Leather tanning mainly depends on chrome tanning. A huge amount of basic chromium sulfate (BCS) is used in leather tanning. About 60–70% of BCS has been taken by leather and the rest of the amount is discharged as effluent and solid waste. In the Common Effluent Treatment Plant (CETP) of BSCIC Tannery Industrial Estate (Hemayetpur, Savar, Dhaka), the effluent which contained a high concentration of chromium is precipitated as solid chromium hydroxide with other elements which is called a chrome cake. Chrome cake is not exposed directly in the open space due to its toxic effect on human health as well as the environment. Human occupational experience distinctly indicates that, when inhaled, chromium compounds are respiratory tract irritants, resulting in airway irritation, airway obstruction, and lung, nasal, or sinus cancer. It is strongly suggested to extract Cr from the chrome cake before dumping it; otherwise, it will be a potential hazard to the environment. Herein, the chrome cake is characterized by inductively coupled plasma-optical emission spectroscopy (ICP-OES), X-ray fluorescence (XRF), UV-visible spectrophotometer, etc., and develops a method to separate chromium from chrome cake. ICP-OES and XRF analyses show that the total chromium contained in chrome cake is ∼17.45% and 20.7%, respectively. UV-visible spectrophotometer indicates that ∼0.04% of chromium is hexavalent. Afterward, chromium has been separated by using H2SO4 where the optimized concentration was found to be 7%. The separation efficiency of chromium from the chrome cake for optimized condition is obtained at ∼95%.
Curing of hides and skins using sodium salt is a well-established and economical preservation technique worldwide. But it contributes to generating a large amount of total dissolved solids (TDS) and increasing the salinity of water during leather processing which is a threat to the environment. The current research is an attempt to preserve goat skin using mahogany (Swietenia mahogany) seed’s extract. In real practice different percentages of mahogany seed extract were applied on raw goat skin and 3% (by weight of skin) of it showed best result. To evaluate the preservation efficiency, related parameters of preservation viz. odor, hair slip, shrinkage temperature, moisture content, bacterial count etc. were monitored regularly for 30 days. The obtained results were compared with conventional salt curing process. The experimental trial showed efficiency in lessening TDS value and chloride content. The preserved goat skins of both trials were treated following conventional leather processing techniques and physical properties were studied. The discussed preservation method exhibited comparable result in every index.
After a certain period or end-of-life (EoL), all the valuable products become waste if they are not properly managed. This study reveals the appropriate and sustainable pathway to manage the various solid wastes coming from used footwear (boots) of the Bangladesh Armed Forces and other Forces. The major parts separated from the collected four pair of used boots include leather, thermoplastic rubber (TPR) materials (e.g., sole, toe puff, stiffener, etc.), laces, metal shank, metal eyelet, etc. Careful observation of the used boots and its separated parts indicated 92-96% damage of the boots after the use of the boots for six months. Based on the properties of different parts of used boots, an integrated 4R’s waste management (reuse, recycle, recovery, and reduce) concept was introduced. It helps to minimize greenhouse gas, smog, heavy metals, dyes, pigments, and other pollutants emission to the atmosphere, thereby reducing the severe health consequences, environmental pollution, and climate change. This paper also discusses the critical aspects of various materials obtained from the post-consumer used boot through different mechanical, thermochemical, and chemical treatment processes.
Researchers around the world are in continuous endeavor to develop environment friendly tanning agent due to adverse effect of conventionally used chromium during leather tanning. Recent trend of tanning is thus heading to chrome-free and greener chemical processing options. Vegetable tanning is an exoteric leather processing technique because of their lower pollution load on the environment. Considering the inadequacy and high costing for the commercialized tannins, development of alternative tannins from locally available plants and their characterizations are important. In this research, the stem barks of Trema Orientalis (L.) were extracted at different temperatures employing water solvent with or without additives (sodium hydroxide or sodium sulphite) to attain phenolic-rich extractives. To ascertain appropriateness as a vegetable tanning agent, the obtained extracts were thereafter characterized in respect to yield, total phenolic content, tannin content and molecular structure. The extraction yield for all extracts improves and the quality remains nearly unchanged with temperature rising. The elevated concentration of chemical additives enhances the extraction yield but lessens the quality of extracts. In terms of extraction yield and the quality of extracts the best condition for extraction was discerned at 80°C with water solvent. This water extract has a decent extent of phenolic and tannin content of 266.13 mg Gallic acid equivalent/ gm of dry extract and 30.12 % respectively. The final extract exhibits excellent leather retanning tendency comparable to the commercial quebracho tannins.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.