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1.
Carbohydr Polym ; 304: 120511, 2023 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-36641159

RESUMO

The development of sustainable and eco-friendly leather industry requires green tanning agents because of unbounded chromium (easily converted into hazardous Cr-VI) in chrome tanned leather. In this study, a chrome-free tanning agent (OS-LDHs) was established by integrating layered double hydroxide (magnesium aluminum zirconium hydrotalcite, LDHs) with starch derivatives. A series of oxidized starch (OS) were prepared as masking agents for LDHs tanning process. Among them, the weight-average molecular weight (Mw) of 1685 g/mol could be reached, which will promise the well-distribution of OS. The SEM and EDS analysis confirmed the uniform penetration of OS-LDHs, avoiding accumulation on the surface of crust leather. Notably, leather tanned by OS-LDHs achieved shrinkage temperature of 66.7 °C, porosity of 75.51 % and tear strength of 66.7 N/mm. Not only the hydrogen bond but also the coordination between NH2, COOH in collagen and OS-2-LDHs improved the thermal stability of leather without destroying the collagen triple helix.


Assuntos
Amido , Curtume , Indústrias , Cromo/química , Colágeno/química
2.
Sci Total Environ ; 862: 160713, 2023 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-36509278

RESUMO

To get rid of the chrome pollution faced by the leather industry, we explored a novel engineering high-quality eco-leather technology based on the synergistic interactions between biomass-based aldehydes and Al(III). Firstly, dialdehyde xanthan gum (DXG) was prepared to covalently crosslink with the collagen fibers (CFs) via Schiff-base linkages under alkaline conditions, endowing the leather with a shrinkage temperature (Ts) of 80 °C and opening channels for the subsequent penetration of Al species (AL). Secondly, and for this latter purpose, the DXG-tanned leather was acidified to release part of the DXG from the leather according to the dynamic nature of the Schiff-base. Containing suitable oxygen-containing groups (OGs) with excellent complexation capabilities, the released DXG served as masking agents for AL, facilitating the penetration of AL into the inner CFs network for further complexation crosslinking. Consequently, a denser crosslinking network was constructed in the leather, and the crust leather exhibited higher Ts (82.2 °C), improved mechanical (tensile strength: 13.4 N/mm2, tear strength: 53.3 N/mm) and organoleptic properties than those of the DXG crust or AL crust leathers. This demonstrates that this synergistic covalence and complexation bridging strategy is a sustainable option to substitute highly restricted chrome tanning agent for eco-leather production.


Assuntos
Aldeídos , Síndrome de Fadiga Crônica , Humanos , Curtume , Biomassa , Poluição Ambiental
3.
Int J Mol Sci ; 23(21)2022 Nov 07.
Artigo em Inglês | MEDLINE | ID: mdl-36362431

RESUMO

Collagen-based polymers and their blends have attracted considerable interest for new materials development due to their unique combination of biocompatibility, physical and mechanical properties and durability. Leather, a modified natural biopolymer made from animal rawhide and the first synthetic collagen-based polymer known since the dawn of civilization, combines all these features. Rawhide is transformed into leather by tanning, a process in which the collagen is cross-linked with different agents to make it stronger and more durable and to prevent its decay. Research on the development of environmentally friendly procedures and sustainable materials with higher efficiency and lower costs is a rapidly growing field, and leather industry is not an exemption. Chrome-tanned and vegetable-tanned (chromium-free) shavings from the leather industry present a high content of organic matter, yet they are considered recalcitrant waste to be degraded by microbiological processes like anaerobic digestion (AD), a solid technology to treat organic waste in a circular economy framework. In this technology however, the solubilisation of organic solid substrates is a significant challenge to improving the efficiency of the process. In this context, we have investigated the process of microbial decomposition of leather wastes from the tannery industry to search for the conditions that produce optimal solubilisation of organic matter. Chrome-tanned and chromium-free leather shavings were pre-treated and anaerobically digested under different temperature ranges (thermophilic-55 °C-, intermediate-42 °C- and mesophilic-35 °C) to evaluate the effect on the solubilisation of the organic matter of the wastes. The results showed that the presence of chromium significantly inhibited the solubilization (up to 60%) in the mesophilic and intermediate ranges; this is the fastest and most efficient solubilization reached under thermophilic conditions using the chromium-free leather shaving as substrates. The most suitable temperature for the solubilization was the thermophilic regime (55 °C) for both chromium-free and chrome-tanned shavings. No significant differences were observed in the thermophilic anaerobic digestion of chromium-free shavings when a pre-treatment was applied, since the solubilisation was already high without pre-treatment. However, the pre-treatments significantly improved the solubilisation in the mesophilic and intermediate configurations; the former pre-treatment was better suited in terms of performance and cost-effectiveness compared to the thermophilic range. Thus, the solubilisation of chromium-free tannery solid wastes can be significantly improved by applying appropriate pre-treatments at lower temperature ranges; this is of utter importance when optimizing anaerobic processes of recalcitrant organic wastes, with the added benefit of substantial energy savings in the scaling up of the process in an optimised circular economy scenario.


Assuntos
Resíduos Industriais , Curtume , Animais , Cromo/química , Temperatura , Anaerobiose , Colágeno
4.
Molecules ; 27(20)2022 Oct 18.
Artigo em Inglês | MEDLINE | ID: mdl-36296622

RESUMO

For a long time, the production and processing of cowhide was based on the use of chrome tanning. However, the growing problem with chromium waste and its negative impact on human health and the environment prompted the search for more environmentally friendly processes such as vegetable tanning or aldehyde tanning. In the present study, we investigated the DNA-damaging effects induced in HepG2 cells after 24 h exposure to leather samples (cut into 1 × 1 cm2 rectangles) processed with different tanning agents. Our main objective was to determine which tanning procedure resulted in the highest DNA instability. The extent of treatment-induced DNA damage was determined using the alkaline comet assay. All tanning processes used in leather processing caused primary DNA damage in HepG2 cells compared to untreated cells. The effects measured in the exposed cells indicate that the leaching of potentially genotoxic chemicals from the same surface is variable and was highest after vegetable tanning, followed by synthetic tanning and chrome tanning. These results could be due to the complex composition of the vegetable and synthetic tanning agents. Despite all limitations, these preliminary results could be useful to gain a general insight into the genotoxic potential of the processes used in the processing of natural leather and to plan future experiments with more specific cell or tissue models.


Assuntos
Resíduos Industriais , Curtume , Humanos , Resíduos Industriais/análise , Projetos Piloto , Células Hep G2 , Cromo/análise , Dano ao DNA , Aldeídos
5.
Environ Sci Pollut Res Int ; 29(50): 75113-75118, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-36085223

RESUMO

The tannery industries generate a solid waste known as tannery sludge, which is composed of organic and inorganic compounds, mainly chromium (Cr). When Cr is not removed from the tannery sludge, this solid waste is metal-rich and its application could affect the soil microorganisms. Alternatively, the composting of the tannery sludge can contribute to decreasing the concentration of Cr in the composted tannery sludge (CTS). However, in some cases, the concentration of Cr remains high in the CTS. During the last 10 years, the Cr-rich CTS has been successively applied in the soil, and its effect on soil microbial properties was verified. Here, we discuss the effect of successive applications of Cr-rich CTS on soil microbes. Interestingly, the findings have shown that successive applications of Cr-rich CTS selected specific soil microbial groups with potential functions. In addition, the studies added a new focus to further research evaluating the potential effect of successive applications of Cr-rich CTS on the rare microbial community.


Assuntos
Compostagem , Poluentes do Solo , Bactérias , Biomassa , Cromo/análise , Esgotos/microbiologia , Solo , Microbiologia do Solo , Poluentes do Solo/análise , Resíduos Sólidos , Curtume
6.
Carbohydr Polym ; 295: 119838, 2022 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-35989032

RESUMO

Dialdehyde sodium alginate (DSA) is an eco-crosslinker attracting extensive interest while undergoing limited large-scale applications. Herein, we employed DSA to react with dicyandiamide (DA) for engineering a biomass-derived retanning agent (BDR) towards addressing the long-term toxicity of residual formaldehyde (FA) in leather caused by amino resins. Results confirmed that BDR reserved the structural features of DSA by grafting DA onto DSA molecules. Owing to the suitable molecular weight (main components, 1424-1462 g/mol) and abundant oxygen-containing groups of BDR endowed by DSA, BDR-treated chrome-free leather showed higher hydrothermal stability (82.4 °C), thickening ratio (13.93 %), mechanical strengths (17.2 N/mm2 for tensile strength and 120 N/mm for tear strength), and fullness compared with industrial dicyandiamide-FA-resin (DFR)-treated leather. The FA-free feature of DSA led to BDR-treated leather containing no FA, while FA in DFR-treated leather reached 591.5 mg/kg. This work provided new insights into broadening the large-scale application scopes of DSA.


Assuntos
Alginatos , Curtume , Formaldeído , Guanidinas , Resistência à Tração
7.
Regul Toxicol Pharmacol ; 133: 105222, 2022 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-35817209

RESUMO

The European Union restricted the amount of hexavalent chromium (Cr(VI)) in leather in 2015, but skin allergy cases due to Cr-tanned leather are not declining. Standardized extraction methods have been criticized to both over- and underestimate the expected amount of bioavailable Cr(VI) in leather. This study aims to evaluate the ability of four extraction solutions to reduce or preserve Cr(VI): artificial sweat solutions (ASWs) of pH 4.7, 6.5, and 8.0, and phosphate buffer (PB) of pH 8.0. This was investigated by incubating each solution with added Cr(VI) as a function of time, and then measuring the recovered Cr(VI). All solutions, especially PB, preserved Cr(VI) for 24 h. These solutions were also pre-exposed to Cr-free vegetable-tanned leather (VTL) before incubation with Cr(VI). Released vegetable tannin species strongly reduced Cr(VI), with up to 4000 µg/L added Cr(VI) reduced in all solutions after 24 h. However, after 1 h, Cr(VI) was still detectable in extraction solutions at pH 6.5 and above. The reduction of Cr(VI) in relevant extraction solutions is hence a process dependent on time, pH, and the presence of co-released leather species. All extraction solutions, but least PB, have the potential to underestimate any Cr(VI) present on the surface of leather.


Assuntos
Dermatite Alérgica de Contato , Curtume , Cromo , Humanos , Indicadores e Reagentes , Suor/química
8.
Chemosphere ; 306: 135571, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-35798151

RESUMO

Hexavalent chromium [Cr(VI)], which has a strong corrosive effect, has been reported to cause perforation of the eardrum. Trivalent chromium [Cr(III)] also has a weak corrosive effect. However, there has been no study on the effects of exposure to Cr, either Cr(VI) or Cr(III), on hearing levels in animals or humans. In this study, the effect of Cr(III) exposure on hearing levels was determined in a human study. Then the reproducibility of the results obtained in the human study and the etiology were investigated in an animal study. The mean levels of total chromium (t-Cr) in hair and toenails from 100 Bangladeshi tannery workers were >20-fold and >360-fold higher, respectively, than those in hair and toenails from 49 Bangladeshi non-tannery workers (office workers). Multivariate analysis revealed decreases of hearing levels (DHLs) at 1 k and 4 k Hz, frequencies that are crucial for understanding language, but not at 8 k and 12 k Hz, in the tannery workers. Since >99.99% of t-Cr in the wastewater that the workers were in direct contact with in the tanneries was Cr(III), the epidemiological results suggest Cr(III)-mediated DHLs in the tannery workers. The results of animal experiments in this study further showed that treatment with eardrops but not intraperitoneal injection with the same amount of Cr(III) that tannery workers might be exposed to resulted in DHL with a damaged eardrum in mice. Previous studies suggested that Cr(III) can directly reach the eardrums of tannery workers via droplets in the air. Cr(III) could also reach the eardrum via picking an ear canal with a finger contaminated with tannery wastewater including Cr(III). Taken together, the results of both human and animal studies suggest the risk of DHLs caused by damage of the eardrum through external exposure to Cr(III) via the ear canal.


Assuntos
Cáusticos , Exposição Ocupacional , Animais , Bangladesh , Cáusticos/análise , Cromo/análise , Audição , Humanos , Camundongos , Exposição Ocupacional/análise , Reprodutibilidade dos Testes , Fala , Curtume , /análise
9.
Environ Res ; 214(Pt 2): 113885, 2022 11.
Artigo em Inglês | MEDLINE | ID: mdl-35843275

RESUMO

The tannery effluent treatment plants produce tonnes of waste in the form of mixed salts containing sodium chloride, sulfate, calcium, and magnesium salts. Disposal of these mixed salts may create an environmental problem. The proposed method broadly consists of the separation of sodium chloride from reverse osmosis (RO) reject and raw-hide waste salt (preservative salt) of the tannery. This study used the physicochemical method to treat waste salt from tannery industrial waste. The addition of sodium hydroxide and sodium carbonate improved calcium and magnesium removal efficiency in the RO reject and preservative waste salts. The optimization of the sodium salt of hydroxide and carbonate is very important to remove an unwanted substance from waste salt. The sodium chloride was recovered, and the purity was about >98% which was successfully reused as preservative salt as well as in the pickling process in the tannery industry.


Assuntos
Cloreto de Sódio , Curtume , Cálcio , Resíduos Industriais/análise , Magnésio , Sais
10.
Chemosphere ; 304: 135355, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-35714952

RESUMO

A novel chrome-free tanning and formaldehyde-free post tanning process with PEG-melamine base hyperbranched polymer by complexing aluminum (Al3+) present in aluminum sulfate for eco-friendly tanning applications. The hyperbranched polymers PEGM-400-C-Al and PEGM-600-C-Al were synthesized and characterized by FT-IR, NMR, UV, and XRD. The molecular weight of polymers was assessed by GPC and subjected to the leather process. The processed crust leathers were analyzed for physical characteristics by tensile strength, tear strength, elongation, and quality assessments by hand evaluation by experts. FE-SEM analyzed collagen fibers and fiber splitting of goat skin, and COD, BOD, and total solid in spent liquor were analyzed and compared. The highlighting feature of hyperbranched polymers is (a) Improved shrinkage temperature (Ts) (85 ± 1 °C), (b) Improved physical-mechanical properties (c) Better BOD, COD, and total solids over the aluminum sulfate tanning process. This study confirmed that hyperbranched polymer is effective for tanning and post-tanning leather, which obviates the need to use toxic chromium and formaldehyde for tanning leathers.


Assuntos
Polímeros , Curtume , Cromo/química , Formaldeído , Resíduos Industriais/análise , Pele/química , Espectroscopia de Infravermelho com Transformada de Fourier
11.
Chemosphere ; 303(Pt 2): 135098, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-35643165

RESUMO

Simultaneous relocation of a group of pollutant sources in a heavily polluted area is a rare event. Such a relocation has been implemented in Hazaribagh, a tannery built-up area with heavy pollution, in Bangladesh. This provides a valuable opportunity to compare the changes in environmental conditions associated with the relocation of multiple putative sources. Our environmental monitoring for a period of 6 years at the stationary areas centered on Hazaribagh geographically revealed trivalent [Cr(III)], hexavalent [Cr(VI)] chromium, lead, iron, and manganese as tannery-related elements after the legal deadline for tannery relocation. The median Cr(III) level in canal water, into which wastewater from tanneries was directly discharged, after the relocation was 97% lower of that before the relocation, indicating a beneficial effect of the relocation. In contrast, the median Cr(VI) level in water samples just after the relocation and 2 years after the relocation were approximately 5-fold and 30-fold higher, respectively, than those before the relocation. These results indicate not only a harmful effect of the relocation but also the possibility of conversion from Cr(III) to Cr(VI) in nature. Although the health hazard indexes considering all of the tannery-related elements in all of the canal water samples before the relocation exceeded the safety thresholds, the percentages of samples in which the indexes exceeded their safety thresholds after the relocation decreased by 32.5%-45.0%. Treatment with our patented hydrotalcite-like compound consisting of magnesium and iron (MF-HT) resulted in decreases in the health hazard indexes in all of the water samples in which the indexes exceeded their safety thresholds to levels lower than their thresholds. Thus, this study shows the double-edged effects associated with the relocation and a potential solution.


Assuntos
Curtume , Poluentes Químicos da Água , Cromo/análise , Monitoramento Ambiental/métodos , Ferro , Água , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/toxicidade
12.
Sci Total Environ ; 837: 155570, 2022 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-35504371

RESUMO

Developing chrome-free and sustainable tanning agents is extremely important to the sustainability of the leather industry. Herein, we have synthesized an Al-Zr-oligosaccharides tanning agent via a simultaneous degradation and oxidation of cellulose in waste paper. The influence of the temperature and the concentrations of AlCl3 and H2O2 during the synthesis were thoroughly investigated on the properties of the tanning agent and the leather produced. The synthesis temperature and the concentration of AlCl3 were the factors primarily affecting the effective depolymerization of cellulose. They controlled the conversion of waste paper into oligosaccharides with an appropriate molecular weight to efficiently penetrate the leather matrix. In parallel, the H2O2 concentration substantially influenced the tanning performance of the Al-Zr-oligosaccharides, diminishing the chromaticity of the tanning liquid via oxidation and promoting the conversion of C2/C3/C6-OH moieties into -CHO/-COOH. These functional groups increased the surface charge of the oligosaccharides allowing more effective coordination with Al/Zr, which facilitated the penetration of Al/Zr species into the leather matrix. Once inside the leather matrix, Al and Zr were released and reacted with the collagen fibers in leather, which resulted in effective leather tanning. The process optimization revealed that up to 57% of waste paper could be converted into a low-chromaticity (4350 AU) liquid hydrolysate with the synthesis conducted at 177 °C in a system comprising 47 mM AlCl3 and 5 vol% H2O2. The application of this liquid for tanning provided leather with a shrinkage temperature (86.5 °C) sufficiently high for commercial applications. These excellent results, combined with the intrinsic green nature of our approach, exemplify a step forward to simultaneously reduce pollution and hazards in leather industries giving a second life to waste paper.


Assuntos
Resíduos Industriais , Curtume , Celulose , Peróxido de Hidrogênio , Resíduos Industriais/análise , Oligossacarídeos
13.
Indian J Public Health ; 66(1): 27-32, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35381710

RESUMO

Background: Extensive evidence of elevated chromium (Cr) in the surface and groundwater exists. However, the importance of exposure toward Cr-associated health risks in areas with tanneries is still often neglected. These situations prompted an independent research study to investigate the views of those close-knit communities who are being directly affected by this tannery village. Objectives: To establish an understanding of the local demographics and; exploratory data analysis (EDA) to discover patterns in the occurrence of diseases; measure the awareness of residents of the presence of Cr and its harmful health effects. Methods: The EDA technique was used to conduct survey studies on data to uncover patterns, identify anomalies, test hypotheses, and validate assumptions using summary statistics and graphical representations. Results: Out of 14 diseases directly linked to high Cr toxicity, the study reported high levels of diarrhea, epigastric pain, and moderate-to-severe cases of vertigo among those aged more than 22 years. With over 90 active tanneries and toxic Cr released to the environment in a town of <78 km2 area (1.2 tannery/km), there are only 15 hospitals (0.2 hospitals/km) for the population currently accommodating more than a quarter-million people daily (3205 people/km). Conclusion: New mitigation strategies must be put forth to alleviate the negative impacts of the tanneries on the residents and nature most affected as well as the population as a whole.


Assuntos
Cromo , Saúde Pública , Adulto , Cromo/análise , Cromo/toxicidade , Humanos , Índia/epidemiologia , Curtume , Adulto Jovem
14.
Mymensingh Med J ; 31(2): 421-427, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-35383761

RESUMO

Tanners are exposed to raw hides as well as to various toxic chemicals. The study was intended to find out the health problems among tannery workers. This descriptive cross-sectional study was conducted in 2019 among 223 workers working with raw hides and chemicals selected by stratified random sampling in ten tanneries of Leather Industry Area, Hemayetpur, Savar, Dhaka, Bangladesh. Data were collected by the principal investigator after taking informed written consent from the tanners using a pre-tested interview schedule and a check-list. Data were cross-checked for consistency and accuracy. All relevant ethical issues including approval from Institutional Review Board (IRB), and data quality assurance issues were taken into consideration. Analysis of data was carried out by using computer software SPSS version 20.0 with anonymity. Descriptive statistics were used to describe the data, while Chi-square test was carried out to measure statistical association. As many as 97(43.5%) workers were in age group of 15 to 24 years with a mean age of 28.4±9.5 years. An overwhelming majority 204(91.5%) were males, three-fifths 134(60.1%) of the workers were married, while 213(95.5%) tanners had religion Islam. Majority 122(54.7%) tanners had primary level of education, whereas 56(25.1%) had secondary level and 44(19.7%) had no formal schooling. The mean monthly family income was 13744.4±3485.5 Taka. More than three-fourths 170(76.2%) workers had more than four family members with over half 114(51.1%) of the workers were smokers. Of 223, over half 124(55.6%) of the workers were affected with at least one health problem. Majority of the workers suffered from skin diseases (51.6%), musculoskeletal disorders (33.1%), gastrointestinal problems (22.6%), chronic headache (14.5%) and respiratory problems (14.5%). Only 9(4.0%) workers had pre-placement orientation, while 196(66.4%) workers did not notice the necessity for pre-placement training. Of ten tanneries, cent per cent had foul smell, 80.0% each had poor lighting and discomfort temperature, 60.0% had intolerable noise, 50.0% were with poor ventilation system, and only 30.0% had adequate waste management facilities. The tanneries did not have medical facilities even for emergency conditions. Health problems are significantly associated with job duration (p<0.01), working sections (p<0.05) and smoking status (p<0.001) of the workers. The overall environment of the tanneries is far from satisfactory. Skin diseases, musculoskeletal disorders, gastrointestinal problems, chronic headache and respiratory diseases are the common identified health problems. A considerable number of workers are unconcerned for the pre-placement orientation, and do not use Personal Protective Equipments (PPEs). As a rule, Personal Protective Equipments (PPEs) are not made available to workers by the tannery authorities, and lack of treatment facilities of the tanneries is a common place.


Assuntos
Doenças Profissionais , Exposição Ocupacional , Adolescente , Adulto , Bangladesh , Estudos Transversais , Humanos , Masculino , Exposição Ocupacional/análise , Curtume , Adulto Jovem
15.
Toxicol Ind Health ; 38(2): 112-126, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-35220806

RESUMO

In the leather industry, Cr (III) is used as a basic tanning agent. The wastewater discharged from the tannery industry contains a high concentration of chromium. Recent studies indicate the genotoxic effects especially DNA damage and oxidative stress of Cr (III) in tannery workers. Cr (III) interacts with DNA to form DNA cross-links and DNA strand breaks. It also modifies the oxidative DNA base through the Haber-Weiss reaction. The present study is based on an overview of scientific literature and previous observations regarding the effects of tannery chromium effluents on exposed workers and the population in the vicinity. This study strongly suggests for use of a non-toxic substitute of chromium to be used for the tanning process and placement of tannery industries on the outskirts of the city. In South Asian developing countries like India, Pakistan and Bangladesh where the economy is strongly dependent on leather manufacturing industries, there is a need to spread proper information regarding the harmful effects of chromium toxicity to the workforce employed in the tannery and also to the people living in the surrounding area. Workers should be provided with the required safety protections like gloves, aprons, foot/shoe covers, masks, etc. Last but most important on an immediate basis is the installation of the proper efficient waste treatment plant, so that, waste should be treated before moving out of the industry.


Assuntos
Exposição Ocupacional , Saúde do Trabalhador , Cromo/análise , Dano ao DNA , Países em Desenvolvimento , Humanos , Exposição Ocupacional/efeitos adversos , Estresse Oxidativo , Curtume
16.
Environ Sci Pollut Res Int ; 29(29): 44986-44997, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-35142998

RESUMO

Some components found in the composition of the tannery sludge are nutrients for the plants; it can be considered an alternative source of fertilization as they have favorable agronomic characteristics. However, it is reported in some studies that the presence of chromium and sodium in this residue causes physiological and anatomical disturbances that inhibit the development of the plants. The objective of this study was to evaluate the influence of chromium and sodium on the physiology, anatomy, and development of Conilon coffee seedlings grown on substrates produced with tannery sludge and equivalent doses of chromium and sodium. The experiment was carried out in nursery using randomized block design, containing 5 treatments and 7 repetitions. The treatments consisted of the application of a 40% tannery sludge dose and equivalent doses of chromium and sodium mixed with a conventional substrate. Notably, the presence of sodium in the substrate caused greater damage to the plants, negatively influencing the physiology, anatomy, and, consequently, development of the plants, while the presence of chromium suggests that it does not influence much the evaluated characteristics. The treatment with tannery sludge, on the other hand, despite containing the same chromium and sodium contents, revealed a more pronounced negative influence on the physiology, anatomy, and development patterns of the seedlings. This shows that sodium and chromium alone are not the only factors responsible for the lowest growth indicators studied.


Assuntos
Cromo , Esgotos , Cromo/análise , Café , Resíduos Industriais/análise , Íons , Plântula/química , Esgotos/química , Sódio , Curtume
17.
Environ Sci Pollut Res Int ; 29(19): 28180-28193, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-34988824

RESUMO

The effluent generated by Merox unit of oil refinery was used instead of freshwater for bovine hide unhairing because of its proper composition and alkalinity. The effect of temperature, treatment period, sodium sulfide (Na2S), and calcium carbonate (CaCO3) dosage was investigated on unhairing efficiency using lutrom (unhairing slurry) prepared from the Merox effluent (effluent-based lutrom). Under similar operating conditions and chemicals' dosage, the effluent-based lutrom resulted in a higher efficiency (98.6%) than water-based lutrom (67.3%) indicating faster unhairing kinetics for the former lutrom. Moreover, an acceptable swelling (48%) and suitable mechanical properties were also observed. The experimental strategy can save 50 to 67% toxic chemicals and 100% of water consumption in unhairing, which is equivalent to US$ 34 per ton of hide, leading to zero discharge from Merox unit. Recycling of effluent-based lutrom after 3 consecutive runs was associated with a significant reduction in COD (55.6 kg/t hide) and BOD5 (11.6 kg/t hide) load. The effluent-based and conventional lutroms, before and after unhairing, were treated with ozone under moderate conditions. The FTIR results indicated a high-quality and low costly pelt benefits from the integration of wastewater treatment units of both industries in an environment-friendly manner.


Assuntos
Ozônio , Purificação da Água , Animais , Bovinos , Indústria de Petróleo e Gás , Reciclagem , Curtume , Eliminação de Resíduos Líquidos/métodos
18.
Carbohydr Res ; 511: 108501, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-35045386

RESUMO

Highly-oxidized starch (HOS) is an excellent ligand for zirconium tanning in leather making. However, oxidation reaction can only be undertaken in diluted solution due to the high viscosity of starch, which leads to high oxidant consumption and low solid content of HOS, and therefore greatly limits its industrial application. Starch was predegraded by using HCl followed by H2O2 oxidation for preparing a practical oxidized starch (OST) ligand with high solid content. HCl (5%) remarkably reduced the viscosity of starch and simplified the subsequent oxidation, resulting in a decrease in H2O2 dosage from 60% to 40% and an increase in solid content from 10% to 38%. HCl broke the α-(1-4) glycosidic bond between glucose units, and H2O2 oxidation led to the generation of abundant carboxyl groups in OST. The OST with moderate molecular weight (Mw 5609 g/mol) and carboxyl content (6.48 mmol/g) made the tanning performance of OST-Zr comparable to those of HOS-Zr and chrome tanning agents. Therefore, this work gives new insights into the crop-polysaccharides based ligands application and exhibits huge potential for promoting industrial applications of zirconium tanning.


Assuntos
Amido , Curtume , Peróxido de Hidrogênio/química , Ligantes , Oxirredução , Amido/química , Zircônio
19.
Environ Sci Pollut Res Int ; 29(23): 35382-35395, 2022 May.
Artigo em Inglês | MEDLINE | ID: mdl-35060060

RESUMO

Increased concern over the use of metal salts such as chromium, zirconium, and aluminum for tanning of hides and skins has made the leather production industry to be constantly on the lookout for organic tanning agents in place of the inorganic system. Though glutaraldehyde has been looked at as a viable option, it still lags in imparting superior strength properties to the leather and also it has been reported to have inherent toxicity. With that concept in view, this research work focuses on the usage of glyoxal along with synthetic tanning agents as a replacement for glutaraldehyde and other inorganic tanning systems. The offer level and starting pH for the glyoxal tanning process was optimized as 6% (w/w) and 5.0, respectively, and the shrinkage temperature of the collagen was found to be around 80 °C. Additionally, the controlled shrunken grain effect of the aldehyde tanning system was explored by changing the pH of the process, which helped to improve the thickness of low-grade thinner raw materials by up to 40%. The mechanism for the shrunken grain effect has also been proposed in this work by studying the dimensional changes occurring in the leather matrix upon treating skin/hide with glyoxal at different pH levels. The mechanical and strength properties of the leather were found to be better than the glutaraldehyde tanning system. The BOD/COD ratio of wastewater generated from the glyoxal process was found to be greater than 0.3 making them easily treatable. Considering all these factors, compact glyoxal-based tanning along with synthetic tanning agents can be a game-changing technology for the leather processing industry.


Assuntos
Glioxal , Curtume , Cromo/análise , Glutaral , Resíduos Industriais/análise , Indústrias
20.
Environ Sci Pollut Res Int ; 29(21): 31278-31292, 2022 May.
Artigo em Inglês | MEDLINE | ID: mdl-35006568

RESUMO

The regular practice of using sodium chloride to preserve raw animal skin triggers increasing salinity and total dissolved solids (TDS) in the surface and groundwater during rehydration soaking operations. The process disrupts the lives of animals, plants, and human beings. This paper is focused on the phyto-based short-term preservation of goatskin to reduce salinity in tannery soaking operations. The indigenous Persicaria hydropiper leaf was investigated to assess the preservation of animal skin to diminish salinity and TDS of tannery soaking wastewater. Methanol-extracted leaf was characterized by GC-MS and FTIR for chemical composition analysis and affiliated functional groups. Fresh goatskins were preserved at the preliminary, laboratory, and pilot-scale scenarios to establish the best possible mixture and monitor the moisture and nitrogen content, shrinkage temperature, microorganism analysis, and pollution load at each level. The processed leathers derived from the preserved skins with an optimal mixture of 10% leaf paste with 8% salt and conventional 50% salt were tested for their physical strength. Finally, the modification in fiber structure due to the varieties of preserving chemicals was evaluated through a scanning electron microscope (SEM) and detected insignificant variation of leather fibers. The findings reported in this study can be applied to the industrial level and remove certain amounts of salinity and TDS from tannery soaking wastewater.


Assuntos
Curtume , Animais , Salinidade , Pele/química , Cloreto de Sódio/análise , /análise
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