The effect of scouring temperature on the sheep wool sorptivity

Today, synthetic fibers compete with the traditional use of sheep wool as a textile raw material, and therefore other application areas have to be sought. Due to the different functional groups on the protein side chains, the composition of wool keratin has the potential to bind various substances, thus it can work as an adsorbent. Attention is mainly focused on the removal of cations of dangerous metals because the wool has a negative overall surface charge. Almost every wool application needs clean scoured wool. The principle of the technologies used so far is scouring in a hot aqueous solution of surfactant and other additives. We developed an alternative method of scouring raw wool in an ultrasonic bath without chemicals [1, 2] based on the principle of cavitation caused by ultrasound in water. The resulting wool purity was comparable to the traditional process and fiber felting was minimized. The aim of this presented work was to examine the influence of the ultrasonic bath temperature on the adsorption capacity of the scoured sheep wool. The wool was scoured at four different temperatures (40 °C, 50 °C, 60 °C and 70 °C). After scouring, the wool samples were submitted to Cu(II) ion sorption experiments. We found that the sorptivity of wool towards Cu(II) increased slightly with increasing water bath temperature, but the differences were not statistically significant. The results show that it is sufficient to scour sheep wool in an ultrasonic bath at a temperature in the range 40–50 °C for 3 × 10 minutes. Such scouring process is more environmentally friendly, as the waste water is not contaminated with chemicals. It puts less strain on the wastewater treatment plant and can even be used to fertilize the soil. Findings from the laboratory research can be a good basis for the design of a real-life scouring line.