Leaching behavior of metals from asphalt mixtures modified with crumb rubber from scrap tires.

There are concerns about the potential toxicity of bitumen and recycled materials such as reclaimed asphalt pavements from end-of-life roads and crumb rubber from scrap tires used in asphalt mixtures because they contain metals that may be released into the groundwater. This study investigated the potential metal leaching of laboratory-prepared asphalt mixtures modified with polymer coated rubber (PCR) with wet and dry technology, devulcanized rubber (DVR), compared to an unmodified control mixture and a blend modified with a synthetic polymer (SBS). The objectives were to i) quantify concentrations of metals released, ii) calculate the flux rate, the cumulative mass release, and the assessment ratio for each metal, iii) verify if the metals exceeded the EPA drinking water limit, and, finally, iv) assess the source of metals release. Zinc had the highest concentration among all metals and was present in eluates from all mixtures. The cumulative zinc concentration from DVR mixture was 41% and 34% higher than the control and SBS mixtures, respectively. For PCR wet, the cumulative zinc concentration was 9% higher than the control blend and 1% lower than the SBS mix. The assessment ratio indicated that all metal concentrations would not exceed the drinking water limit, except for zinc, for which further evaluations were required. The main source of zinc may derive from aggregates. This work showed that crumb rubber might not be the only source of metal leaching, and its use in asphalt pavements does not cause a metal leaching higher than other materials.

Cost analysis and environmental assessment of recycling paint sludge in asphalt pavements.

Paint sludge (PS) is a waste product coming from spray application of paints in automotive industry. For the first time, this work assessed the economic costs and environmental impacts connected to recycling PS in bituminous binders for asphalt pavement applications. Previous works have demonstrated that PS could be used as a replacement of up to 20% (w/w) of neat bitumen in the production of hot mixture asphalts (HMAs), without worsening the technical performances of pavements. The annual production of PS from Italian automotive plants (3000 t/year) could be accommodated in a paved area of 1.64 km2 that, when employed in local roads, with an average width of 5 m, corresponds to approximately 330 km. Costs for treating PS to be prepared for recycling resulted in 144 €/t raw PS. This cost was of the same order, or even less, of that required for PS incineration or disposal in a landfill for hazardous waste (250-300 €). The LCA analysis revealed that the production of HMAs by employing a binder that contains 20% (w/w) of PS, reduced the gross energy requirement (GER) and global warming potential (GWP) indexes by 15% and 39%, respectively, compared to an HMA produced with the traditional process.

Advances and challenges in the synthesis of highly oxidised natural phenols with antiviral, antioxidant and cytotoxic activities.

Polyphenols are a family of organic compounds characterized by a wide range of biological activities. Among natural polyphenols, the products derived from shikimic and polyketide biogenic pathways, such as lignans, neolignans, cardanols and flavonoids are of special interest owing to their powerful antioxidant, antitumoral, antimitotic, antiviral, cardiovascular and immunosuppressive activity. The biological activity of polyphenols can be finely tuned by the oxidation state of the molecule. Polyphenols are subject to oxidative metabolism in the cell by cytochrome p-450 dependent enzymes, mainly at reactive benzyl and aryl positions of the molecule, to yield highly oxidised derivatives, namely quinones, hydroquinones, semiquinones, catechols and others, whose biological activity can greatly differ from that of the parental compound. In fact, these derivatives are characterized by peculiar antitumoral, antioxidant and antiviral activities and show different chemical properties toward nucleophiles and electrophiles active sites in the cell. This behavior is dependent on the specific value of the redox potential in the cell. The low concentration of these metabolites in nature, and the difficulty to recover them from mammalian cells or fluids require novel procedures for their synthesis to collect adequate amounts of compounds for biological assays. On the other hand, only a few attentions has been devoted to design novel oxidative procedures for the synthesis of highly oxidised polyphenols characterized by higher biological activity. In this review, advances and challenges in the synthesis of natural and semi-synthetic highly oxidised polyphenols are reported focusing the attention in the recent years. Data on the antiviral, antioxidant and cytotoxic activities in vivo and in vitro systems for natural and semi-synthetic highly oxidised polyphenols are also reported, and the effect on the biological activity due to the introduction of one or more oxygen atoms in different reactive sites of the molecule, is discussed.

Synthesis of hydroxystilbenes and their derivatives via Heck reaction.

A group of differently substituted acetoxy- and methoxystilbenes were synthesised via Heck reaction. A comparison between the use--as coupling reagents--of iodobenzene derivatives and diazonium salts was performed. A successful microwave-assisted demethylation by pyridine hydrochloride of some methoxystilbenes was carried out.

An improved synthesis of resveratrol.

In this article we report an improved total synthesis of resveratrol, increasing the overall yield from 22 to 71%. The synthesis reported in our previous publication was made up of two fundamental steps: a Wittig reaction and a Heck coupling. Here we studied these steps separately to increase the individual yields. The yield of the Wittig reaction was increased up to 98%; however, we could not find better reaction conditions for the Heck coupling than those reported in the previous article.