qualidade de águas naturais.18919