Chrome Complexes in Rewetting and Neutralizing Effluents and Hints for Recycling Post-Tanning Wet-Process Effluent

Abstract

With an excellent overall performance of chrome tanned leather, the chrome tanning method is always a dominant technology in leather making. While chrome in the tanning process helps retain the strength and quality of leather, it leads to a high amount of toxic chromate ions discharged into environmental receptors after tanning [1]. The uncontrolled release of chrome in tannery effluent increases environmental pollution concerns and health risks [2]. Therefore, whatever method is used to lower the amount of chrome salts in the final discharge, it will portend chrome as a potentially toxic source to the environment [3-4]. The chrome released into the water

Influence of microwave on chromium complex composition in tanning liquor

“…Elution conditions were selected as follows: flow velocity of eluent of 2.5 mL/min, followed by using H 2 O, 0.5 mol/L NaClO 4 , 1.0 mol/L NaClO 4 , 2.0 mol/L NaClO 4 , 2.0 mol/L HCl and 2.0 mol/L HCl to elute. UV1900 UV-Vis spectrophotometer was used to detect the absorbance at 420 nm for each 7.5 mL eluent [23,24,27].…”

“…1. According to prior studies, the chromatographic peak I to peak VI represent anionic-zerovalent, monovalent, bivalent, trivalent, tetravalent and pentavalent chromium complexes respectively [23,24,27]. The contents of each composition in WB, MW and control can be calculated based on the area of ion-exchange chromatographic peaks and the results are listed in Table 1.…”

“…The different chromium complex composition should be responsible for the diversity [17][18][19][20]. Ion exchange chromatography (IEC) and gel filtration chromatography (GFC) were widely used to study the composition of chromium tanning liquor [21,22] and they also had been used to clarify chromium complex composition in leather making to provide hint for cleaner process [23,24]. Hitherto, it had been proven that microwave could promote the hydrolysis and olation chromium tanning liquor further due to existence of non-thermal effect [25,26].…”