Stabilization Mechanisms and Reaction Sequences for Sintering Simulated Copper-Laden Sludge with Alumina

To stabilize copper-laden sludge using alumina-based ceramic raw materials, this study quantifies the copper transformation behavior during the sintering process. Results indicate crystallochemical incorporation of hazardous copper through the formation of copper aluminate spinel (CuAl₂O₄) and cuprous aluminate (CuAlO₂). To quantify the copper transformation and reveal reaction sequences, CuO was mixed with γ-Al₂O₃ and α-Al₂O₃ precursors and fired at 1050–1150 °C for 15–180 min. The sintered products were examined using X-ray diffraction (XRD), and copper transformations into both aluminate phases were quantitatively determined through Rietveld refinement analysis of XRD data. When γ-Al₂O₃ was used, CuAlO₂ was predominately generated from CuAl₂O₄ decomposition. However, CuAlO₂ was largely generated by the interaction between CuO and α-Al₂O₃. This study also compared the sintering behavior of both precursor systems and observed the relatively slower decomposition of CuAl₂O₄ in the γ-Al₂O₃ system. The reoxidation of CuAlO₂ into CuAl₂O₄ with an extended sintering time was detected in the α-Al₂O₃ system. The sample leachability analysis reveals that both CuAl₂O₄ and CuAlO₂ structures were superior in copper stabilization compared to the oxide forms. Such results suggest reliable mechanisms of incorporating hazardous copper into a ceramic matrix and demonstrate the potential of using waste materials as part of ceramic raw materials to produce detoxified products

Combined Fe₂O₃ and CaCO₃ Additives To Enhance the Immobilization of Pb in Cathode Ray Tube Funnel Glass

Cathode ray tube (CRT) funnel glass has posed an increasing threat to the environment due to its rapid replacement by new technology in recent years. In this study, a well-control thermal scheme was applied for synthesizing a specific crystalline phase, PbFe₁₂O₁₉, for Pb immobilization when reusing CRT funnel glass as raw materials for the ceramics industry. The Fourier transform infrared spectroscopy results show that introduction of CaCO₃ facilitated the breakage of strongly connected bonds between O–Si–O and Pb–O, which were firmly linked in the glass network. The X-ray diffraction results demonstrate that 30 wt % CaCO₃ loading effectively facilitated the transformation of Pb in CRT funnel glass to the stable-phase PbFe₁₂O₁₉. A higher sintering temperature increased Pb transformation efficiency while a longer dwelling time only showed a slight increase in PbFe₁₂O₁₉ formation. The prolonged toxic characteristic leaching procedure results show a substantial improvement in the acid resistance (approximately 2 mg/L) of the thermally treated product with 30 wt % CaCO₃ loading and sintering under 1000 °C for 5 h compared to the original CRT funnel glass (500 mg/L). The results of this study demonstrate that incorporation of CaCO₃ and Fe₂O₃ into CRT funnel glass can effectively promote Pb immobilization and provide a new strategy for stabilizing waste CRT funnel glass

Copper Sludge from Printed Circuit Board Production/Recycling for Ceramic Materials: A Quantitative Analysis of Copper Transformation and Immobilization

The fast development of electronic industries and stringent requirement of recycling waste electronics have produced a large amount of metal-containing waste sludge. This study developed a waste-to-resource strategy to beneficially use such metal-containing sludge from the production and recycling processes of printed circuit board (PCBs). To observe the metal incorporation mechanisms and phase transformation processes, mixtures of copper industrial waste sludge and kaolinite-based materials (kaolinite and mullite) were fired between 650 and 1250 °C for 3 h. The different copper-hosting phases were identified by powder X-ray diffraction (XRD) in the sintered products, and CuAl₂O₄ was found to be the predominant hosting phase throughout the reactions, regardless of the strong reduction potential of copper expected at high temperatures. The experimental results indicated that CuAl₂O₄ was generated more easily and in larger quantities at low-temperature processing when using the kaolinite precursor. Maximum copper transformations reached 86% and 97% for kaolinite and mullite systems, respectively, when sintering at 1000 °C. To monitor the stabilization effect after thermal process, prolonged leaching tests were carried out using acetic acid with an initial pH value of 2.9 to leach the sintered products for 20 days. The results demonstrated the decrease of copper leachability with the formation of CuAl₂O₄, despite different sintering behavior in kaolinite and mullite systems. This study clearly indicates spinel formation as the most crucial metal stabilization mechanism when sintering copper sludge with aluminosilicate materials, and suggests a promising and reliable technique for reusing metal-containing sludge as ceramic materials

Crystal Structures of Al–Nd Codoped Zirconolite Derived from Glass Matrix and Powder Sintering

Zirconolite is a candidate host for immobilizing long-lived radionuclides. Zirconolite-based glass-ceramics in the CaO-SiO₂-Al₂O₃-TiO₂-ZrO₂-Nd₂O₃-Na₂O matrix are a potential waste form for immobilizing actinide radionuclides and can offer double barriers to immobilize radioactive elements. However, the X-ray diffraction patterns of the zirconolite derived from the glass matrix (glass ceramic, GC) are significantly different from those prepared by powder sintering (PS). In this Article, the crystal structures of Al–Nd codoped zirconolite grown via the glass matrix route and the powder sintering route are investigated in detail. Two samples of Al–Nd codoped zirconolite were prepared: one was grown from a CaO-SiO₂-Al₂O₃-TiO₂-ZrO₂-Nd₂O₃-Na₂O glass matrix, and the other was prepared with a Ca_0.75Nd_0.25Zr­Ti_1.75Al_0.25O₇ composition by powder sintering. The samples were then characterized using powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), transmission electron microscopy–energy dispersive X-ray spectroscopy (TEM-EDX), and selected area electron diffraction (SAED). The chemical composition of the 100–500 nm zirconolite crystals grown from a glass matrix was determined by TEM-EDX to be Ca_0.83Nd_0.25Zr_0.85­Ti_1.95Al_0.11O₇. PXRD and SAED results showed that these two Al–Nd codoped zirconolite phases were crystallized in space group <i>C</i>12/<i>c</i>1. The HRTEM images and SAED results showed that there were heavy stacking faults in the zirconolite crystals grown from the glass matrix. In contrast, far fewer defects were found in the zirconolite crystals prepared by powder sintering. The split-atom model was adopted for the first time to construct the Al–Nd codoped zirconolite structure grown from glass during the Rietveld refinement. The isostructural method assisted by Rietveld refinement was used to resolve the Al–Nd codoped zirconolite structures prepared by different methods. The occupancies of the cation sites were identified, and the distribution behavior of Nd³⁺ was further investigated. The results indicate that the heavy stacking faults may lead to substantial differences in the Al–Nd codoped zirconolite structures prepared by these two fabrication routes

Extraction of Metallic Lead from Cathode Ray Tube (CRT) Funnel Glass by Thermal Reduction with Metallic Iron

A novel and effective process of thermal reduction treatment with the addition of metallic iron (Fe(0)) to recover lead from cathode ray tube (CRT) funnel glass is introduced. The key technological breakthrough of this process is the use of a relatively lower temperature and an inexpensive reducing agent to extract the metallic lead. The influences of temperature, the reducing agent content, and the holding time for lead reduction were examined to determine the optimal extraction efficiency. The lead extraction efficiency first increased and then decreased with increasing temperature. The maximum lead extraction efficiency occurred at 700 °C. The growth of crystalline lead first increased significantly with an increase in the Fe content, reaching maximum growth at an Fe addition of 50 wt %. The most effective treatment time was determined to be 30 min, as the vitrification of lead back to the glass matrix occurred under longer treatment times. The experimentally derived results indicate that a 58 wt % lead extraction can be achieved with the optimized operational parameters (50 wt % Fe addition, heating at 700 °C for 30 min) in a single extraction operation

Mineralization Behavior of Fluorine in Perfluorooctanesulfonate (PFOS) during Thermal Treatment of Lime-Conditioned Sludge

The fate and transport of the fluorine in perfluorooctanesulfonate (PFOS) during the thermal treatment of lime-conditioned sludge were observed using both qualitative and quantitative X-ray diffraction techniques. Two main fluorine mineralization mechanisms leading to the substantial formation of CaF₂ and Ca₅(PO₄)₃F phases were observed. They had a close relationship with the thermal treatment condition and the PFOS content of the sludge. At low temperatures (300–600 °C), CaF₂ dominated in the product and increases in treatment time and temperature generally enhanced the fluorine transformation. However, at higher temperatures (700–900 °C), increases in treatment time and temperature had a negative effect on the overall efficiency of the fluorine crystallization. The results suggest that in the high temperature environment there were greater losses of gaseous products such as HF and SiF₄ in the transformation of CaF₂ to Ca₅(PO₄)₃F, the hydrolysis of CaF₂, and the reaction with SiO₂. The quantitative analysis also showed that when treating sludge with low PFOS content at high temperatures, the formation of Ca₅(PO₄)₃F may be the primary mechanism for the mineralization of the fluorine in PFOS. The overall results clearly indicate the variations in the fate and transport of fluorine in PFOS when the sludge is subject to different PFOS contents and treatment types, such as heat drying or incineration

Prevalência de HPV em material cérvico-uterino de mulheres de Tomé-Açú – PA

The human papillomavirus (HPV) infects basal of stratified epithelium and develop proliferative benign lesions in skin or mucous. The infection has a universal distribution however many studies have demonstrated a strong association of infections by high risk species in cases of cervical cancer. In Brazil, this type of cancer is the second most common among women, while the north and northeast region of this country have the highest incidence. Therefore, this study has as focus the determination of infection prevalence in a group of women screened to cervical cancer. During the period of July 2008 to March 2009 were collected cervical samples from 144 women received at Laboratório de Citopatologia of Hospital Amazônia from Quatro Bocas, Tomé-Açú, Pará. All women were informed about the purpose of that research and then signed the Consent Form and answered the epidemiological questionnaire. The data obtained from the questionnaire correlated with the infection through the testing qui -quadradot. The HPV prevalence was 6,94% and the majority age was between 18-28 years. Samples from 76 patients showed inflammatory aspect (52,02%) and 60 patients did not showed any change (41,09%). Among smears with cytological ASC-US in the most of cases (6/10) followed by LSIL (2/10), and ASC-H (1/10) and HSIL (1/10). The HPV infection is statistically significant correlated PCR-HPV test with the age group, and cytomorphology. Prevalence found in this study corroborants with other findings reported in the literature. The predominance of infection in women with abnormal cytology strengthens the concept that infection is, in most of cases, asymptomatic, and the Pap smear method is lesser efficient to detect infection than techniques of molecular biolology.O Papilomavirus humano infecta as células basais do epitélio estratificado, induzindo a lesões proliferativas benignas na pele ou mucosas. As infecções apresentam distribuição universal, no entanto muitos estudos têm demonstrado a forte associação da infecção por espécies de alto risco com casos de câncer cervical. No Brasil, esse tipo de câncer é o segundo tipo mais comum entre as mulheres, sendo que as regiões norte e nordeste do país apresentam a maior incidência. O presente estudo visou determinar a prevalência da infecção em um grupo de mulheres rastreadas para o câncer cervical. No período de julho de 2008 a março de 2009 foram coletadas amostras cervicais de 144 mulheres atendidas no Laboratório de Citopatologia do Hospital Amazônia de Quatro Bocas, Tomé – Açu, estado do Pará. Os dados obtidos foram correlacionados com a infecção através do teste do qui-quadrado. A Prevalência do HPV foi de 6,94%, a idade variou em 18 -28 anos, 76 pacientes apresentaram quadro inflamatório, ou seja, 52,05%, enquanto que 60 pacientes não apresentaram alteração, com 41,09% do total. Dentre os esfregaços com alterações citológicas, ASC-US foi encontrado na maioria dos casos, (6/10), seguido de LSIL (2/10), e ASC-H (1/10), e HSIL (1/10). A infecção pelo HPV mostrou associação estatisticamente significativa com a PCR, faixa etária e citomorfologia. A prevalência encontrada no estudo corrobora com outros achados descritos na literatura. A predominância da infecção em mulheres com citologia anormal reforça a ideia de que a infecção é, em sua maioria, assintomática e que o método de Papanicolau é menos eficiente na detecção da infecção em relação às técnicas de biologia molecular

Cu₂O-promoted degradation of sulfamethoxazole by <i>α</i>-Fe₂O₃-catalyzed peroxymonosulfate under circumneutral conditions: synergistic effect, Cu/Fe ratios, and mechanisms

<p>To promote the application of iron oxides in sulfate radical-based advanced oxidation processes, a convenient approach using Cu₂O as a catalyst additive was proposed. Composite catalysts based on <i>α</i>-Fe₂O₃ (CTX%Cu₂O, <i>X</i> = 1, 2.5, 5, and 10) were prepared for peroxymonosulfate (PMS) activation, and sulfamethoxazole was used as a model pollutant to probe the catalytic reactivity. The results show that a synergistic catalytic effect exists between Cu₂O and <i>α</i>-Fe₂O₃, which was explained by the promoted reduction of Fe(III) by Cu(I). Iron K-edge X-ray absorption spectroscopy investigations indicated that the promoted reduction probably occurred with PMS acting as a ligand that bridges the redox centers of Cu(I) and Fe(III). The weight ratio between Cu₂O and <i>α</i>-Fe₂O₃ influenced the degradation of sulfamethoxazole, and the optimal ratio depended on the dosage of PMS and catalysts. With 40 mg L^–1 PMS and 0.6 g L^–1 catalyst, a pseudo-first-order constant of ∼0.019 min^–1 was achieved for CT2.5%Cu₂O, whereas only 0.004 min^–1 was realized for <i>α</i>-Fe₂O₃. Nearly complete degradation of the sulfamethoxazole was achieved within 180 min under the conditions of 40 mg L^–1 PMS, 0.4 g L^–1 CT2.5%Cu₂O, and pH 6.8. In contrast, less than 20% degradation was realized with <i>α</i>-Fe₂O₃ under similar conditions. The CT2.5%Cu₂O catalyst had the best stoichiometric efficiency of PMS (0.317), which was 4.5 and 5.8 times higher than those of Cu₂O (0.070) and <i>α</i>-Fe₂O₃ (0.054), respectively. On the basis of the products identified, the cleavage of the S–N bond was proposed as a major pathway for the degradation of sulfamethoxazole.</p

Cadmium Stabilization Efficiency and Leachability by CdAl₄O₇ Monoclinic Structure

This study investigated the stabilization efficiencies of using an aluminum-rich precursor to incorporate simulated cadmium-bearing waste sludge and evaluated the leaching performance of the product phase. Cadmium oxide and γ-alumina mixtures with various Cd/Al molar ratios were fired at 800–1000 °C for 3 h. Cadmium could be crystallochemically incorporated by γ-alumina into CdAl₄O₇ monoclinic phase and the reaction was strongly controlled by the treatment temperature. The crystal structure details of CdAl₄O₇ were solved and refined with the Rietveld refinement method. According to the structural refinement results, the stabilization efficiencies were quantified and expressed as a transformation ratio (TR) with optimized processing parameters. The preferred treatment temperature was found to be 950 °C for mixtures with a Cd/Al molar ratio of 1/4, as its TR value indicated the cadmium incorporation was nearly completed after a 3 h treatment scheme. Constant-pH leaching tests (CPLT) were conducted by comparing the leachability of the CdO and CdAl₄O₇ phases in a pH 4.0 environment. A remarkable reduction in cadmium leachability could be achieved via monoclinic CdAl₄O₇ structure formation to effectively stabilize hazardous cadmium in the waste stream. The CPLT and X-ray photoelectron spectroscopy (XPS) results suggested incongruent dissolution behavior during the leaching of the CdAl₄O₇ phase

Summary results of 3-way ANOVA showing the <i>F</i>-ratios for the main and interactive effects of pH (8.1 and 7.8), salinity (27 and 34 ‰) and temperature (23°C and 29°C) on (1) tube composition in terms of amorphous CaCO₃, calcite/aragonite ratio, Mg/Ca ratio, Sr/Ca ratio, and (2) mechanical properties, in terms of hardness and elasticity.

<p>Significant effects (<i>p</i><0.05) are indicated in bold. Detailed information of ANOVA results are provided in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0078945#pone.0078945.s001" target="_blank">tables S1</a> to <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0078945#pone.0078945.s003" target="_blank">S3</a>. pH×Sal: 7.8 and 27, pH×T: 7.8 and 29; Sal×T: 27×29; pH×Sal×T: 7.8×27×29.</p>*<p>As Mg/Ca ratio did not fulfill requirement of variance homogeneity, the critical p-value was adjusted to a more conservative value of p<0.01.</p