Vegetable Tannins as Chrome-Free Leather Tanning

Teklemedhin, Taame Berhanu; Gebretsadik, Tesfamariam Tekle; Gebrehiwet, Tesfu Berhane; Gebrekidan, Gebrehiwot Asfaha; Edris, Mahamedbirhan; Teklegiorgis, Negasi Teklay; Hagos, Kokeb Brhane

doi:https://doi.org/10.1155/2023/6220778

Advances in Materials Science and Engineering

On this page

Abstract Introduction Materials and Methods Results and Discussion Conclusions Data Availability Conflicts of Interest Acknowledgments References Copyright Related Articles

Research Article | Open Access

Volume 2023 | Article ID 6220778 | https://doi.org/10.1155/2023/6220778

Vegetable Tannins as Chrome-Free Leather Tanning

Taame Berhanu Teklemedhin,¹Tesfamariam Tekle Gebretsadik,²Tesfu Berhane Gebrehiwet,¹Gebrehiwot Asfaha Gebrekidan,³Mahamedbirhan Edris,⁴Negasi Teklay Teklegiorgis,¹and Kokeb Brhane Hagos¹

Academic Editor: Anil Singh Yadav

Received19 Jan 2023

Revised27 Aug 2023

Accepted20 Sept 2023

Published28 Sept 2023

Abstract

The purpose of this study is to replace chrome tannins with ecofriendly vegetable tannins as an alternative solution to prevent the public health and the environmental pollution. Vegetable tannin was extracted from Cassia singueana bark using an aqueous extraction method and applied on sheep pickle pelt. Optimum tannin extraction parameters were identified at powder concentration of 80 g/L, extraction temperature of 100°C, and extraction time of 120 mins. Chemical functionality of Cassia singueana extracted tannins was evaluated via FT-IR spectroscopy. Hence, the FT-IR spectrum confirmed the presence of wide band of phenolic hydroxyl (OH⁻) and carboxyl (C-O) groups connected with the aromatic ring. Moreover, physicochemical performance of the Cassia singueana extract tanned leather sample was scientifically examined and showed comparable results to conventional Mimosa tanned leather sample. The shrinkage temperature of Cassia singueana extract tanned leather recorded 83°C which is slightly higher than that of Mimosa extract (standard), 80°C. The results of mechanical properties such as tensile strength, tear strength, and elongation at break of Cassia singueana extract tanned leather sample are 15.6 N/mm², 24.2 N/mm, and 45.3%, respectively, which are relatively higher than those of Mimosa extract tanned leather sample. A relatively higher reduction level of pollution load (BOD, COD, and TDS) was observed in the wastewater released from Cassia singueana bark extract compared to the Mimosa extract (standard). Finally, findings from this study revealed that Cassia singueana bark extract could be considered as an alternative source of vegetable tannins to reduce the consumption of chrome tanning in the leather tanning industry.

1. Introduction

Leather production is the earliest technology that has been termed man’s first manufacturing process [1, 2]. It involves the conversion of raw animal hides and skin into a valuable leather material. It shows enhanced property of thermal stability, abrasion, and water penetration due to the reaction between reactive functionalities of tannins and collagen protein of skins and hides [3]. Tanning is a process of treating skins and hides with organic or inorganic chemicals to produce a leather product with improved softness, antimicrobial properties, strength, heat resistance, and stable structure [4]. This process is considered as a major process in leather production which comprises of further chemical reactions and mechanical actions.

Before the 19^th century, traditional tanneries used organic compounds obtained from roots, leaves, barks, and wood of different plants as tannins to convert skin to leather [2, 5]. This vegetable tanning process has been developed in the Mediterranean region [6] and practiced for centuries mainly in Europe until the end of the 19^th century [2, 7]. After the 19^th century, vegetable tanning has been gradually replaced by chemical tanning. Chrome tanning is the most extensively used in the global leather manufacturing industry [8] which contributes about 90% of the total tanning consumption worldwide. It provides excellent features such as thermal stability and physical properties to leather product [9–14].

However, chrome (Cr_VI and Cr_III) compounds in leather tanning produce huge amount of chrome-containing waste, which is openly disposed to the environment and leads to various health and environmental concerns and disorders [15–18]. Chromium-rich solid and liquid wastes can affect the human and animal respiratory organs, skin, liver, and kidneys. It can also cause cancer and infertility [19].

Considering the negative impact of chrome tanning, many researchers are exploring sustainable and green manufacturing processes by using alternative environmentally friendly chrome tanning processes or replacing chrome chemicals with vegetable tannins extracted from different parts of plants for leather industry [10, 20–23]. Application of vegetable tannin is considered to be cheap, ecofriendly, and sustainable and regarded as an alternative to chrome tanning [2, 24–26].

Varieties of vegetable tannins have been used around the world. Few vegetable tannins applied in different parts of the globe with variable concentrations are as follows: ashan bark 12%, chestnut 10.7%, gurjan bark 35%, quebracho 20%, Goran bark 26–36%, sumack leaves 25%, cutch 35%, avaram bark 18%, konam bark 11–14%, bambul bark 12%, myrobalam 30–40%, sandri bark 11%, dhundri bark 28–31%, kahra 16%, divi 35–45%, gorra bark, and behra nuts [27, 28]. The pods of Acacia arabica (Bagaruwa H) and wattle bark are also another source of vegetable tannins which are commonly used in Nigeria [29].

Such vegetable tannins are present in several plant species such as the bark of Acacia mearnsii and Cassia singueana, wood of Schinopsis balansae, bark of Quercus spp, and leaves of green tea and hamamelis plant species [30, 31]. Vegetable tannins can react with functional groups of collagen in hides and skins and form different bonds such as ionic, covalent, hydrogen bond, and weak hydrophobic interaction [25].

Cassia singueana plants (Figure 1) are short shrubs that grow to a height of 1.2 to 1.5 m with small yellow flowers which are widely found in different parts of Africa [32]. They are widely used as traditional medicinal applications to fight malaria and fever which are administered in different mechanisms [33, 34]. Cassia singueana leaf, stem, bark, and root extract possess antiulcer effect, stomach complaint and troubles, antioxidant effect, and fever reduction [35–38]. Toxicity study of Cassia singueana leaf extract on animals proved that the leaf extract is nontoxic [39, 40]. Furthermore, Cassia singueana bark extracted pigment was successfully used as dyeing crust for leather [29] and silk fabric [41] in the presence of natural mordant.

Therefore, the aim of this research is to extract vegetable tannin from Cassia singueana bark in comparison with the standards and apply on sheepskin as ecofriendly vegetable tannin to minimize the health and environmental impact of chrome tanning.

2. Materials and Methods

2.1. Materials

Fresh bark of the Cassia singueana was collected from Tigray, Northern Ethiopia. One full-size wet salted sheepskin, chemical reagents, devices, and equipment are used from the Ethiopian Leather Industry Development Institute (LIDI), Addis Ababa, Ethiopia. The mimosa extracted tannin powder was obtained from Mimosa Extract Company.

2.2. Methods

2.2.1. Extraction of Tannins from Bark of Cassia singueana Plant

Matured barks of the Cassia singueana were randomly collected from the South and Southeastern zone of Tigray, Northern Ethiopia, from February to April 2021. The Cassia singueana barks were washed using distilled water and stockpiled in the refrigerator for a day. Then, the size of the barks was reduced using mechanical shredder and air dried at room temperature for seven days. The dried bark samples were ground using a grinder and sieved with 0.5 µm mesh size to obtain fine powder.

The extraction process of vegetable tannins from the bark of the Cassia singueana is illustrated in Figure 2. Vegetable tannin of the bark of Cassia singueana was extracted using an aqueous extraction method via an ecoinfrared dyeing machine. The powder was immersed in distilled water using varied combinations of powder concentration (40, 60, and 80 g/L), temperature (60, 80, and 100°C), and time (60, 90, and 120 min). The number of experimental trials (10 trials) and combinations of the parameters were conducted using statistical Minitab software. The resultant tannin solution obtained from each trial was subjected to cool and filtered solution using double-layered sateen polyester followed by Whatman No. 1 filter paper. The filtrate solution was exposed to a vacuum dryer at 60°C until the solvent was completely evaporated. The percent yield of extract for each trial was calculated using the following equation:

Finally, a trial combination attaining the maximum % yield was taken as the optimum condition of tannin extraction from the bark of the Cassia singueana plant.

2.2.2. Characterization of Vegetable Tannins

Fourier transform infrared (FT-IR) spectroscopy (Perkin Elmer FT-112 Spectrum) was used to characterize the available functional groups in the tannin material. The FT-IR test was recorded in transmittance mode in the range of 4,000 cm⁻¹ to 400 cm⁻¹ wavelength.

2.2.3. Application of Tannins on Sheepskin

Fresh sheepskin was obtained from the Ethiopian Leather Industry Development Institute for the trial of Cassia singueana bark extract tannins. After identification of the optimum parameters for tannin extraction and the FT-IR analysis of the extracted tannins, the beam house operation was performed and the sheepskin pickle pelts were dissected into two equal portions. One portion was used for tanning with Cassia singueana extract and the other part was used for tanning with Mimosa vegetable tannin (standard) for comparison purpose at laboratory scale testing drum under the same conditions using conventional recipes as shown in Table 1.

2.2.4. Performance Evaluation of Tanned Leather

(1) Mechanical Strength of Tanned Leather Samples. Cassia singueana and Mimosa extract tanned leather samples were examined by mechanical features such as elongation at break, tear, and tensile strength. The test samples were prepared as per the International Union of Leather Technologists and Chemists Societies (IULTCS) method. The samples were conditioned under the standard temperature 20 ± 2°C and relative humidity 65 ± 2% for two days [42]. Elongation at break and tensile strength of tanned leather samples were measured according to IULTCS/IUP 6 in agreement with ISO 3376 : 2011. Similarly, tear strength was measured based on IULTCS/IUP 8 in agreement with the ISO 3377-2 : 2016 test method.

(2) Shrinkage Temperature of the Tanned Leather. The shrinkage temperature (Ts) of the tanned leather samples was measured according to the IULTCS/IUP 16 in agreement with ISO 3380 : 2015 test method to evaluate the thermal efficiency and hydrothermal stability of leather materials.

2.2.5. Chemical Constituents in Vegetable Tanned Leather

The chemical constituents like % of insoluble ash, total ash content, % hide substance, % moisture, degree of tannage, % oils and fats, and % water-soluble maters for both experimental and control leather samples were evaluated as per the standard procedures [43].

2.2.6. Spent Liquors after Vegetable Tanning

The amount of chemical oxygen demand (COD), biological oxygen demand (BOD), and total dissolved solids (TDS) of consumed liquor after leather tanning using Cassia singueana extract and Mimosa (standard tannin) were analyzed as per the standard procedures [44, 45].

3. Results and Discussion

3.1. Extraction of Tannins from Cassia singueana Bark

An aqueous method was used for the extraction of vegetable tannins from Cassia singueana bark. Different scholars reported that an aqueous extraction method is relatively economically feasible method [29, 46]. Distilled water was used as a solvent for the extraction of tannins at different combinations of bark powder concentration, extraction temperature, and time. The schematic diagram of the actual tannin extraction process is presented in Figure 3.

3.2. Optimization of Tannin Extraction

3.2.1. Percentage Yield of Extracted Tannin Solution

The percent yields of extracted tannins from different combinations of experimental trials are calculated using equation (1) which supports to optimize the extraction parameters. The higher % yield revealed that the trial combination contained the optimum tannin extraction conditions. The % yields of tannins from different combinations of experimental trials are presented in Table 2. A minimum of 9% tannin yield was recorded from trial two at a combination of concentration of 40 g/L, temperature of 60°C, and time of 60 min and a maximum of 36.83% tannin yield from trial five at a combination of concentration of 80 g/L, temperature of 100°C, and time of 120 min. Hence, concentration (80 g/L), extraction temperature (100°C), and extraction time (120 min) were selected as the optimum extraction conditions of tannins from Cassia singueana bark.

3.3. Effect of Extraction Parameters on % Yield of Tannins

3.3.1. Effect of Bark Powder Concentration on % Yield of Tannins

The effect of powder concentration on tannin % yield was examined by using different bark powder concentrations (20, 40, 60, 80, 100, and 120 g) at constant extraction time, temperature, and amount of solvent. It is clearly visualized in Figure 4 that the % yield increased sharply as the powder concentration was raised from 20 to 80 g. This is in agreement with mass transfer theory because the former presents a higher contact area between the solute and the solvent. Conversely, the % yield started to decrease abruptly while the powder concentration was still under incremental mode. Further increase in powder concentration restricted the free movement of particles, leading to reduction solubility and % yield of tannin extract.

3.3.2. Effect of Temperature and Time on % Yield of Tannins

To investigate the effect of temperature on % yield of tannins, different temperature ranges (40, 60, 80, 100, and 120°C) were examined at constant extraction time and powder concentration. The % yield of tannins showed a continuous increment from 8.1% to 32.12% with a subsequent increase in temperature from 40°C to 120°C (Figure 5(a)). The higher the temperature and agitation values, the higher kinetic movement of the particles achieved. This also supported to enhance the rate of mass transfer of materials from the surface of the solute to the bulk of the solution which could foster the rate of diffusion and solubility of the extracted substances. This in turn enhanced the % yield of the extracted tannins (∼32.12%) [47].

(a)

(b)

To examine the effect of extraction time on % yield of tannins, different time intervals (30, 60, 90, 120, and 150 min) were considered. The duration of tannin extraction was arranged in an increasing trend while the other parameters such as temperature, sample size, agitation, and amount of solvent were kept constant. High % yield of tannin extract was achieved with an increased duration of extraction time. The contact time of the powder with a solvent increased from 30 min to 150 min and the % yield also increased from 6% to 21.5% (Figure 5(b)) which could be due to enhanced solubility/dissolution of the powder in the solvent.

3.4. Characterization of the Extracted Tannins

Cassia singueana extracted tannins were characterized by using physicochemical parameters and FT-IR spectroscopy.

3.4.1. Physicochemical Analysis

The physicochemical analysis (color and pH) of Cassia singueana bark extracted tannins and Mimosa standard is shown in Table 3. The pH level of the Cassia singueana bark extract is 5.16 and that of Mimosa is 5.3. The variation in pH is probably due to the method of extraction, type of solvent, and plant species. The color of the tannin is exactly the same, pink. The required pH range for effective leather tanning is in between 4 and 6 [48] which is in agreement with the findings of the present study.

3.4.2. Characterization Using FT-IR Spectroscopy

The FT-IR spectrum of Cassia singueana barks extracted tannin is shown in Figure 6. The most important peaks considered for the standard tannin in FT-IR analysis are 3423.03 cm⁻¹, 1520.87 cm⁻¹, 1062.12 cm⁻¹, 1620.02 cm⁻¹, and 1350 cm⁻¹ [49]. A broad band at 3286.84 cm⁻¹ shows the existence of the phenolic hydroxyl (-OH) groups attached to benzene ring. Another peak at 2922.28 cm⁻¹ represents C-H and CH₂ stretching vibrations of aliphatic hydrocarbons. Particularly, specific peaks at 1153.48 cm⁻¹, 1101.4 cm⁻¹, and 1014.6 cm⁻¹ showed the presence of carboxylic (C-O) groups attached to aromatic ring structures. Typically, the bands at 1650–1400 cm⁻¹, 1400–1100 cm⁻¹, and 1100–600 cm⁻¹ belong to C=C, C-O, and C-H stretching vibrations of phenolic aromatic groups, respectively [50].

The FT-IR test results reveal that the vegetable tannins extracted from the bark of Cassia singueana plant are condensed tannins. In case of the condensed tannins, the monomers are interlinked through C-C or C-O-C bonds. Mostly, condensed tannins are known by their medical properties attributed to tannins [51]. The condensed tannins are also the major constituents in human nutrition, such as red wine, cocoa, chocolate, grape seeds, and others. These tannins are more richly found in different plant species with complex structure as compared to hydrolysable tannins [51].

3.5. Application of Tannins on Sheepskin

Pretanning of leather production was carried out based on the following conventional process: full-size sheepskin was treated with 50% of water and 7% of salt at 25°C for 15 min and then treated with 0.2% H₂SO₄ for 1 h in a drum rotating at 12 rpm. The skin was washed using tap water, and the pH was adjusted to 4.0 before treatment with vegetable tannin extract. Finally, the pickle pelt was bisected into two equal portions to test Cassia singueana extract and Mimosa (standard) extract experiment. Then, two batches of tannage process were arranged; tanning of the pickle pelt was performed using Cassia singueana bark extract and Mimosa tannin extract (standard) as control.

The weight of tannin extract was 25% of the pickle pelt’s weight. The treatment was subjected to drumming for two hours at a temperature of 37°C and pH 3.9. Finally, the bath was neutralized to pH 4.2 to enhance resistance of the tanned skins to boiling water followed by washing and fatliqouring. Then, the leather was piled and dried. The dried leather was subjected to physical and chemical tests. The qualities of tanned leather samples are shown in Figure 7 which are evaluated according to the international standard methods.

3.6. Performance Testing

3.6.1. Mechanical Strength of Tanned Leather Sample

The results of % of elongation at break, tear strength, and tensile strength of tanned leather samples are shown in Table 4. The Cassia singueana extract tanned leather samples offered tensile strength of 15.6 N/mm², which is relatively better than the Mimosa (standard) tannin treated leather, 14.8 N/mm². This proved that the Cassia singueana extract possessed better tanning performance compared to that of the Mimosa tannin standard. Besides, quality of the hide collagen fibers influences tensile strength of the tanned leather.

The percent elongation of Cassia singueana extract and Mimosa (standard) tannin tanned leather samples recorded 45.3% and 38.7%, respectively. Cassia singueana extract tanned leather shows better percent elongation as compared to leather tanned with Mimosa standard tannin. According to IULTCS/IUP 6, quality leather should possess percent elongation greater than 40. Though the Mimosa tanned leather deviated a little, the percent elongation of Cassia singueana extract treated leather sample fulfilled the minimum values set by the IULTCS/IUP 6 standard.

Tear strength is the force used to initiate or continue a tear in leather under specified conditions. The tear strength of Cassia singueana extract and Mimosa standard tannin tanned leather samples recorded 24.2 N/mm and 22.5 N/mm, respectively. Both values are higher than the minimum allowed standard, that is, 20 N/mm set by the IULTCS/IUP 8. However, the result of tear strength for Cassia singueana extract tanned leather sample is slightly higher than that of the Mimosa standard extract tanned leather sample. Probably, Cassia singueana extract is rich enough with phenolic hydroxyl (⁻OH) functional groups. Phenolic hydroxyl (⁻OH) groups further create bond interaction and crosslinking with cationic amine (NH₃⁺) groups of the leather collagen protein to form hydrogen bond and polyfunctional crosslinkings [42]. The mechanism tannin contains phenolic hydroxyl groups which can interact/crosslink with cationic amino groups of collagen protein by polyfunctional crosslinking to form hydrogen bonds [52, 53] to form nonputrescible and hydrothermally stable product called leather [54] (Figure 8). Moreover, there are physical hydrophobic interactions between the hexagonal structure of tannin and the protein structure which made the leather sable and resist external forces [55].

3.6.2. Hydrothermal Stability of Tanned Leather

Shrinkage temperature (Ts) is among the most important leather testing parameters which illustrate thermal stability of tanned leather collagen. Shrinkage temperature is the temperature at which leather starts shrinking in hot water [56]. Thermally stable leather withstands shrinkage even at high temperature. This is due to the formation of cross-links and a variety of strong bonds between the tannin components and the leather collagen. According to IULTCS/IUP 16, stating the shrinkage temperature of tanned leather should not be below 75°C [57, 58] confirmed that the leather samples tanned under this study are hydrothermally stable.

The shrinkage temperatures recorded for Cassia singueana extract and Mimosa (standard) tannins tanned leather samples are 83°C and 80°C, respectively. The reason for the higher shrinkage temperature of Cassia singueana extract tanned leather over the Mimosa extract tanned leather is probably due to the formation of excess cross-links/bonds between amine (NH₃⁺) ions of the leather collagen and the hydroxyl (OH⁻) ions of tannins (as shown in Figure 8) [57, 59].

3.7. Chemical Constituents Analysis of Tanned Leather Sample

The analysis of chemical constituents such as ash content, moisture content, fat content, hide substances, water-soluble matter, and degree of tanning was studied for tanned leather samples, and their results are shown in Table 5. The moisture contents of Cassia singueana extract and Mimosa (standard) tannins tanned leather samples were recorded 8.974 and 9.017, respectively. Similarly, ash contents are 3.255 and 3.751, for Cassia singueana extract and Mimosa (standard) tannins tanned leather samples, respectively. Both the results of moisture and ash contents are within the acceptable range of leather production standards [60, 61]. All the chemical constituents of Cassia singueana extract tanned leather samples showed lower values compared to the Mimosa extract treated leather sample. Furthermore, the degree of tanning for both leather samples is in agreement with a minimum standard value of 50% [62].

3.7.1. Pollution Load for Spent Liquors after Tanning

The environmental impact (BOD, COD, and TDS) of the spent liquors after leather tanning with Cassia singueana extract and Mimosa extract (standard) was evaluated, and the results are illustrated in Table 6. A significant reduction of BOD, COD, and TDS results was observed for Cassia singueana extract tanned leather samples as compared to the Mimosa extract tanned leather samples. This might be due to the impacts of the soil type grown, type of fertilizers used during cultivation, and climate conditions. Vegetable tanning has significant importance in the reduction of pollution loads as compared to chemical tanning processes such as chrome tanning [63]. Therefore, the tannin material extracted from Cassia singueana bark could be suggested to be used as commercial tanning material in the leather manufacturing industries.

4. Conclusions

Vegetable tannin extracted from the bark of the Cassia singueana plant could be used as an alternative source of leather tanning replacing chrome tanning, an environmental friendly vegetable tannins replacing the use of chromium salts in the leather tanning industry. The plant is widely available in Ethiopia mainly in the northern part of the country, which makes the raw material cheap. Using this plant extract for the tanning of leather would give the benefits of reducing the import of synthetic tannins and minimizing environmental pollution. The efficiency of tanned leather with Cassia singueana bark extract was equivalent to those tanned with conventional Mimosa in all aspects of leather quality parameters and attained the results of all parameters more than the minimum set of standards. The result of pollution loads such as COD, BOD, and TDS reduction level of tanning liquors in experimental Cassia singueana bark extract tanning observed waste reduced as compared to the control Mimosa tanning. Additional advantages of the Cassia singueana plant over the Mimosa are its antimicrobial properties and medicinal applications, its ease of cultivation and growing, and its wide availability in Ethiopia and most of the African continent. In general, considering the environmental pollution aspect, the vegetable tannins extracted from the bark of the Cassia singueana plant can be used commercially as an alternative ecofriendly leather tanning. Moreover, another scientific research can be investigated on the possibility of using the residual extract/by-product of tannin extract as organic fertilizer.

Data Availability

All the data used in this study are provided in the manuscript.

Conflicts of Interest

The authors declare that they have no conflicts of interest.

Acknowledgments

The authors acknowledge the Ethiopian Institute of Technology-Mekelle (EiT-M), Mekelle University for funding a research project registered as RDPDO/MU/EiTM/General Junior/007/20. Besides, the authors are grateful to acknowledge Leather Industry Development Institute (LIDI), Addis Ababa, for providing a laboratory facility during this study.

References

S. Adeel, M. Habiba, S. Kiran, S. Iqbal, S. Abrar, and C. M. Hassan, “Utilization of colored extracts for the formulation of ecological friendly plant-based green products,” Sustainability, vol. 14, no. 18, Article ID 11758, 2022.
View at: Publisher Site | Google Scholar
B. D. Barker, V. Daniels, R. Eaton et al., Conservation Science (No. PUBDB-2017-150542), Royal Society of Chemistry, London, UK, 2006.
A. D. Covington, Tanning Chemistry: The Science of Leather, Royal Society of Chemistry, London, UK, 2009.
D. Gao, P. Wang, J. Shi et al., “A green chemistry approach to leather tanning process: cage-like octa (aminosilsesquioxane) combined with Tetrakis (hydroxymethyl) phosphonium sulfate,” Journal of Cleaner Production, vol. 229, pp. 1102–1111, 2019.
View at: Publisher Site | Google Scholar
R. Reed, Ancient Skins, Parchments and Leathers, Seminar Press, Cambridge, MA, USA, 1972.
E. Haslam, “Vegetable tannage: where do all the tannins go?” Journal of the Society of Leather Technologists and Chemists, vol. 81, no. 2, pp. 45–51, 1997.
View at: Google Scholar
L. A. Clarkson, “Developments in tanning methods during the post-medieval period (1500–1850),” Leather Manufacture through the Ages, Proceedings of the 27th East Midlands Industrial Archaeology Conference, vol. 27, pp. 11–23, 1983.
View at: Google Scholar
Y. Yu, Y. Lin, Y. Zeng et al., “Life cycle assessment for chrome tanning, chrome-free metal tanning, and metal-free tanning systems,” ACS Sustainable Chemistry & Engineering, vol. 9, no. 19, pp. 6720–6731, 2021.
View at: Publisher Site | Google Scholar
M. Prokein, M. Renner, E. Weidner, and T. Heinen, “Low-chromium-and low-sulphate emission leather tanning intensified by compressed carbon dioxide,” Clean Technologies and Environmental Policy, vol. 19, no. 10, pp. 2455–2465, 2017.
View at: Publisher Site | Google Scholar
C. R. China, A. Hilonga, S. S. Nyandoro et al., “Suitability of selected vegetable tannins traditionally used in leather making in Tanzania,” Journal of Cleaner Production, vol. 251, Article ID 119687, 2020.
View at: Publisher Site | Google Scholar
A. D. Covington, “What is the future of (chrome) tanning leather manufacture in the new millenium,” Regional Programme for Pollution Control in the Tanning Industry in South East Asia, UNIDO, Vienna, Austria, 2000.
View at: Google Scholar
C. R. China, M. M. Maguta, S. S. Nyandoro, A. Hilonga, S. V. Kanth, and K. N. Njau, “Alternative tanning technologies and their suitability in curbing environmental pollution from the leather industry: a comprehensive review,” Chemosphere, vol. 254, Article ID 126804, 2020.
View at: Publisher Site | Google Scholar
B. Ocak, “Film-forming ability of collagen hydrolysate extracted from leather solid wastes with chitosan,” Environmental Science and Pollution Research, vol. 25, no. 5, pp. 4643–4655, 2018.
View at: Publisher Site | Google Scholar
E. Tao, D. Ma, S. Yang, Y. Sun, J. Xu, and E. J. Kim, “Zirconium dioxide loaded montmorillonite composites as high-efficient adsorbents for the removal of Cr3+ ions from tanning wastewater,” Journal of Solid State Chemistry, vol. 277, pp. 502–509, 2019.
View at: Publisher Site | Google Scholar
Z. Sebestyén, E. Jakab, E. Badea, E. Barta-Rajnai, C. Şendrea, and Z. S. Czégény, “Thermal degradation study of vegetable tannins and vegetable tanned leathers,” Journal of Analytical and Applied Pyrolysis, vol. 138, pp. 178–187, 2019.
View at: Publisher Site | Google Scholar
C. Rolence, “An eco-friendly tanning method using plant barks and their combination with aluminium sulphate from kaolin for leather industry,” NM-AIST, Arusha, Tanzania, 2021, Doctoral Dissertation.
View at: Google Scholar
É. Hansen, P. M. de Aquim, and M. Gutterres, “Environmental assessment of water, chemicals and effluents in leather post-tanning process: a review,” Environmental Impact Assessment Review, vol. 89, Article ID 106597, 2021.
View at: Publisher Site | Google Scholar
Y. S. Hedberg, “Chromium and leather: a review on the chemistry of relevance for allergic contact dermatitis to chromium,” Journal of Leather Science and Engineering, vol. 2, pp. 20–15, 2020.
View at: Publisher Site | Google Scholar
Al-Mizan, M. A. I. Juel, M. S. Alam, J. Pichtel, and T. Ahmed, “Environmental and health risks of metal-contaminated soil in the former tannery area of Hazaribagh, Dhaka,” SN Applied Sciences, vol. 2, no. 11, pp. 1915–1917, 2020.
View at: Publisher Site | Google Scholar
R. K. Das, A. Mizan, and F. T. Zohra, “Application of indigenous plant-based vegetable tanning agent extracted from xylocarpus granatum in semi-chrome and chrome retanned leather production,” Tekstil ve Konfeksiyon, vol. 32, no. 3, pp. 258–264, 2022.
View at: Publisher Site | Google Scholar
C. M. Mireia, C. C. Felip, B. A. Grau, O. Lluís, and B. D. Anna, “Exploring the feasibility of substituting Mimosa tannin for pine bark powder. A LCA perspective,” Cleaner Engineering and Technology, vol. 7, Article ID 100425, pp. 1–9, 2022.
View at: Publisher Site | Google Scholar
J. Shi, R. Zhang, Z. Mi, S. Lyu, and J. Ma, “Engineering a sustainable chrome-free leather processing based on novel lightfast wet-white tanning system towards eco-leather manufacture,” Journal of Cleaner Production, vol. 282, Article ID 124504, 2021.
View at: Publisher Site | Google Scholar
A. D. Covington and W. R. Wise, “Current trends in leather science,” Journal of Leather Science and Engineering, vol. 2, pp. 28-29, 2020.
View at: Publisher Site | Google Scholar
P. Auad, F. Spier, and M. Gutterres, “Vegetable tannin composition and its association with the leather tanning effect,” Chemical Engineering Communications, vol. 207, no. 5, pp. 722–732, 2020.
View at: Publisher Site | Google Scholar
M. Fraga-Corral, P. García-Oliveira, A. G. Pereira et al., “Technological application of tannin-based extracts,” Molecules, vol. 25, no. 3, p. 614, 2020.
View at: Publisher Site | Google Scholar
S. R. Khan and R. U. Khan, “Eco-friendly valorization and utilization of plant waste as a source of tannin for leather tanning,” Sustainability, vol. 15, no. 5, p. 3884, 2023.
View at: Publisher Site | Google Scholar
K. T. Sarkar, Theory and Practice of Leather Manufacturer, 4th edition, 1995.
R. Wemegah, “Vegetable tanning in Bolgatanga: challenges and the way forward,” Arts and Design Studies, vol. 16, pp. 27–37, 2014.
View at: Google Scholar
T. Berhanu and S. Ratnapandian, “Extraction and optimization of natural dye from Hambo Hambo (Cassia singueana) plant used for coloration of tanned leather materials,” Advances in Materials Science and Engineering, vol. 2017, Article ID 7516409, 5 pages, 2017.
View at: Publisher Site | Google Scholar
A. A Bele, V. M Jadhav, and V. J. Kadam, “Potential of tannnins: a review,” Asian Journal of Plant Sciences, vol. 9, no. 4, pp. 209–214, 2010.
View at: Publisher Site | Google Scholar
B. Lochab, S. Shukla, and I. K. Varma, “Naturally occurring phenolic sources: monomers and polymers,” RSC Advances, vol. 4, no. 42, pp. 21712–21752, 2014.
View at: Publisher Site | Google Scholar
V. Kawanga and C. H. Bosch, Senna Singueana (Delile) Lock, PROTA, 2007, http://database.prota.org/search.htm [accessed 16.02.14].
M. G. Hiben, “Evaluation of Senna singueana leaf extract as an alternative or adjuvant therapy for malaria,” Journal of Traditional and Complementary Medicine, vol. 6, no. 1, pp. 112–117, 2016.
View at: Publisher Site | Google Scholar
A. Ripanda, A. Luanda, G. S. Mtabazi, and J. J. Makangara, Senna Singueana (Delile) Lock: Ethnomedicinal Uses and Medicinal Properties, Heliyon, Reinhold Publishing Corp, New York, NY, USA, 2023.
View at: Publisher Site
O. J. Ode and O. V. Asuzu, “Investigation of cassia singueana leaf extract for antiulcer effects using ethanol-induced gastric ulcer model in rats,” International Journal of Plant, Animal and Environmental Sciences, vol. 1, no. 1, pp. 1–7, 2011.
View at: Google Scholar
M. Gebrelibanos, “<em>In vitro</em> Erythrocyte Haemolysis Inhibition Properties of <em>Senna singueana</em> Extracts,” Momona Ethiopian Journal of Science, vol. 4, no. 2, pp. 16–28, 2012.
View at: Publisher Site | Google Scholar
R. C. Moellering, J. R. Graybill, J. E. McGowan, and L. Corey, “Antimicrobial resistance prevention initiative—an update: proceedings of an expert panel on resistance,” American Journal of Infection Control, vol. 35, no. 9, pp. S1–S23, 2007.
View at: Publisher Site | Google Scholar
O. J. Ottu, S. E. Atawodi, and E. Onyike, “Antioxidant, hepatoprotective and hypolipidemic effects of methanolic root extract of Cassia singueana in rats following acute and chronic carbon tetrachloride intoxication,” Asian Pacific Journal of Tropical Medicine, vol. 6, no. 8, pp. 609–615, 2013.
View at: Publisher Site | Google Scholar
Y. Ibrahim Alkali, A. O. Jimoh, and U. Muham, “Acute and sub-chronic toxicity studies of methanol leaf extract of Cassia singueana F. (Fresen) in Wistar Rats,” Herb Med, vol. 4, no. 2, p. 6, 2018.
View at: Google Scholar
E. Tasiam, R. Primaharinastiti, and W. Ekasari, “In vitro antimalarial activity and toxicity studies of Johar (Cassia siamea) leaves from three different locations,” African Journal of Infectious Diseases, vol. 14, no. 2, pp. 23–29, 2020.
View at: Publisher Site | Google Scholar
T. B. Teklemedhin and L. H. Gopalakrishnan, “Environmental friendly dyeing of silk fabric with natural dye extracted from Cassia singueana,” Plant. J Textile Sci Eng S, vol. 3, p. 2, 2018.
View at: Google Scholar
M. H. Tekalign, T. S. Badessa, and S. A. Mohammed, Sodom Apple (Solanum Incanum) Plant Material: A Greener Approach for Goat Skin Tanning Process, 2020.
F. O'flaherty, W. T. Roddy, and R. M. Lollar, “The chemistry and technology of leather,” Evaluation of leather. The chemistry and technology of leather, vol. 4, Evaluation of leather, 1965.
View at: Google Scholar
Apha, Standard Methods for the Examination of Water and Wastewater, Apha, American Public Health Association, Washington, D.C., USA, 1985.
L. S. Clesceri, A. E. Greenberg, and R. R. Trussell, “American Public Health.” American Water Works, Water Pollution Control, Standard Methods for the Examination of Water and Wastewater, American Public Health Association, Washington, DC, USA, 17th edition, 1989.
J. Li and F. Maplesden, “Commercial production of tannins from radiata pine bark for wood adhesives,” Transactions of the Institution of Professional Engineers New Zealand: Electrical, Mechanical, Chemical, Engineering Section, vol. 25, no. 1, pp. 46–51, 1998.
View at: Google Scholar
S. Jokić, D. Velić, M. Bilić, A. Bucić-Kojić, M. Planinić, and S. Tomas, “Modelling of solid-liquid extraction process of total polyphenols from soybeans,” Czech Journal of Food Sciences, vol. 28, no. 3, pp. 206–212, 2010.
View at: Publisher Site | Google Scholar
A. Kuria, J. Ombui, A. Onyuka et al., Quality Evaluation of Leathers Produced by Selected Vegetable Tanning Materials from Laikipia County, Kenya, 2016, http://repository.dkut.ac.ke:8080/xmlui/handle/123456789/7854.
G. Tondi and A. Petutschnigg, “Middle infrared (ATR FT-MIR) characterization of industrial tannin extracts,” Industrial Crops and Products, vol. 65, pp. 422–428, 2015.
View at: Publisher Site | Google Scholar
G. Tondi, “Tannin-based copolymer resins: synthesis and characterization by solid state 13C NMR and FT-IR spectroscopy,” Polymers, vol. 9, no. 12, p. 223, 2017.
View at: Publisher Site | Google Scholar
Y. Cai, J. Zhang, N. G. Chen et al., “Recent advances in anticancer activities and drug delivery systems of tannins,” Medicinal Research Reviews, vol. 37, no. 4, pp. 665–701, 2017.
View at: Publisher Site | Google Scholar
V. Lattanzio, “Phenolic compounds: introduction 50,” Nat. Prod, pp. 1543–1580, 2013.
View at: Google Scholar
P. B. Raja, A. A. Rahim, A. K. Qureshi, and K. Awang, “Green synthesis of silver nanoparticles using tannins,” Materials Science-Poland, vol. 32, no. 3, pp. 408–413, 2014.
View at: Publisher Site | Google Scholar
S. J. Bunglavan and N. Dutta, “Use of tannins as organic protectants of proteins in digestion of ruminants,” J. Livest. Sci, vol. 4, no. 1, pp. 67–77, 2013.
View at: Google Scholar
Y. H. Wang, Z. L. Wan, X. Q. Yang, J. M. Wang, J. Guo, and Y. Lin, “Colloidal complexation of zein hydrolysate with tannic acid: constructing peptides-based nanoemulsions for alga oil delivery,” Food Hydrocolloids, vol. 54, pp. 40–48, 2016.
View at: Publisher Site | Google Scholar
A. C. Adiguzel-Zengin, G. Zengin, C. Kilicarislan-Ozkan, U. Dandar, and E. Kilic, “Characterization and application of Acacia nilotica L. as an alternative vegetable tanning agent for leather processing,” Fresenius Environmental Bulletin, vol. 26, pp. 7319–7326, 2017.
View at: Google Scholar
M. Haroun, P. Khirstova, G. Abdallah, and C. Tony, Vegetable and Aluminium Combination Tannage: Aboon Alternative to Chromium in the Leather Industry, Suranaree University of Technology, Nakhon Ratchasima, Thailand, 2008.
C. A. Ezeabara, C. Faith, C. V. Ilodibia, B. O. Aziagba, O. E. Okanume, and E. I. Mbaekwe, “Comparative determination of phytochemical, proximate, and mineral compositions in various parts of Portulaca oleracea L,” Journal of Plant Sciences, vol. 2, no. 6, pp. 293–298, 2014.
View at: Publisher Site | Google Scholar
H. Fraenkel-Conrat, “The chemistry and reactivity of collagen,” Journal of the American Chemical Society, vol. 78, no. 22, p. 5960, 1956.
View at: Publisher Site | Google Scholar
A. E. Musa and G. A. Gasmelsee, “Eco-friendly vegetable combination tanning system for production of hair-on shoe upper leather,” Journal of Forest Products and Industries, vol. 2, no. 1, pp. 5–12, 2013.
View at: Google Scholar
M. K. Oladunmoye, “Effects of fermentation on nutrient enrichment of locust beans (Parkia biglobosa, Robert bam),” Research Journal of Microbiology, vol. 2, no. 2, pp. 185–189, 2007.
View at: Publisher Site | Google Scholar
L. Falcão and M. E. M. Araújo, “Tannins characterization in historic leathers by complementary analytical techniques ATR-FTIR, UV-Vis and chemical tests,” Journal of Cultural Heritage, vol. 14, no. 6, pp. 499–508, 2013.
View at: Publisher Site | Google Scholar
M. Azizi Bharudin, S. Zakaria, and C. H. Chia, “Condensed tannins from acacia mangium bark: characterization by spot tests and FTIR,” AIP Conference Proceedings, vol. 1571, no. 1, pp. 153–157, 2013.
View at: Google Scholar

Copyright

Copyright © 2023 Taame Berhanu Teklemedhin et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

PDF Download Citation

Download other formats

Order printed copies

Views

704

Downloads

368

Citations