BR-102018073077-B1 - PROCESS FOR EXTRACTING GELATIN FROM WET BLUE CHROME TANNED LEATHER WASTE

Abstract

PROCESS FOR EXTRACTING GELATIN FROM WET BLUE LEATHER WASTE. The present invention describes a gelatin extraction process from leather waste. Specifically, the present invention comprises the extraction of gelatin from wet blue leather waste by steam explosion in an alkaline medium. The present invention falls within the fields of Industrial Process Engineering and Materials Engineering.

Inventors

• CAMILA BALDASSO
• GLAITON TUZZIN
• BIANCA SANTINON SCOPEL
• ALINE DETTMER

Assignees

• FUNDAÇÃO UNIVERSIDADE DE CAXIAS DO SUL

Dates

Publication Date

20260317

Application Date

20181109

Claims (4)

1. 1. Process for extracting gelatin from wet blue chrome-tanned leather residue (WCR) characterized by comprising the following steps: a) Exposing the WCR to saturated steam at a pressure in the range of 2.5 to 4.5 bar in the presence of an alkalizing agent in a digester; b) Discharging the WCR + saturated steam + alkalizing agent into a tank at atmospheric pressure; c) Extracting, under agitation, the gelatin obtained in the previous steps with hot water, separating it from the residual solid cake by filtration.
2. 2. Process according to claim 1 characterized in that the alkalizing agent is selected from the group consisting of NaOH, MgO, Mg(OH)2 and CaO or a combination thereof.
3. 3. Process according to claim 2 characterized by comprising in step a) a residence time of 5-15 min, a saturated steam temperature in the range of 130 to 150°C, a dry basis RCCC to calcium oxide ratio of 12.5:1 and a pressure in the range of 2.5 to 4.5 bar; in step b) a water temperature in the range of 70 to 100°C; and in step c) of the process a final gelatin pH of 9.5 to 12.0.
4. 4. Process according to claim 2 characterized in that the alkalizing agent is CaO.

Description

Field of Invention [0001] The present invention describes a gelatin extraction method from wet blue leather waste. The present invention falls within the fields of Industrial Process Engineering and Materials Engineering. Background of the Invention [0002] In Brazil, according to IBGE's Quarterly Survey of Animal Slaughter, more than 2.5 million units of bovine hides are transformed into leather monthly through the tanning process. More than 80% of these tanneries employ chromium salts in their process. According to Metz (2016), in the state of Rio Grande do Sul, 44,400 tons of sawdust and wet blue leather dust are produced, a residue considered hazardous. [0003] Companies that generate this waste pay for its proper disposal or processing. In Rio Grande do Sul, this waste is mainly destined for the production of fertilizers and for landfills for hazardous solid waste (which charge approximately R$ 240.00/m3 of the waste disposed of). [0004] Among the many possible processes used for the reuse and/or disposal of chrome-tanned leather waste (CTCW) - such as fertilizers in agriculture, for the production of composite panels, its direct disposal in landfills, its thermal treatment for the recovery of chromium, activated carbon and energy - hydrolysis can be highlighted. [0005] Although conventional incineration or landfill disposal are simple methods for disposing of C&D waste, they may not be suitable due to the potential oxidation of Cr(III) to Cr(VI) (Catalina et al., 2006; Catalina et al., 2010; IULTCS 2008; Kolomaznik et al. 2008; Matyasovsky et al., 2011), since Cr(VI) can react with ions to form calcium and magnesium chromate and dichromate salts, which are carcinogenic substances. Furthermore, direct use in the fertilizer and composite panel sectors, without prior removal or reduction of chromium content, does not appear to be a more suitable alternative due to the high cost and/or environmental problems generated by this type of reuse (Cabeza et al., 1998c). [0006] The hydrolysis process not only allows the recovery of chromium, but also allows the extraction of a high value-added portion of RCCC: its protein (as hydrolyzed collagen or as gelatin). [0007] There are three types of RCCC hydrolysis: acid, alkaline, and enzymatic. Acid hydrolysis produces a liquid fraction rich in chromium and a solid cake with low chromium content (Ferreira et al., 2010). Alkaline hydrolysis allows the extraction of gelatin with low chromium content and a solid cake rich in chromium (Cabeza et al., 1998c). Enzymatic hydrolysis, in turn, is preceded by alkaline hydrolysis and can break collagen chains into chains of lower molar mass, producing hydrolyzed collagen and a solid cake rich in chromium (Cantera et al., 2002, Ocak et al., 2010). [0008] The main difference between hydrolyzed collagen and gelatin is their molar mass, which generally ranges between 15-50 kg/mol for hydrolyzed collagen and between 50-200 kg/mol for gelatin (Cabeza et al. 1998c; Catalina et al., 2006). [0009] RCCC hydrolysis has been performed for decades. However, progress in the actual industrial application of the protein obtained by this important alternative treatment of RCCC has not been seen. The costs of obtaining protein hydrolysates are not insignificant, and it seems that these high costs are the main reason for its non-implementation in industry (Mokrejs et al., 2007). [0010] The technology currently used employs alkaline hydrolysis processes in a heated medium (not exceeding 90°C) to obtain gelatin from wet blue leather waste. This hydrolysis process takes at least 2 hours, which reduces the productive capacity of facilities used for this purpose and increases process costs. [0011] Due to these facts, the development of a new method for extracting gelatin from leather waste is of interest. [0012] In the search for the state of the art in scientific and patent literature, the following documents were found that deal with the subject: [0013] The article presented at the XXXIII IULTCS Congress, 2015, by authors Laís Bavaresco, Daniele Perondi, and Aline Dettmer, entitled "Steam explosion utilization as pre-treatment of chrome leather waste in order to produce biogas," reveals a treatment of leather waste to obtain biogas. The process involves a steam explosion pretreatment, allowing the breaking of the bonds between the leather proteins and chromium. Chromium precipitation was carried out with sulfuric acid followed by the addition of sodium hydroxide. The released proteins can be exposed to microorganisms for anaerobic biodegradation, resulting in biogas. Although the article reports the use of steam explosion to break the bond between collagen and chromium, allowing subsequent biodegradation of the waste, the objective is not to extract the protein in the form of gelatin. This article did not conduct any study on the quality of the extracted protein (determining whether it was gelatin or hydrolyzed collagen). The objective of using steam e