Nylon recovery from carpet waste through pyrolysis under the presence of zinc oxide and the roll-milling treatment

Recycling of carpet waste is not extensively carried out because of its complex combination of materials. A representative type of carpet consists of three layers: nylon fibers, adhesives, and backing materials made of poly(vinyl chloride), PVC. Thermal treatment of carpet waste, thus, leads to the emission of hazardous chlorinated compounds. In the present work, we have employed the one-directional thermal treatment of the backing materials under the presence of zinc oxide, which promotes the thermal degradation of PVC. Nylon fibers could be effectively recovered by the consequent milling treatment from the brittle backing materials. The influence of process parameters, such as pyrolysis temperature and reaction time, on the separation efficiency is discussed.     

Experimental testing of an annular denuder and filter system to measure gas–particle partitioning of semivolatile bifunctional carbonyls in the atmosphere

An annular denuder and filter-pack system was tested in combination with the use of the in-tube and on-fiber O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride (PFBHA)-derivatization technique to simultaneously sample and measure gaseous and particulate concentrations of semivolatile bifunctional carbonyl compounds in the atmosphere. Ozone was denuded from the sampling air to avoid oxidation and PFBHA was used as the sorbent by coating the sampling denuders and impregnating the filters. The collection efficiency of the system was evaluated under different conditions in photochemical smog chamber experiments and in field samplings of urban and suburban atmospheres. The effects of concentration level, temperature, and humidity on the collection efficiency were assessed. The system showed average collection efficiencies in one denuder from 81% for pyruvic acid and 82% for glyoxylic acid to 87% for hydroxyacetone and dihydroxyacetone. The capacity of the filters to collect the gaseous fraction that cannot be collected in the denuders was also evaluated, and the system allows a correction for this artifact. The application of this method to chamber experiments and field samplings offers an easy-to-apply technique with good results that can be used to evaluate the partition mechanisms of these compounds in the atmosphere.     

Photochemical and photocatalytic degradation of gaseous toluene using short-wavelength UV irradiation with TiO2 catalyst: comparison of three UV sources

The feasibility of the use of short-wavelength UV (254+185 nm) irradiation and TiO2 catalyst for photodegradation of gaseous toluene was evaluated. It was clear that the use of TiO2 under 254+185 nm light irradiation significantly enhanced the photodegradation of toluene relative to UV alone, owed to the combined effect of photochemical oxidation in the gas phase and photocatalytic oxidation on TiO2. The photodegradation with 254+185 nm light irradiation was compared with other UV wavelengths (365 nm (black light blue lamp) and 254 nm (germicidal UV lamp)). The highest conversion and mineralization were obtained with the 254+185 nm light. Moreover, high conversions were achieved even at high initial concentrations of toluene. Catalyst deactivation was also prevented with the 254+185 nm light. Regeneration experiments with the deactivated catalyst under different conditions revealed that reactive oxygen species played an important role in preventing catalyst deactivation by decomposing effectively the less reactive carbon deposits on the TiO2 catalyst. Simultaneous elimination of photogenerated excess ozone and residual organic compounds was accomplished by using a MnO2 ozone-decomposition catalyst to form reactive species for destruction of the organic compounds.     

Polychlorinated biphenyl (118) activates osteoclasts and induces bone resorption in goldfish

To analyze the effect of polychlorinated biphenyl (PCB) 118 on fish bone metabolism, we examined osteoclastic and osteoblastic activities, as well as plasma calcium levels, in the scales of PCB (118)-injected goldfish. In addition, effect of PCB (118) on osteoclasts and osteoblasts was investigated in vitro. Immature goldfish, in which the endogenous effects of sex steroids are negligible, were used. PCB (118) was solubilized in dimethyl sulfoxide at a concentration of 10 ppm. At 1 and 2 days after PCB (118) injection (100 ng/g body weight), both osteoclastic and osteoblastic activities, and plasma calcium levels were measured. In an in vitro study, then, both osteoclastic and osteoblastic activities as well as each marker mRNA expression were examined. At 2 days, scale osteoclastic activity in PCB (118)-injected goldfish increased significantly, while osteoblastic activity did not change significantly. Corresponding to osteoclastic activity, plasma calcium levels increased significantly at 2 days after PCB (118) administration. Osteoclastic activation also occurred in the marker enzyme activities and mRNA expressions in vitro. Thus, we conclude that PCB (118) disrupts bone metabolism in goldfish both in vivo and in vitro experiments.     

Relationship between growth rate and egg production in the copepod Acartia clausi hudsonica

Egg production by Acartia clausi hudsonica ceases at low concentrations of Isochrysis galbana as food and at high levels reaches a maximum that increases with temperatures in the natural range. This increase parallels the rate of production of fecal pellets. Females without males can produce about 400 eggs before entering a generally short postreproductive period. Weight increments between copepodite stages are exponential and, assuming isochronal durations of stages and that development time of older stages is the same mutiple of embryonic duration at all temperatures, a temperature-dependent rate is estimated for pre-adult growth. We demonstrate that this growth rate also predicts the observed maximal rate of egg production by the nongrowing adult females. Published data for other copepod species (except Pseudocalanus) are inadequate for wider testing of this hypothesis, but available data do suggest that no such simple rule governs total output of eggs by females of different species.     

Development of Mn recovery process from waste dry cell batteries

High-purity Mn is necessary for high strength steel production. However, the availability of metal Mn is limited to a few countries. Therefore, as an alternative to direct purchasing of metal Mn, a process for Mn recovery was investigated. Waste dry cell batteries are considered to be one of the most feasible Mn sources. We have developed a high efficiency chemical separation system. This system consists of a three-phase chemical treatment. In the first phase, the metal components of the waste dry cell batteries were dissolved by acid, along with a reducing agent. Afterward, the undissolved carbon particles were separated by filtration. In the second phase, the dissolved Mn was selectively precipitated as manganese oxide by O₃ oxidation. Then, the precipitated manganese oxide was separated from the other metal components by filtration. Finally, in the third phase, the manganese oxide was reduced to high-purity Mn using an electric furnace.     

Removal of mercury using processes involving sulfuric acid during zinc production in an imperial smelting process (ISP) plant

Journal of Material Cycles and Waste Management - Mercury emissions from non-ferrous metal industries are a major environmental concern. Because of the large differences in mercury emission factors...     

Influence of ozone, relative humidity, and flow rate on the deposition and oxidation of sulfur dioxide on yellow sand

To evaluate the influences of O₃, relative humidity (RH), and flow rate on the reaction between yellow sand and SO₂, the SO₂ deposition velocity and the oxidation state of sulfur were investigated by means of exposure experiments in a cylindrical flow reactor. Early in the reaction, the deposition velocity was not influenced by the RH or the presence of O₃; as the reaction progressed, however, the deposition velocity increased in the presence of O₃ and at high humidity. The oxidation of sulfur from S(IV) to S(VI) was also enhanced under these conditions. The amount of sulfur oxidation was positively correlated with the amount of deposited O₃. Furthermore, the SO₂ deposition velocity increased with increasing flow rate. However, changes in the flow rate had no noticeable effect on the amount of SO₂ oxidation.     

Oceanic squid do fly

Using powerful jet propulsion, some squid species are able to exit the water and become airborne; this is a common behavior seen throughout the world’s oceans. However, direct scientific observation is rare, with most studies relying on anecdotal evidence and limited photographic documentation. Here, we examine the flying behavior of young oceanic squid (Ommastrephidae) observed in sequential photographs taken in the Northwest Pacific (35^o34.0′N, 146^o19.3′E) on July 25, 2011. We define four phases in the flight process: launching, jetting, gliding and diving. During flight, squid actively change their aerial posture and attitude depending on the flight phase and their distance from the water. The present study demonstrated that flight of squid is not simple gliding after incidental exit from the water, but involves jet propulsion, generation of lift force and control of different body postures in different flight phases, which have evolved to enhance escape from predators.