Tanning Method Research Articles

Разработка способа прямого дубления меховых овчин

A review of the literature shows that to this day there is no consensus among researchers explaining the phenomenon of the two-bath chrome tanning method. Very high elastic-plastic properties of two-bath tanned fur with hard to imagine high strength properties compared to fur tanned using a single-bath method. There are also no convincing arguments for the practical abandonment of this method. Arguments about the bulkiness and high consumption of chemical materials, at least in today's concept of production efficiency, are not entirely convincing, because the described quality and consumer properties of fur of this type of tanning can justify high costs. A more compelling argument for rejecting the two-bath tanning method is the low heat resistance of fur, which makes it unsuitable for use where high temperature conditions are used to make products from it. Therefore, this work examines the possibility of increasing the thermal stability of semi-finished fur products. During the experiment, a semi-finished fur product with a specified heat resistance was obtained.

Extraction and Optimization of Tanning Material from Osyris lanceolata Barks: Cleaner Leather Tanning Processing

Tanning is a processing mechanism that prevents the collagen fibers from putrefaction to maximize the hydrothermal stability of leather. Tannin agents extracted from plants were used in leather production in a process called vegetable tanning. Vegetable tanning is an eco-friendly tanning method when compared to chrome tanning. Chrome tanning is the most common method of tanning hides. Currently, chrome tanning, which is extracted from chrome ores, is used in more than 80–90% of the leather tanning industry, but the most serious environmental issue associated with tanneries is chromium. This implies that the presence of chromium both in wastewater and in leather waste has a significant environmental impact and a high cost for landfills. However, currently, vegetable tanning and other tanning materials take up a 10–20% share of the leather tanning industry. Even today, most commercial vegetable tanning is a mimosa. In this study, a new alternative material and chrome-free tanning process using the barks of the Osyris lanceolata plant barks which reduces the environmental pollution load in terms of wastewater and solid wastes would be introduced. The study also aimed to improve the extraction and optimization mechanisms of tannin material from the bark of the Osyris lanceolata plant, which grows in Dera Hamusit Woreda in Ethiopia’s south Gonder Amhara region. In addition to these, the chemical and physical properties of experimentally treated leather were analyzed. This study’s results show that the bark of Osyris lanceolata contains (18.72%) tannin with 96% tanning strength (96%), and 49 percent purity. Also, leather treated with this tannin showed good shrinkage temperature (84.5°C), and organoleptic properties results such as tensile strength, tear strength, and elongation were 7.1 N/mm2, 19 N, and 45%, respectively. Besides that, the FTIR analysis shows that the bark of the Osyris lanceolata plant has a phenolic compound that is used for tanning purposes. This study clearly shows that extracted tannin from Osyris lanceolata has the potential to be used as an alternative tannin material in the leather tanning industry.

Combination tanning mechanism inspired environmentally benign catalyst for efficient degradation of tetracycline

The utilization of chelation reaction between metals and tannins is a common tanning method in leather chemistry. Herein, a novel combination tanning mechanism inspired environmentally benign catalyst (CMBT-Fe0) was synthesized by immobilizing Fe nanoparticles onto bayberry tannin (BT) grafted chitosan microfibers (CM). The obtained catalyst featured a well-defined microfibrous structure, on which Fe0 nanoparticles were highly dispersed to exhibit exceptional catalytic activity for the degradation of tetracycline (TC). The catalytic activity of CMBT-Fe0 was 1.72 times higher than that of the commercial Fe0 nanoparticles without immobilization, with 95.03% of TC degraded within 90.0 min. The CMBT-Fe0 catalysts were recycled 6 times, with the removal rate of TC maintained at 82.56%. Furthermore, a possible mechanism responsible for the catalytic removal of TC was provided by analyzing the catalytic degradation products via liquid chromatography-mass spectrometry. Therefore, our investigation successfully developed efficient catalysts to address the concerned environmental issue of antibiotic pollution.Graphical

Development of leather from the skin of yellowfin tuna (<em>Thunnus albacares</em>) and Asian sea bass (<em>Lates calcarifer</em>) using an environmentally friendly tanning technique

Yellowfin tuna (Thunnus albacares) and Asian sea bass (Lates calcarifer) are highly demanded export fish species in Sri Lanka. The objective of the present study was to prepare leather from the skin of T. albacares and L. calcarifer using tanning media prepared with black tea (Camellia sinensis) powder and table salt (NaCl). Black tea powder and table salt concentrations were increased by 10 grams (initial weight; 10 gL-1) and 1 gram (initial weight; 1 gL-1), respectively each day for 12 d. Skins were dipped in each concentration for 24 hrs. After additional water was removed, vegetableoil-applied skins were stretched and air-dried at room temperature. The percentage of ash, fat,protein, and tensile strength of the leather prepared from L. calcarifer skin was significantly higher(P<0.05) compared to leather prepared from T. albacares skin. The percentage of moisture, averagethickness, and tear strength of the leather prepared from the T. albacares skin were significantlyhigher (P<0.05) than the leather prepared from L. calcarifer skin. According to the ΔL*, Δa*, andΔb* values, leather prepared from T. albacares skin has lighter, greener, bluer and L. calcarifer skinhas darker, greener, yellower colours respectively. There are no significant colour differences betweenprepared leathers (P>0.05). Sensory evaluation results indicated that, finishing, appearance,handling, and overall acceptability, of leather wallet prepared from T. albacares has higherconsumer acceptance. The study demonstrated the effectiveness of this novel method for preparationof leather from T. albacares and L. calcarifer skin. In conclusion, T. albacares skin is more suitablefor fish leather preparation using the above described tanning method.

Characterization of materials in the late 15th-century animal encyclopedia at an Ottoman Library and detection of deterioration products by HPLC–DAD

There are many manuscripts in institutions that preserve and exhibit cultural heritage such as museums, galleries, and libraries. These manuscripts are of great value because of their witnessing to the past and the historical and cultural significance they have accumulated. In addition to the organic nature and the natural aging of the paper, which is generally used as the primary carrier material in these objects, other materials used in the manuscripts are an obstacle to their preservation and reaching future generations. In this study, the 62-volume animal encyclopedia, which is known to be written in the name of animals, plants, and Islamic science at the end of the fifteenth century (1487–1501) and added to an Ottoman Library, was examined analytically. A total of 40 samples consisting of paper, ink, dye, and leather samples were analyzed using high performance liquid chromatography with a diode array detector (HPLC–DAD). After all, information on material characterization and deterioration product(s) was obtained. As a result of the analysis, vanillic acid, and its derivatives due to the natural aging of the paper and chrysophanic acid and its derivatives caused by fungi, which are the result of unfavorable environmental factors, were determined. It was concluded that the ink used in the manuscripts was iron-gall ink. In addition, it was determined that madder, weld, buckthorn, redwood, rhubarb, or dock plants were used as dyestuffs in paper and leather samples. Also, it was deduced that the leather samples were tanned with the vegetable tanning method using tannins. Since tannic acids were determined in the dyestuff analysis of three paper samples with ink, elemental analysis was performed on black ink by scanning an electron microscope with energy-dispersive X-ray spectroscopy (SEM–EDX). As a result of this analysis, the element of iron has been detected and it has been confirmed that the black ink is iron-gall ink. It is inevitable that this study will guide conservation experts in restoration and conservation studies.

A green tanning method based on POSS-COONa and zirconium: Achieving cleaner leather production

In this study, a two-step green and clean tanning technology based on the polyhedral oligomeric silsesquioxane sodium carboxylate (POSS-COONa) and zirconium was studied to relieve the environmental pressure and resource strain caused by chrome tanning. Firstly, amino sesquisiloxane was prepared from γ-aminopropyl triethoxy silane by hydrolysis and condensation method, and then was substituted with sodium chloroacetate to form POSS-COONa. The POSS-COONa had crystallinity and maintained cube structure by X-ray Diffraction (XRD) and Transmission Electron Microscopy (TEM). Subsequently, POSS-COONa combined with zirconium sulfate was applied in tanning process of goat skin. Compared with untanning, chrome tanning, zirconium tanning crust leather, the shrinkage temperature and thickening rate of combination tanning crust leather were 90.5 °C and 118.3 %, respectively. The tensile strength, tear strength, elongation at break and softness of the combination tanning crust leather were 26.4 MPa, 96.3 N/mm, 105.5 % and 6.5 mm. The scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) showed that combination tanning crust leather collagen fibers were braided more loosely, and POSS-COONa and zirconium sulfate could be uniformly distributed in the collagen fibers. The isoelectric point of the combination tanning crust leather (∼6.7) was similar to that of chrome tanning crust leather (∼7.7). Based on the above results, POSS-COONa combined with zirconium sulfate tanning has a broad prospect in green clean production.

Reducing chromium discharge in tanning: The salt-free chrome tanning process

Nowadays, there is increasing concern about environmental protection in global industrial activities. The sustainable leather industry is currently focusing on cleaner processing methods to promote a greener environment. However, the discharge of waste streams containing several pollutants poses a significant social threat to the leather sector. The conventional pickling and chrome tanning process is particularly problematic due to the enormous amounts of chlorides and chromium emissions, which have been a longstanding issue that has not been satisfactorily resolved. In order to minimize the emissions of chromium and chloride integrately, a salt-free and high exhaustion chromium tanning method was designed and optimized. The study's results demonstrated that the chrome tanning process could be improved by conducting it in a salt-free environment, resulting in a smooth process and a chromium absorption rate increase to 99% compared to 75% in the conventional process. Moreover, the dosage of Chrome required was minimized from 1.5% to 0.8%, resulting in a significant reduction of residual Chromium concentration in the spent liquor from above 1150 mg/L to 40 mg/L. The novel chrome tanning process significantly decreases the amount of chromium-containing sludge generated and facilitates the disposal of spent liquor with a reduced amount of chrome and chloride. The novel process effectively addresses long-standing problems and meets the requirements of the modern sustainable leather industry.

Reduction of Pollutants in the Tanning Industry Using the Reverse Tanning Method against the Physical Properties of Leather

This study aims to tan the skin with reverse tanning based on the order of pH, thereby reducing the use of chemicals and water due to the pH regulation process. The reverse tanning method will result in a faster tanning process and reduce the use of many chemicals, so that the pollutant load released from the tanning process will be much reduced. Conventional leather tanning is carried out through many processes starting from the BHO (Beam House Operation) process, tanning, post-tanning, and finishing; this process is carried out through a 14-15 step process that produces a large number of pollutants. This is because in conventional leather processing a lot of pH adjustment processes are carried out that go back and forth. In this study the leather processing steps were ordered based on the pH of the tanning process, the chemicals and the pH of the process were regulated by the sequence of the process steps to avoid some repeated acidification and basification/neutralization as in conventional leather processing. The process begins with soaking, liming, fleshing, deliming, tanning, dyeing, fatliquoring, and chrome tanning. This process begins with an alkaline pH of 11 and ends with an acidic pH of 3.8. Chrome tanning is done with variations in the amount of chrome of 2%, 3%, 4%. The results showed that leather with 4% chromium produced the highest Ts of 103 °C, tensile strength of 39.86 N, tearing strength of 13.19 N/mm, seam strength of 12.8 N/mm, elongation of 46.87%, Cr content (VI) 1.68 ppm. These results have met the standard ISO/TR 20879:2007 Footwear. The reverse tanning process with a process from high to low pH without adjusting the pH back and forth by adding solutions and salts means reducing liquid waste in the leather tanning process. So, this process can reduce the amount of liquid waste or pollutants.

Sustainable biomass as green and efficient crosslinkers of collagen: Case of by-products from six pomegranate varieties with global commercial interest in Morocco

Chrome tanning is the most common method used to produce leather, but its environmental and health impacts have necessitated the search for alternatives that have proved to be challenging. The circular economy, which uses biomasses to reduce and recover waste, is seen as a potential solution. In Morocco, fruit waste produced by juice processing industries is an untapped source of tannins that could replace chrome tanning in a more sustainable manner. In this study, a new eco-friendly tanning method based on vegetable biomass has been developed to reduce chromium-related environmental pollution and enhance leather performance. Tanning activities of extracts from six Moroccan pomegranate rind (PR) varieties were investigated, by studying their crosslinking with the insoluble collagen (IC) extracted from a sheep hide, under industrial tanning conditions. Herein, molecular distribution of crosslinkers extracts were carried out using gel exclusion chromatography to follow polymerization degree and crosslinking kinetics during tanning process. Between linear and logarithmic profiles, tannins and phenolics behave differently during the crosslinking depending on their molecular weight. Fourier Transform Infrared Spectroscopy exhibits the existence of inter and intramolecular interaction between IC functional groups and extract. X-Ray Diffraction analysis shows the influence of crosslinkers extracts into the triple helix structure of collagen. Scanning Electron Microscopy observations shows the fibrial size variations of crosslinked collagenous structure by varying the extract variety. Differential Scanning Calorimetry and thermogravimetric measurements revealed that the thermal stabilities were affected by the extracts varieties origins. Theoretical studies using Gaussian was used as a complementally tool to compare the reactivity and the stability of the major molecules that contributes in the crosslinking process. Principal Component Analysis (PCA) was used to examine correlations between the crosslinked IC and PR extracts' analyzed properties. The data set's dimension was reduced to two components via PCA, which accounted for 69.79% of the observed variability.

EFISIENSI PENGGUNAAN AIR DAN KROM PADA PROSES TANNING SHEEP CABRETTA MENGGUNAKAN METODE EXHAUSTED TANNING CHROME

This study aims to make chromium and water more efficient in the tanning process. The methods used include water efficiency from 100% to 50% and chromium reduction from 6% to 4% using exhausted chrome tanning method. The raw material used is grade 6 pikel sheepskin and the auxiliary chemical used is acrylic copolymer. The tests carried out were organoleptic, physical and chromium content in the waste. Organoleptic and physical tests showed that the condition of slackness, and the suitability of color on the crust of the pearl white cabretta article had met consumer purchasing standards. In the results of physical testing of samples using the exhausted chrome tanning method, almost all of them meet the test standards from SII-0943-84. Waste testing showed that the use of the efficiency method had a significant decrease in the amount of total chromium, from 757.35 mg/L to 487.80 mg/L.

The effect of pH and tanning agents on the quality of sheep leather using the ecoprinting dyeing method

Leather eco-printing is an eco-friendly dyeing technique performed by transferring colors from plants. Therefore, this study aims to investigate the effect of pH and tanning agents on the quality of sheep leather using eco-printing dyeing method to produce an eco-friendly animal product. A total of 30 sheep crust leather were randomly assigned using a 2 × 5 factorial arrangement, with three replications. The first factor was the leather tanning agent namely vegetable and mineral, while the second was pH of 5, 6, 7, 8, and 9. The plants used in eco-printing were Kenikir (Cosmos caudatus) leaves, Kenikir flowers, Jatropha (Jatropha curcas) leaves, Ganitri (Elaeocarpus ganitrus) leaves, Ferns (Pteridophyta) leaves, Lanang (Oroxylum indicium) leaves and Teak (Tectona grandis) leaves. Color sharpness and fastness data were collected and then analyzed using a two-way analysis of variance followed by Duncan’s Multiple Range Test. The results showed interactions between the tanning method and pH (P = 0.01) on color sharpness, with the highest values produced in mineral leather processed under pH 9. Mineral leather had higher color sharpness and fastness values with P < 0.05 compared to vegetables. Furthermore, the pH significantly affected sharpness (P < 0.01) but had no effect on colorfastness. Based on the results, the combination of mineral tanning with a pH of 9 can be applied for eco-printing to produce the best sheep leather product.

A chrome-free combination tanning strategy: based on silicic acid and plant tannin

Silicic acid, commonly derived from cheap and easily available sodium silicate, has recently received great attention for application in leather industry to produce ecological leather with a cleaner approach. However, leather tanned with silicic acid alone is poor in storage stability, which limits its practical application in leather production. In this work, a new environment-friendly combination tannage based on silicic acid and plant tannin was developed to address this issue along with improving the comprehensive performances of leather. The obtained leather was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and so on. The results showed that compared with leather tanned with silicic acid alone, the leather tanned with this combination method possessed improved thermal stability, enhanced mechanical properties, acceptable softness, appropriate hydrophilicity, and especially enhanced storage stability. More importantly, the combination tanned leather with 1:1 of the mass ratio of silicic acid to vegetable tannin (composed of valonea extract and mimosa extract with the same weight) had more prominent comprehensive performances. In addition, the results demonstrated that hydrogen bonding played an important role in the combination tanning process. Furthermore, the hydrogen bonds generated between phenolic hydroxyl groups of polyphenols with silicon hydroxyl groups of silicic acid molecules inhibited the excessive condensation of Si-OH groups between themselves. Subsequently, the assessment of environmental impact revealed the value of BOD5/COD of the wastewater produced in this combination tanning process is more than 0.3, indicating the chrome-free combination tannage based on silicic acid and plant tannin was an environment-friendly tanning technology. These findings therefore indicated that a new chrome-free tanning method with silicon and biomass materials as main tanning agents has potential practical application prospect in leather production.Graphical abstract

Preparation and Application of Modified Montmorillonite Dispersion for Chrome-less Tanning of Leather

The properties of modified montmorillonite dispersions for their use in the chrome-less leather tanning method were investigated. It is proposed to modify montmorillonite with aluminum compounds and to combine the obtained dispersions with chromium compounds for leather treatment. Modification of montmorillonite dispersions by aluminum compound within 5.0-7.0% Al2O3 of the weight of the mineral contributes to obtaining the most stable positively charged montmorillonite dispersions. The use of the obtained montmorillonite dispersions is effective for stabilizing the collagen structure and increasing the temperature resistance of collagen. The use of modified montmorillonite dispersions combined with a chromium tanning agent contributes to the introduction of chrome-less tanning. 0.75% of Сr2O3 and 3.0% of modified dispersion of montmorillonite of the weight of the pelts in conversion for mineral weight are considered the optimal consumption of chromium tanning agent.

An Environmentally Friendly Mineral-Free Tanning of Animal Skins – Sustainable Approach with Plant Resources

An eco-friendly mineral-free process for tanning has been developed in the present investigation, which is based on replenishable plant resources. Significant reduction in total dissolved solids and chlorides compared to conventional tanning method was observed in the new process. Tara and jatropha seed oil were employed for tanning of animal skins. The thermal and morphological characteristics, resistance to fungal and organoleptic properties of the tanned leathers were analyzed by using shrinkage, differential scanning calorimetric and thermo-mechanical analysis techniques. It has been proved that the properties of the tanned leathers are better than that of conventional vegetable tanned and comparable to chrome tanned leathers. The cross section of fibre structure indicates uniform structure and fibre bundles seem to be less dispersed when analyzed through scanning electron microscope. The tanned leathers exhibited better physico-chemical and organoleptic properties. The new tanning system also exhibited cost advantages due to reduction in chemicals consumption and savings due to reduced effluent treatment costs. The developed tanning process reduces the generation of toxic waste compared to mineral tannages, which reduces the environmental impacts. Hence, this techno-commercial study provided a viable and versatile solution for mineral-free tanning for commercially sustainable processing through cleaner process options.

A rapid and cleaner chrome tanning technology based on ultrasound and microwave

Abstract At present, chrome tanning had irreplaceable advantages and was still the dominant tanning method in leather making, thus more and more attention should be paid to minimizing chrome-containing effluent discharging during tanning with some new techniques. In this work, a rapid and clean chrome tanning method based on wringing, ultrasound and microwave was developed for cleaner chrome tanning. In the new method, chrome tanning agent could penetrate into leather within 6 min because of the synergistic effect of capillary generated by wringing and cavitation resulted from ultrasound, and the tanning could finish without basification by using microwave irradiating well-penetrated leather for 5 min. The total time for one complete tanning was only 11 min, while it takes 8–12 h or longer to finish this process with traditional method. On aspects of the leather properties tanned by the new method, the chrome content, thermal stability and chrome distribution uniformity of the wet blue were slight poorer than traditional, but the mechanical properties, organoleptic properties and collagen fiber inter-woven structure were comparable. Moreover, the leather properties kept stable during continuous tanning for 10 times. Since there was no additional substance added into the system, the tanning liquor in the method might be recycled by replenishing corresponding materials according to analysis. In sum, since the innovative tanning method has an outstanding features of rapid tanning with almost zero chrome-containing wastewater discharging, it would be a new potential routine for cleaner chrome tanning in future.

Electrochemically Enhanced Processes for Leather Tanning

Leather production involves several operations where the tanning plays the major role in improving the durability of leather products by forming durable linkages between the tanning agents and the collagen. Different agents are used, but the most important is chromium. However, nowadays there is a growing demand for a cleaner, but still effective alternative for production processes. In the traditional tanning process, the penetration of these agents inside the leather is governed by diffusion based on a concentration gradient. In this study, a new tanning approach is proposed, taking advantage of the intensification effects of an applied electric field, within two electrodes in solution, on the tanning method [1]. An improvement in the efficiency is observed due to the positive charge acquired by the agents (Cr, Ti, Zr and Fe) complexes in tanning solutions and the possibility to control the bath pH by exploiting the side reactions at the two electrodes. The new electrochemically intensified tanning technique shows better performances than the standard one, resulting in a larger agent uptake in the same amount of time, leading to a shorter process time. The intensification of the tanning process will be justified in light of a simulation model of the involved phenomena. Enhanced chrome tanning process, Patent Pending

Mechanical Blending Preparation of Hydrophilic Spherical Nano-SiO2/Acrylic Resin Nanocomposite for Tanning Leather

In this study, the spherical silica nanoparticles (denoted as PASP-K-SiO2) were firstly prepared with 3-aminopropyltriethoxy silane (KH550) and polyaspartic acid (PASP) as surface-modifiers by sol–gel method. The PASP-K-SiO2 nanoparticles were well dispersed in water and combined with waterborne acrylic resin matrix (denoted as PAA) for preparing novel nanocomposite tanning agents (denoted as PASP-K-SiO2/PAA) successfully through a strong mechanical blending. The nanocomposite tanning agents were used to tan pickling white-wet sheepskin and the tanned leather was characterized by rheological measurements, revealing an increase in the storage modulus and relaxation time of the leather compared to the leather tanned with bare nano-SiO2 and neat PAA. The leather tanned with PASP-K-SiO2 nanoparticles also exhibits excellent mechanical properties, high thermal stability and chromium absorption rate. Moreover, the shrinkage temperature of the leather tanned with PASP-K-SiO2/PAA and just 0.2% chromium powder based on the sheepskin weight can reach above 80 C, which is potentially advantageous in completely or partially replacing toxic chromium tanning agents used in traditional leather industry. Compared with the chromium tanning process, the tanning method with the nanocomposites would be regarded as eco-friendly, thus contributing to the reduction of environmental impact.

A novel chrome-free tanning approach based on sulfonated tetraphenyl Calix[4]resorcinarene: Preparation and application

Chrome tannage is the main tanning method because of its excellent hydrothermal stability and physical performances. However, the chromium absorption is limited, so the emissions of solid wastes can bring many environmental issues and human health risks. Therefore, a novel chrome-free tanning agent based on a water-soluble calixarene has been attempted. Water-soluble calixarene is a chemical with a unique molecular structure, thermal stability and high chemical stability, it contains a lot of more active coordination of phenolic hydroxyl. In this work, tetraphenyl calix [4]resorcinarene (TC4R) was synthesized with one-step process, and then was sulfonated by concentrated sulfuric acid, which obtained the sulfonated tetraphenyl calix [4]resorcinarene (STC4R). The chemical structure of the TC4R and STC4R were detected by IR and H-NMR. Then STC4R was added to the tanning process as an experimental process and 6% conventional chrome tannage was added to tanning as control. The result shows that the Ts of tanned leather is 77.2 °C using 10% STC4R at final pH 4.0. SEM analyses show that collagen fibers have been dispersed, STC4R makes the fiber loosen and the fullness is increased. FT-IR shows that the hydrogen bond is formed between phenol hydroxyl of sulfonated calixarenes and amino of collagen in the tanning process. At the same time, STC4R does not enter the micro fibrils within the collagen, so three helix structures are not damaged and consistent with AFM.

A Chromium Discharge Minimizing Tanning Technology Assisted by O2 Low Temperature Plasma

Substantial quantities of solid and liquid wastes generate in the chrome tanning process, posing major environmental problem if not managed effectively. In order to minimize the emissions of chromium, a high exhaustion chromium tanning method was designed in this study. Low temperature plasma (LTP) technology has the characteristics of economy, pollution-free and high efficiency. The pioneering works were carried out by applying LTP to surface modification of natural leather before tanning process. The effects of different treatment time on micro-structure, chemical compositions, active groups, tanning absorption rate of leather fiber were studied. The SEM results showed that the leather surface was etched rougher. The XPS data showed that the O1s area ratios increased from 18.8 % to 27.6 % after O2 LTP treatment. The optimal O2 plasma treatment time is 10min. The results show O2 LTP treatment effectively improves the chrome tanning absorption rate from 78.68 % of conventional process to 94.47 % of the novel process, which reduces the emission of heavy metal chromium and protects the environment.

Modeling of Cr contamination in the agricultural lands of three villages near the leather industry in Kasur, Pakistan, using statistical and GIS techniques.

Kasur is one of the hubs of leather industry in the Punjab, Pakistan, where chrome tanning method of leather processing is extensively being used. Chromium (Cr) accumulation levels in the irrigation water, soil, and seasonal vegetables were studied in three villages located in the vicinity of wastewater treatment plant and solid waste dumping site operated by the Kasur Tanneries Waste Management Agency (KTWMA). The data was interpreted using analysis of variance (ANOVA), clustering analysis (CA), and principal component analysis (PCA). Interpolated surface maps for Cr were generated using the actual data obtained for the 30 sampling sites in each of the three villages for irrigation water, soil, and seasonal vegetables. The level of contamination in the three villages was directly proportional to their distance from KTWMA wastewater treatment plant and the direction of water runoff. The highest level of Cr contamination in soil (mgkg-1) was observed at Faqeeria Wala (37.67), intermediate at Dollay Wala (30.33), and the least in Maan (25.16). A gradational variation in Cr accumulation was observed in the three villages from contaminated wastewater having the least contamination level (2.02-4.40mgL-1), to soil (25.16-37.67mgkg-1), and ultimately in the seasonal vegetable crops (156.67-248.33mgkg-1) cultivated in the region, having the highest level of Cr contamination above the permissible limit. The model used not only predicted the current situation of Cr contamination in the three villages but also indicated the trend of magnification of Cr contamination from irrigation water to soil and to the base of the food chain. Among the multiple causes of Cr contamination of vegetables, soil irrigation with contaminated groundwater was observed to be the dominant one.