Comparação do teor de cloro ativo e pH do hipoclorito de sódio 0, 5% fabricado e manipulado / Comparison of active chlorine and pH of manufactured and manipulated sodium hypochlorite 0.5%

O objetivo deste estudo foi verificar a real concentração de cloro ativo e pH do hipoclorito de sódio a 0,5% fabricado e manipulado. Foram analisadas 10 amostras de hipoclorito de sódio 0,5%, sendo 5 adquiridas em comércio e outros 5 em farmácias de manipulação. As amostras foram armazenadas em frascos de vidro âmbar e mantidas em caixa de isopor. Assim, foi realizada a medição de pH com um pHmetro, e o cloro ativo por titulometria. Os dados foram submetidos ao teste de Mann-Whitney (p=0.05). A medição de pH variou de 7.7 a 11.5, com média de 9.45, e em relação à concentração de cloro ativo houve uma variação de 0,04% a 0,45%. A análise estatística não apresentou diferença significante entre os grupos. Pode-se concluir que hipoclorito de sódio 0,5% manipulado e vendido comercialmente não se diferiu entre si em relação à sua concentração, no entanto, há falta de controle entre alguns fabricantes/manipuladores quanto à real concentração de cloro ativo. Maior parte dos produtos comercializados possui pH dentro do proposto na literatura...

The aim of this study was to verify the actual concentration of active chlorine and pH of manufactured and manipulated sodium hypochlorite 0.5%. Ten samples of the sodium hypochlorite 0.5% were analyzed, 5 manufactured and other 5 manipulated. The samples were stored in amber glass bottles and styrofoam box. Then, it was performed the pH measurement using a pHmeter, and the active chlorine by titrimetry. The data were submitted to Mann-Whitney test (p=0.05). PH measuring ranged from 7.7 to 11.5, with a mean of 9.45, and active chlorine concentration ranged from 0.04% to 0.45%. There was no significant difference between the groups. It can be concluded that manufactured and manipulated sodium hypochlorite 0.5% did not differ regarding concentration, and there is no control of concentration for both manufacturer and manipulator. Most of manufactured and manipulated products presented pH in accordance to that proposed in the literature...

Disinfection of wastewater: comparative evaluation of chlorination and DHS-biotower.

The present study reports the onsite evaluation of two pilot scale disinfection units. One of the pilot plants is based on chlorination, and other is based on fixed film aerobic process (biotower). Evaluation study consisted of onsite monitoring of COD, BOD5 and TSS and fecal coliform over a period of three months. Samples were collected from the inlet and outlet of the pilot plants. These pilot plants were evaluated so as to have an appropriate disinfection technology for the treatment of the effluents from upflow anaerobic sludge blanket reactor (UASBR) based sewage treatment plants which could meet the biological quality standards. All the influents samples collected from both the pilot plants contained fecal coliform ranging from 105 to 10(6) MPN/100 ml. The results show that the fecal coliform removal is up to 98.2% and 100% forbiotower and chlorination, respectively. Both, the chlorination and down hanging sponge-biotower (DHS-biotower) improved the quality of effluent from the UASBRin terms of COD, BOD5 and TSS. Though chlorination performed better compared to the DHS-biotower, however, it has additional risk associated with the formation of trihalomethanes (THMs).

Effect of microwave disinfection on denture base adaptation and resin surface roughness

This study evaluated the effect of disinfection methods [chemical disinfection (immersion in 100 ppm chloride solution) or microwave disinfection (690 W for 6 min)] on the internal adaptation of denture bases and resin surface roughness. For the adaptation test, 18 maxillary denture bases were obtained from stone casts duplicated from a metallic master model and submitted to the following treatments: 1) control (no disinfection), 2) chemical disinfection or 3) microwave disinfection. Disinfection procedures were performed twice (T1, T2) with a 7-day interval between them. Internal adaptation was measured at baseline (T0) and after T1 and T2 by weighing a vinyl polysiloxane film reproducing the gap between the resin base and the master model. For surface roughness measurement, 60 rectangular (5x10x40 mm) resin specimens were either mechanically or chemically polished and then submitted to the disinfection treatments. Surface roughness (Ra) was recorded after polishing (T0) and after T1 and T2. Data were analyzed by ANOVA GLM for repeated measures and Bonferroni correction at 5 percent significance level. Bases submitted to microwave disinfection had gradual increase of misfit, while bases immersed in chloride solution did not differ from the control group. Surface roughness increased in the mechanical polishing groups with microwave disinfection and decreased in the chemical polishing groups.

Este estudo avaliou o efeito de métodos de desinfecção [desinfecção química (imersão em solução clorada 100 ppm) ou desinfecção por microondas (690 W por 6 min)] na adaptação interna de bases de próteses totais e na rugosidade superficial da resina. Para o teste de adaptação, 18 bases superiores foram duplicadas a partir de um modelo-mestre metálico e submetidas aos seguintes tratamentos: 1) controle (sem desinfecção), 2) desinfecção química ou 3) desinfecção por microondas. Os procedimentos de desinfecção foram realizados duas vezes (T1, T2) com intervalo de 7 dias. A adaptação interna foi medida no baseline (T0), após T1 e T2 por pesagem de um filme de silicona de adição que reproduzia o espaço entre base de resina e modelo-mestre. Para a rugosidade superficial, 60 espécimes retangulares (5x10x40 mm) receberam polimento mecânico ou químico e foram submetidos aos tratamentos de desinfecção. A rugosidade superficial (Ra) foi registrada após o polimento (T0) e após T1 e T2. Os dados foram analisados por ANOVA GLM para medições repetidas e teste de Bonferroni com nível de significância de 5 por cento. As bases submetidas à desinfecção por microondas tiveram aumento gradual de desadaptação, enquanto que as bases imersas em solução clorada não diferiram do grupo controle. A rugosidade superficial aumentou nos grupos de polimento mecânico e desinfecção por microondas e diminuiu nos grupos de polimento químico.