Tetra-hydroxymethyl phosphonium chloride （THPC） has been considered as an important chrome-free tanning agent. To understand the THPC tanning mechanism, the structure, charge distribution, activity and tanning abili...Tetra-hydroxymethyl phosphonium chloride （THPC） has been considered as an important chrome-free tanning agent. To understand the THPC tanning mechanism, the structure, charge distribution, activity and tanning ability of each phosphorous compound in THPC tanning system were studied, by ^31p NMR, FT-IR spectroscopy, differential scanning calorimetry （DSC） and computational chemistry method, etc. When pH raised to 6.0, the decomposition of THPC would take place, which results in a production of free formaldehyde, tri-hydroxymethyl phosphonium （TrHP） and tri-hydroxymethyl phosphine oxide （TrHPO）. At pH 9.0, THPC will be converted completely to TrHP and most TrHP is further oxidized into TrHPO. It is possible that, in reaction of phosphorous compounds and collagens, both P-C and C-O bonds would break simultaneously or individually. From molecular charge distribution and bond polar properties, it is deduced that, if P-C bonds break, the activity is in order of TrHPO 〉 THPC 〉 TrHE whereas if C--O bonds break, the order is TrHP 〉 THPC 〉 TrHPO. It is more possible that P--C bonds will break in reaction with collagen, and TrHPO may be more active in the THPC tanning system. The results of tanning and DSC also prove the above conclusion. Furthermore, the fact that the shrinkage temperature of THPC tanned leather was below 70℃ when basified to pH 5.0 or lower suggests that the hydroxymethyl groups of THPC and TrHP are less possible to combine directly with amino groups of collagen.展开更多
Nitrosonaphthol dyes and other corresponding analogues were synthesised from 1-Naphthol. The dyes were applied onto chrome and vegetable tanned leather upon characterization. The results indicate that the dye bath exh...Nitrosonaphthol dyes and other corresponding analogues were synthesised from 1-Naphthol. The dyes were applied onto chrome and vegetable tanned leather upon characterization. The results indicate that the dye bath exhaustion was better on chrome tanned leather than on vegetable tanned leather. This may be attributed to the chelating effect of chrome on leather and the higher temperature of dyeing the chrome tanned leather compared with the vegetable tanned leather. The fastness properties of the dyes of washing ranging from (3 - 5), perspiration on acid (4 - 5), alkaline (4 - 5) and light (4 - 7) were impressive on both vegetable and chrome tanned leather respectively.展开更多
Collagen powder hydrolysates were reacted with a solution of commercial mimosa bark tannin extract.The mixture was prepared at ambient temperature and prepared at 80°C to determine what reactions,if any,did occur...Collagen powder hydrolysates were reacted with a solution of commercial mimosa bark tannin extract.The mixture was prepared at ambient temperature and prepared at 80°C to determine what reactions,if any,did occur between the collagen protein through its amino acids and the polyphenolic condensed tannin.The reaction products obtained were analyzed by matrix assisted laser desorption ionization time-of-flight(MALDI ToF)mass spectrometry.Reactions between the two materials did appear to occur,with the formation of a relatively small proportion of covalent and ionic linkages at ambient temperature but a considerable proportion of covalent linkages tannin-protein amino acids and the disappearance of ionic bonds.The linkages between the two materials appeared to be by amination of the phenolic–OHs of the tannin by the amino groups of the non-skeletal side chains of arginine,and by esterification by the–COOH groups of glutamic and aspartic acid of the aliphatic alcohol-OH on the C3 site of the flavonoid units heterocycle of the tannin.The proportion of covalent linkages increases markedly and predominate with increasing temperatures.This tightening of the tannin-protein covalent network formed may be an additional contributing factor both to leather wear resistance and performance as well to leather shrinking when this is subjected to excessive temperatures.展开更多
A category of chromium (Cr)-containing fertilizers is represented by the fertilizers deriving from byproducts of tanning process. Their use is widespread because of their good agronomic response due to the high conten...A category of chromium (Cr)-containing fertilizers is represented by the fertilizers deriving from byproducts of tanning process. Their use is widespread because of their good agronomic response due to the high content of slow release or- ganic nitrogen (N) and carbon (C). They do not represent an environmental hazard because only the non-toxic form of Cr(III) is present. Productive processes may involve chemical, enzymatic or thermal hydrolysis. The final product is characterized by different contents of peptides and free amino acids depending on the type of hydrolysis. Legislation concerning Cr-containing fertilizers is controversial because often do not consider any scientific evidences;nevertheless, the European Union, the United States and countries as Italy, do not set the restriction to Cr(III) and generally only the presence of the toxic form, Cr(VI), is limited. Depending on its two main oxidation forms, Cr issue has been studied for many years. Several authors confirmed that Cr(VI) is carcinogenic, while Cr(III) is an essential trace element in human and animal diet. In soil Cr(III) has low mobility, whereas Cr(VI) is highly water soluble. However Cr(VI) in soil is quickly reduced to Cr(III);on the contrary oxidation of Cr(III) to Cr(VI) is rarely possible because particular conditions must occur. Only a very small fraction of Cr in soil is available to plant uptake and its translocation in edible parts is limited because it is immobilized in roots as Cr(III). Therefore risks of environmental pollution using these fertilizers are negligible;on the contrary they have positive environmental and agronomical effects. The aim of this review is to deal with the category of the organic fertilizers containing Cr derived from tannery processes focusing on its chemical, productive, legislative, environmental and agronomical aspects. Special attention is given to the ambiguous issue of Cr briefly summarizing the most important studies of the last forty years.展开更多
The leather manufacturing is traditionally responsible for high environmental pollution. Tannery effluent contains, indeed, large amounts of lime sludge, sulfides, acids, toxic metals salts, in particular chromium sal...The leather manufacturing is traditionally responsible for high environmental pollution. Tannery effluent contains, indeed, large amounts of lime sludge, sulfides, acids, toxic metals salts, in particular chromium salts, which are toxic, non-biodegradable and hardly disposable. For this reason, great research efforts are addressed to establish a significantly eco-sustainable and convenient business for companies and to produce high quality leather products. The replacement of current commercial chemical and toxic products with innovative natural/naturalized products and technologies in some crucial phases of the tanning cycle （mainly bating and defatting）, can induce an eco-friendly reduction of the needed chromium amount. Leather samples, treated with innovative bating and defatting products and tanned by several different Cr contents, were characterized by SEM-EDS （Scanning Electron Microscopy equipped with Energy Dispersive X-Ray Spectroscopy） and TGA （Thermogravimetric Analysis）. SEM-EDS was used to observe the surface and cross-section morphology and to provide a semi-quantitative elemental analysis, while TGA to evaluate the thermal stability and decomposition phases. The compatibility of the innovative products was demonstrated and the environmental impact of the process, performed by the effluents characterization, was effectively improved as a result of a 20% Cr lowering. The use of innovative products and the chromium reduction did not affect the thermal stability, leather morphology and not involve significant differences in the composition.展开更多
The radical polymerization of maleic anhydride（MA）,styrene（ST）with the vinyl groups introduced onto the surface of the nano-sized silica via solution polymerization method was developed.The methacryloxypropyl nano...The radical polymerization of maleic anhydride（MA）,styrene（ST）with the vinyl groups introduced onto the surface of the nano-sized silica via solution polymerization method was developed.The methacryloxypropyl nano-sized silica（MPNS）was used as macromonomer and polymerized with maleic anhydride and styrene by initiating with BPO in toluene.The structure and properties of MPNS/SMA nano-composite were characterized by FT-IR spectra and TEM.Meanwhile,it was applied as tanning agent compared with the traditional styrene-maleic anhydride copolymer in leather.It was found that the applied leather had better quality characteristics with the addition of the nano-sized silica.展开更多
Traditional chrome tanning technology is still widely used today. In this technology, chrome shaving as well as chrome contained effluent in tanning and retanning processes is a big issue in the industry. Wet white ta...Traditional chrome tanning technology is still widely used today. In this technology, chrome shaving as well as chrome contained effluent in tanning and retanning processes is a big issue in the industry. Wet white tanning technology has been gaining in importance in recent years, but in general, the comprehensive performance of chrome-free tanned leather is not comparable with that of chrome tanned leather. In the present work, chrome-free tanning and chrome tanning are combined in a reversed procedure, which produces leather with chrome tanned leather quality without chrome tanned leather waste problems. In this procedure, a special amphoteric organic compound, no pickle, no salt chrome-free tanning agent TWT was used to tan delimed hides （no pickle） making wet white with shrinking temperature at 80-85 ~C. Then, new method called reversed tanning further process the wet white into chrome-tanned crust. In this reversed method, retanning, fatliquoring and coloring processes were carried out before chrome tanning. This technology eliminates chrome waste issue in tanning, shaving, post tanning processes. The chrome contained effluent is only concentrated in the last chrome tanning process. The leather made with this technology has complete conventional chrome-tanned leather quality. In this way, chrome leather quality without chrome waste problems was achieved. So, it is a new clean tanning technology.展开更多
基金the National Basic Research Program (2007CB616909)Startup Foundation of Applied Chemistry of the Key Discipline of Zhejiang University of Technology and Zhejiang Provincial Science and Technology Plan (2006C21107)
文摘Tetra-hydroxymethyl phosphonium chloride （THPC） has been considered as an important chrome-free tanning agent. To understand the THPC tanning mechanism, the structure, charge distribution, activity and tanning ability of each phosphorous compound in THPC tanning system were studied, by ^31p NMR, FT-IR spectroscopy, differential scanning calorimetry （DSC） and computational chemistry method, etc. When pH raised to 6.0, the decomposition of THPC would take place, which results in a production of free formaldehyde, tri-hydroxymethyl phosphonium （TrHP） and tri-hydroxymethyl phosphine oxide （TrHPO）. At pH 9.0, THPC will be converted completely to TrHP and most TrHP is further oxidized into TrHPO. It is possible that, in reaction of phosphorous compounds and collagens, both P-C and C-O bonds would break simultaneously or individually. From molecular charge distribution and bond polar properties, it is deduced that, if P-C bonds break, the activity is in order of TrHPO 〉 THPC 〉 TrHE whereas if C--O bonds break, the order is TrHP 〉 THPC 〉 TrHPO. It is more possible that P--C bonds will break in reaction with collagen, and TrHPO may be more active in the THPC tanning system. The results of tanning and DSC also prove the above conclusion. Furthermore, the fact that the shrinkage temperature of THPC tanned leather was below 70℃ when basified to pH 5.0 or lower suggests that the hydroxymethyl groups of THPC and TrHP are less possible to combine directly with amino groups of collagen.
文摘Nitrosonaphthol dyes and other corresponding analogues were synthesised from 1-Naphthol. The dyes were applied onto chrome and vegetable tanned leather upon characterization. The results indicate that the dye bath exhaustion was better on chrome tanned leather than on vegetable tanned leather. This may be attributed to the chelating effect of chrome on leather and the higher temperature of dyeing the chrome tanned leather compared with the vegetable tanned leather. The fastness properties of the dyes of washing ranging from (3 - 5), perspiration on acid (4 - 5), alkaline (4 - 5) and light (4 - 7) were impressive on both vegetable and chrome tanned leather respectively.
文摘Collagen powder hydrolysates were reacted with a solution of commercial mimosa bark tannin extract.The mixture was prepared at ambient temperature and prepared at 80°C to determine what reactions,if any,did occur between the collagen protein through its amino acids and the polyphenolic condensed tannin.The reaction products obtained were analyzed by matrix assisted laser desorption ionization time-of-flight(MALDI ToF)mass spectrometry.Reactions between the two materials did appear to occur,with the formation of a relatively small proportion of covalent and ionic linkages at ambient temperature but a considerable proportion of covalent linkages tannin-protein amino acids and the disappearance of ionic bonds.The linkages between the two materials appeared to be by amination of the phenolic–OHs of the tannin by the amino groups of the non-skeletal side chains of arginine,and by esterification by the–COOH groups of glutamic and aspartic acid of the aliphatic alcohol-OH on the C3 site of the flavonoid units heterocycle of the tannin.The proportion of covalent linkages increases markedly and predominate with increasing temperatures.This tightening of the tannin-protein covalent network formed may be an additional contributing factor both to leather wear resistance and performance as well to leather shrinking when this is subjected to excessive temperatures.
文摘A category of chromium (Cr)-containing fertilizers is represented by the fertilizers deriving from byproducts of tanning process. Their use is widespread because of their good agronomic response due to the high content of slow release or- ganic nitrogen (N) and carbon (C). They do not represent an environmental hazard because only the non-toxic form of Cr(III) is present. Productive processes may involve chemical, enzymatic or thermal hydrolysis. The final product is characterized by different contents of peptides and free amino acids depending on the type of hydrolysis. Legislation concerning Cr-containing fertilizers is controversial because often do not consider any scientific evidences;nevertheless, the European Union, the United States and countries as Italy, do not set the restriction to Cr(III) and generally only the presence of the toxic form, Cr(VI), is limited. Depending on its two main oxidation forms, Cr issue has been studied for many years. Several authors confirmed that Cr(VI) is carcinogenic, while Cr(III) is an essential trace element in human and animal diet. In soil Cr(III) has low mobility, whereas Cr(VI) is highly water soluble. However Cr(VI) in soil is quickly reduced to Cr(III);on the contrary oxidation of Cr(III) to Cr(VI) is rarely possible because particular conditions must occur. Only a very small fraction of Cr in soil is available to plant uptake and its translocation in edible parts is limited because it is immobilized in roots as Cr(III). Therefore risks of environmental pollution using these fertilizers are negligible;on the contrary they have positive environmental and agronomical effects. The aim of this review is to deal with the category of the organic fertilizers containing Cr derived from tannery processes focusing on its chemical, productive, legislative, environmental and agronomical aspects. Special attention is given to the ambiguous issue of Cr briefly summarizing the most important studies of the last forty years.
文摘The leather manufacturing is traditionally responsible for high environmental pollution. Tannery effluent contains, indeed, large amounts of lime sludge, sulfides, acids, toxic metals salts, in particular chromium salts, which are toxic, non-biodegradable and hardly disposable. For this reason, great research efforts are addressed to establish a significantly eco-sustainable and convenient business for companies and to produce high quality leather products. The replacement of current commercial chemical and toxic products with innovative natural/naturalized products and technologies in some crucial phases of the tanning cycle （mainly bating and defatting）, can induce an eco-friendly reduction of the needed chromium amount. Leather samples, treated with innovative bating and defatting products and tanned by several different Cr contents, were characterized by SEM-EDS （Scanning Electron Microscopy equipped with Energy Dispersive X-Ray Spectroscopy） and TGA （Thermogravimetric Analysis）. SEM-EDS was used to observe the surface and cross-section morphology and to provide a semi-quantitative elemental analysis, while TGA to evaluate the thermal stability and decomposition phases. The compatibility of the innovative products was demonstrated and the environmental impact of the process, performed by the effluents characterization, was effectively improved as a result of a 20% Cr lowering. The use of innovative products and the chromium reduction did not affect the thermal stability, leather morphology and not involve significant differences in the composition.
文摘The radical polymerization of maleic anhydride（MA）,styrene（ST）with the vinyl groups introduced onto the surface of the nano-sized silica via solution polymerization method was developed.The methacryloxypropyl nano-sized silica（MPNS）was used as macromonomer and polymerized with maleic anhydride and styrene by initiating with BPO in toluene.The structure and properties of MPNS/SMA nano-composite were characterized by FT-IR spectra and TEM.Meanwhile,it was applied as tanning agent compared with the traditional styrene-maleic anhydride copolymer in leather.It was found that the applied leather had better quality characteristics with the addition of the nano-sized silica.
文摘Traditional chrome tanning technology is still widely used today. In this technology, chrome shaving as well as chrome contained effluent in tanning and retanning processes is a big issue in the industry. Wet white tanning technology has been gaining in importance in recent years, but in general, the comprehensive performance of chrome-free tanned leather is not comparable with that of chrome tanned leather. In the present work, chrome-free tanning and chrome tanning are combined in a reversed procedure, which produces leather with chrome tanned leather quality without chrome tanned leather waste problems. In this procedure, a special amphoteric organic compound, no pickle, no salt chrome-free tanning agent TWT was used to tan delimed hides （no pickle） making wet white with shrinking temperature at 80-85 ~C. Then, new method called reversed tanning further process the wet white into chrome-tanned crust. In this reversed method, retanning, fatliquoring and coloring processes were carried out before chrome tanning. This technology eliminates chrome waste issue in tanning, shaving, post tanning processes. The chrome contained effluent is only concentrated in the last chrome tanning process. The leather made with this technology has complete conventional chrome-tanned leather quality. In this way, chrome leather quality without chrome waste problems was achieved. So, it is a new clean tanning technology.
