Nanoparticle exposure and hazard in the ceramic industry: an overview of potential sources, toxicity and health effects.

The ceramic industry is an industrial sector of great impact in the global economy that has been benefiting from advances in materials and processing technologies. Ceramic manufacturing has a strong potential for airborne particle formation and emission, namely of ultrafine particles (UFP) and nanoparticles (NP), meaning that workers of those industries are at risk of potential exposure to these particles. At present, little is known on the impact of engineered nanoparticles (ENP) on the environment and human health and no established Occupational Exposure Limits (OEL) or specific regulations to airborne nanoparticles (ANP) exposure exist raising concerns about the possible consequences of such exposure. In this paper, we provide an overview of the current knowledge on occupational exposure to NP in the ceramic industry and their impact on human health. Possible sources and exposure scenarios, a summary of the existing methods for evaluation and monitoring of ANP in the workplace environment and proposed Nano Reference Values (NRV) for different classes of NP are presented. Case studies on occupational exposure to ANP generated at different stages of the ceramic manufacturing process are described. Finally, the toxicological potential of intentional and unintentional ANP that have been identified in the ceramic industry workplace environment is discussed based on the existing evidence from in vitro and in vivo inhalation toxicity studies.

Comparison of radical-driven technologies applied for paraben mixture degradation: mechanism, biodegradability, toxicity and cost assessment.

Parabens (esters of p-hydroxybenzoic acid) are xenobiosis belonging to endocrine disruptors and commonly used as a preservative in cosmetics, food, pharmaceutical, and personal care products. Their wide use is leading to their appearance in water and wastewater in the range from ng/L to mg/L. In fact, the toxicity of benzylparaben is comparable to bisphenol A. Therefore, it is important to find not only effective but also ecofriendly methods for their removal from aqueous environment since the traditional wastewater treatment approaches are ineffective. Herein, for the first time, such extended comparison of several radical-driven technologies for paraben mixture degradation is presented. The detailed evaluation included (1) comparison of ozone and hydroxyl peroxide processes; (2) comparison of catalytic and photocatalytic processes (including photocatalytic ozonation); (3) characterisation of catalysts using SEM, XRD, DRS, XPS techniques and BET isotherm; (4) mineralisation, biodegradability and toxicity assessment; and (5) cost assessment. O3, H2O2/Fe2+, H2O2/UVC, O3/H2O2, O3/UVA, O3/H2O2/UVA, UVA/catalyst, O3/catalyst and O3/UVA/catalyst were selected from advanced oxidation processes to degrade parabens as well as to decrease its toxicity towards Aliivibrio fischeri, Corbicula fluminea and Lepidium sativum. Research was focused on the photocatalytic process involving visible light (UVA and natural sunlight) and TiO2 catalysts modified by different metals (Ag, Pt, Pd, Au). Photocatalytic oxidation showed the lowest efficiency, while in combining ozone with catalysis and photocatalysis process, degradation efficiency and toxicity removal were improved. Photocatalytic ozonation slightly improved degradation efficiency but appreciably decreased transferred ozone dose (TOD). Results indicate that the degradation pathway is different, or different transformation products (TPs) could be formed, despite that the hydroxyl radicals are the main oxidant. Graphical abstract.

Study of the influence of the matrix characteristics over the photocatalytic ozonation of parabens using Ag-TiO2.

Parabens are widely used as antimicrobial and preservative in pharmaceutical and personal products. Their presence has been detected in rivers and wastewater treatment plants. Photocatalytic ozonation process using a low amount of 0.1 wt% Ag-TiO2 proved to be efficient on the degradation of a mixture of five parabens using a low transferred ozone dose (TOD). The pH effect was analyzed under acidic and neutral conditions. Also, the effect of hydroxyl radical scavenger on parabens degradation and on by-products formation was discussed. Hydroxyl radical present a significant role over parabens degradation and also on by-products formation. The reaction mechanism was analyzed using municipal wastewater as a matrix to infer about the behavior of the process at actual conditions. Municipal wastewater as a matrix clearly enhanced the parabens degradation when compared with the case where ultrapure water was used. In fact, the TOD required for total parabens degradation is lowered 10-20 mg/L of TOD. Therefore, to understand the main responsible species for this improvement, the effects of several ions naturally present in wastewater (HCO3-, Cl- and SO42-) were tested. According to the results it seems that sulfate radical improves the process, while chloride and bicarbonate radicals decrease the process efficiency. In terms of toxicity the luminescence inhibition for Vibrio fischeri was analyzed. The inhibition significantly decreased for treated spiked municipal wastewater.

Biofiltration using C. fluminea for E.coli removal from water: Comparison with ozonation and photocatalytic oxidation.

Corbicula fluminea, an Asian clam, is one of the worst invasive species in Europe that can survive in very adverse environmental conditions. Despite its negative impacts, the species also has the capacity to bioaccumulate heavy metals, contaminants and can be exploited for wastewater treatment purposes. The capacity of the Asian clam to remove Escherichia coli, used as fecal contamination indicator, was analyzed. Conventional wastewater treatment plants are not suitable to remove bacteria, thus resulting in treated municipal wastewater with high bacterial loads. E. coli clearance rate was analyzed as function of the number of clams. The bivalves can remove bacteria until concentrations below the detection limit in about 6 h. The adsorption on the clam shells' and bioaccumulation on the soft tissues were also analyzed. The depuration of clams along 48 h were analyzed revealing that no bacteria was detected in the water. Thus, these results suggest that Asian clam can bioprocess E. coli. On the other hand, results obtained by this methodology were compared with ozonation and photocatalytic oxidation using TiO2, Ag, Au, Pd-TiO2. In all treatments it was possible to achieve concentrations of E. coli below the detection limit. However, photocatalytic oxidation demands about 4700 folds more energy than ozonation, besides the costs associated with catalysts. Comparing complexity of ozonation with biofiltration, this study suggests that application of biofiltration using C. fluminea can be a suitable solution to minimize the presence of bacteria in wastewater, reducing environmental and economic impacts.

Paraben degradation using catalytic ozonation over volcanic rocks.

Parabens are widely used as antimicrobial and preservatives in pharmaceutical and personal care products and are continuously reaching the water streams. Conventional wastewater treatments are proven inefficient on the removal of this kind of contaminants from wastewater. Therefore, catalytic ozonation appears as a suitable option, due to the oxidant power of ozone and its high capacity of hydroxyl radical generation in the presence of a suitable catalyst. The main drawback of catalytic ozonation is related with the choice of stable and active catalysts at low cost. On this way, two volcanic rocks were tested to enhance the removal of a mixture of parabens by ozonation, improving their degradation. Indeed, catalytic ozonation with volcanic rock allowed total paraben degradation using a transferred ozone dose (TOD) of 55 mg/L which corresponds to a reduction of about threefold the amount of TOD comparatively with single ozonation (170 mg/L of TOD). Due to the presence of semiconductors on volcanic rock composition, the effect of UVA irradiation on paraben degradation was analyzed. The neutral and basic conditions enhanced catalytic ozonation comparatively to acid conditions. Higher pH values allowed a total methylparaben degradation with 35 mg O3/L, whereas for low pH values, 55 mg O3/L was required. The use of a radical scavenger proven that hydroxyl radicals are the main responsible for paraben degradation with catalytic ozonation. This was confirmed through the analysis of the by-products, where 4-hydroxybenzoic acid, 3,4-dihydroxybenzoic acid (3,4-diHBA), 2,4-dihydroxybenzoic acid, and hydroquinone were quantified.

Photocatalytic ozonation using doped TiO2 catalysts for the removal of parabens in water.

Conventional wastewater treatments are inefficient for the removal of parabens. The aim of this study was finding a suitable solution using ozone and UVA irradiation combined with TiO2 catalysts doped with different noble metals (Ag, Pt, Pd, Au). Photocatalytic ozonation required lower amounts of ozone for higher efficiency on the removal of parabens, chemical oxygen demand (COD) and total organic carbon (TOC). The best catalyst for the initial contaminants degradation was 0.5% Ag-TiO2 leading to total parabens removal using 46mgO3/L. Due to the relative low mineralization achieved, the toxicity of the treated solutions was still compared with the initial one over several species (Vibrio fischeri, Lepidium sativum and Corbicula fluminea). All the treatments applied led to a clear decrease on the toxicity compared with initial mixture of parabens. From an economical point of view, it was concluded that the presence of UVA irradiation increased the energy consumption compared with catalytic ozonation with these catalysts but it can decrease the time of reaction. From the by-products analysis, it was concluded that hydroxylation appears to be the most significant reaction pathway and the main responsible for parabens degradation.

[Simple methods for estimating the concentration of toxic pollutants inside buildings]. / Métodos expeditos de estimativa da concentração de poluentes gasosos no interior de edifícios.

This paper presents simple methods for determining the concentration of toxic substances inside buildings, due to immediate release. Some case stu- dies are also presented, showing that these methods could go towards solving typical problems involved in building ventilation, such as the quantification of the number of air renovations necessary to exhaust toxic gases from inside buildings or to avoid the contamination by toxic gases coming from outside.

Evaluation of compliance with national legislation on emissions in Portugal.

More than 13 years after publication of the first air quality laws in Portugal and more than 10 years after the publication of the respective emission limits, it seems appropriate to analyze the degree of compliance by the Portuguese manufacturing industry. Using the data from emission measurements made regularly by the Instituto de Soldadura e Qualidade, the only officially accredited laboratory according to standard ISO 17025, I analyzed a set of approximately 400 sources in terms of compliance with the emission limits regarding total suspended particulates, sulfur dioxide, nitrogen oxides, and volatile organic compounds. I evaluated compliance through a nondimensional parameter and plotted it versus the emission flow rate to derive conclusions: the results indicate that emission limits are generally met regarding sulfur dioxide and nitrogen oxides but not for the other pollutants considered in this study. However, noncompliance occurs mainly for very low emission flow rates, which suggests some alterations in the emission limits, which are being revised at the moment. These alterations will include the exemption of measurements in minor sources.

Diagnostic study of critical circuits of the Kraft pulp production process considering the environmental aspects.

This paper describes systematic work undertaken in the field of atmospheric emissions from Portuguese Kraft pulp mills. The study led to the determination of emission factors from stationary sources, which proved to be an important tool for assessing the need for investment in air pollution abatement equipment, specifically for malodorous gases.