Characterization of Volatile Organic Compounds (VOC) in wet-white and metal-free leathers

Content: As it is known in the tanning sector, in recent times, the so-called wet-white and/or metal-free concepts have had a certain increase. For example, in the automotive sector, the wet-white tanning system, carried out with glutaraldehyde and tannins, has been widely diffused. In fact, car manufacturers offer, for interior furnishings, leather not only for high-end cars but increasingly also in the lower segments. The components on which the leather upholstery is applied are mainly steering wheel, seats, dashboard and panels. Therefore, the use of leather also in this context must be able to meet both the aesthetic/performance criteria and the environmental ones; environmental criteria should also consider the air quality of the interior of a motor vehicle. In practice, the interior furniture consisting of finished leather must be able to release a few volatile substances and, at the same time, provide a typical smell of leather. Considering, therefore, the diffusion of alternative chrome tanning systems for the different uses, in this work, wet-white (glutaraldehyde and tannins) will be investigated, both from the point of view of the performance characteristics and from the ecotoxicological ones. and leathers deriving from the latest generation of metal-free tanning. For the characterization of Volatile Organic Compounds (VOC) the GC-MS will be used coupled with the 'Purge and Trap' technique with the aim of obtaining information on the new substances used in the wetwhite / metal free production process and then avoiding undesired effects during use (eg bad smell, SVHC substances, etc.) Take-Away: metal-free automotive VO

Use of chitosan for chromium removal from exhausted tanning baths.

A novel approach, based on chitosan heavy-metal sequestrating ability, is proposed for chromium(III) removal from spent tanning liquor. Experimental results, obtained at lab-scale using real wastewater, are presented and discussed. Resulting efficiencies are extremely high, and strongly dependent on chitosan dose and pH value. Comparative analyses with other polysaccharides is also carried out showing that amine groups are more efficient than carboxyl and sulphate ones. Chromium recovery from sorption complexes and chitosan regeneration is finally proposed to optimize the whole process

Improving electrical conductivity of leather surface: a new technology versus industrial applications

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Enhanced Thermal Treatment of Tannery Sewage Sludge

Thermal conversion of sewage sludge presents several advantages, such as the reduction of mass and volume of solid waste and energy recovery from the organic sludge fraction, resulting in lower disposal costs with respect to landfilling. In this work, the combustion behaviour of a dried tannery sewage sludge was compared in the absence and in the presence of a catalyst, investigating the role of catalyst loading. The catalyst mixed with the dried sludge improves either the selectivity of the sludge combustion process, reducing the emission of cyclic and aromatic substances, either the combustion peak temperature, yielding a higher oxidation rate of the sludge organic fraction. By adding the catalysts in the step of sludge formation, i.e. immediately after the addition of flocculant into the coagulation-flocculation step of tannery wastewater, the combustion peak of the sludge organic fraction occurred at about 300 K lower than in the absence of catalyst (about 798 K), pointing out to a significant improvement of the oxidation process due to the catalytic material

A thermogravimetric study on tannery sewage sludges

Two different tannery sewage sludges (Sludge 1 and Sludge 2) have been characterized by thermal anal. coupled with mass spectrometry of evolved gases (TG-DSC-MS), inductively coupled plasma-at. emission spectrometry (ICP-AES), Gas chromatog. - mass spectrometry (GC-MS), Purge and trap GC-MS. Four main temp. ranges of wt. loss were individually examd. in air flow TG-DSC-MS expts. on Sludge 1. The first, below 200C, coupled to an endothermic signal, is related to water release. Between 200 and 350C, an exothermic signal accompanies the loss of sulfate as evolved SO2 org. substances, aroms. and satd. cyclic compds. In the latter range, development of CO2 was also obsd., this becomes prevalent in the range 350-600C. From 600 to 700C carbon dioxide from carbonate decompn. was obsd. In Sludge 2, three main temp. ranges of wt. loss are present, below 150C, between 150 and 350C and from 350 to 600C, attributed, resp., to water, sulfate, CO2 plus arom. and carbonyl compd. releases. A larger amt. of Cr and Al was found by ICP-AES in Sludge 2. The differences between the samples evidence the influence of the compn. of the parent wastewater and of the depuration process. The influence of additives on combustion profiles has been also evaluated. Catalyst addn. to the sludge results to reduce the emission of cyclic and arom. substances, to lower temp. and to increase the oxidn. rate of org. fraction combustion

Characterization of Volatile Organic Compounds (VOC) in wet-white and metal-free leathers

Content: As it is known in the tanning sector, in recent times, the so-called wet-white and/or metal-free concepts have had a certain increase. For example, in the automotive sector, the wet-white tanning system, carried out with glutaraldehyde and tannins, has been widely diffused. In fact, car manufacturers offer, for interior furnishings, leather not only for high-end cars but increasingly also in the lower segments. The components on which the leather upholstery is applied are mainly steering wheel, seats, dashboard and panels. Therefore, the use of leather also in this context must be able to meet both the aesthetic/performance criteria and the environmental ones; environmental criteria should also consider the air quality of the interior of a motor vehicle. In practice, the interior furniture consisting of finished leather must be able to release a few volatile substances and, at the same time, provide a typical smell of leather. Considering, therefore, the diffusion of alternative chrome tanning systems for the different uses, in this work, wet-white (glutaraldehyde and tannins) will be investigated, both from the point of view of the performance characteristics and from the ecotoxicological ones. and leathers deriving from the latest generation of metal-free tanning. For the characterization of Volatile Organic Compounds (VOC) the GC-MS will be used coupled with the 'Purge and Trap' technique with the aim of obtaining information on the new substances used in the wetwhite / metal free production process and then avoiding undesired effects during use (eg bad smell, SVHC substances, etc.) Take-Away: metal-free automotive VO

Characterization of Volatile Organic Compounds (VOC) in wet-white and metal-free leathers

Content: As it is known in the tanning sector, in recent times, the so-called wet-white and/or metal-free concepts have had a certain increase. For example, in the automotive sector, the wet-white tanning system, carried out with glutaraldehyde and tannins, has been widely diffused. In fact, car manufacturers offer, for interior furnishings, leather not only for high-end cars but increasingly also in the lower segments. The components on which the leather upholstery is applied are mainly steering wheel, seats, dashboard and panels. Therefore, the use of leather also in this context must be able to meet both the aesthetic/performance criteria and the environmental ones; environmental criteria should also consider the air quality of the interior of a motor vehicle. In practice, the interior furniture consisting of finished leather must be able to release a few volatile substances and, at the same time, provide a typical smell of leather. Considering, therefore, the diffusion of alternative chrome tanning systems for the different uses, in this work, wet-white (glutaraldehyde and tannins) will be investigated, both from the point of view of the performance characteristics and from the ecotoxicological ones. and leathers deriving from the latest generation of metal-free tanning. For the characterization of Volatile Organic Compounds (VOC) the GC-MS will be used coupled with the 'Purge and Trap' technique with the aim of obtaining information on the new substances used in the wetwhite / metal free production process and then avoiding undesired effects during use (eg bad smell, SVHC substances, etc.) Take-Away: metal-free automotive VO