resumo
The raw materials for the tanning industry, namely hides and skins, are preserved (curing stage) and carried with common salt, i.e., sodium chloride (NaCl). Proceeding to conversion into leather, pickling is a key stage of the tannery process, which entails high demand of water and salt. In this work, the salt-derived brine (SdB) generated from the curing of hides was treated by iron-driven electrocoagulation (EC), aiming at its later application in the pickling stage of the tanning industry, promoting a transition to zero waste emission policy. Focusing on reducing the brine's total organic carbon (TOC), central composite rotational design and response surface methodology were adopted to study the effect of electrolysis time (6.2-14.2 min) and current density (74-431 A center dot m(-2)) on the treatment of the SdB (similar or equal to 7.5 % wt. NaCl). The quality of the treated brines was then assessed in pickling trials and compared with virgin brine. 68-83 % removal of TOC from the SdB were achieved under electrolysis time ranging 6.2-14.2 min and current density ranging 126-252 A center dot m(-2). Under these operating ranges the quality of the wet-blue leathers was guaranteed. Lowest power consumption (0.44 kWh center dot m(-3)) was achieved under electrolysis time of 6 min and current density of 126 A center dot m (-2), yielding 68 % removal of TOC. Moreover, the shrinkage temperature of the hides was improved with treated brine (103.5 degrees C-110.5 degrees C) compared to virgin brine (103.0 degrees C). The present study provides strong evidence that contaminated salt from the curing stage can be valorised within the tanning industry through electrocoagulation treatment and then used in another production stage, instead of being landfilled.
palavras-chave
WASTE-WATER; ELECTROCHEMICAL OXIDATION; PROCESS OPTIMIZATION
categoria
Environmental Sciences & Ecology; Public, Environmental & Occupational Health
autores
Sarinho, L; Carvalho, P; Patoilo, D; Ribeiro, JP; da Cruz, JB; Gaiao, J; Marques, C; Nunes, MI
nossos autores
João Peres Ribeiro
Investigador Júnior
Pedro J. Carvalho
Professor AuxiliarProjectos
Inovação na produção de subprodutos salinos em simbiose industrial (SIMBIOSALT)
Collaboratory for Emerging Technologies, CoLab (EMERGING TECHNOLOGIES)
CICECO - Aveiro Institute of Materials (UIDB/50011/2020)
CICECO - Aveiro Institute of Materials (UIDP/50011/2020)
Associated Laboratory CICECO-Aveiro Institute of Materials (LA/P/0006/2020)
agradecimentos
This work is financed by Portugal (2020) through European Regional Development Fund (ERDF) in the frame of CENTRO2020 in the scope of the project SimBioSalt, CENTRO-01-0247-FEDER-069712. The work was developed within the scope of the project CICECO - Aveiro Institute of Materials, UIDB/50011/2020 + UIDP/50011/2020 + LA/P/0006/2020, financed by national funds through the FCT/MEC (PIDDAC) and CESAM (UIDP/50017/2020 + UIDB/50017/2020 + LA/P/0094/2020) , financed by national funds through the FCT/MCTES. J.P. Ribeiro and C. Marques acknowledges FCT for their PhD Grant (SFRH/BD/141133/2018) and (BD/08959/2021) , respectively.