4.2.5. Leather industry waste
The feasibility of leather industry solid waste was evaluated
as an adsorbent for removal of Cr(VI) and As(V) from aqueous
media [299]. The high amounts of Cr(VI)-133 mg/g and As(V)-
26 mg/g adsorbed demonstrated the great potential for using this
solid waste from the leather industry as a low-cost alternative to
the traditionally used adsorbent materials. Fleshing from animal
hides/skins, another waste from leather industry, is high in protein
content. Raw fleshing has been complexed with iron and is
used for the removal of chromium(VI) [300]. Iron treatment greatly
improved adsorption of the fleshing for hexavalent chromium.
The ultimate adsorption capacity of iron treated fleshing was
51 mg of chromium(VI) per gram of fleshing. The sorption capacity
of untreated fleshing was 9 mg/g indicating that iron treatment
significantly increased the adsorption capacity of fleshing. The
adsorption kinetics was well described by pseudo-second-order
kinetic model. X-ray photoelectron spectroscopic (XPS) studies
showed that the iron was incorporated into the protein matrix.
Shifts in XPS spectra suggested that dichromate binding occurred
with iron at active adsorption sites and that iron treated fleshing
removed chromium(VI) without reducing it to chromium(III)