Temperature effect on an ultrasound-assisted paper de-inking process.

Area of Science:

• Environmental Science
• Materials Science
• Chemical Engineering

Background:

• Ink removal from recycled paper is crucial for sustainability.
• Ultrasound-assisted processes offer a promising eco-friendly alternative for de-inking.
• Understanding the influence of process parameters like temperature is key to optimizing efficiency.

Purpose of the Study:

• To investigate the effect of temperature on ultrasound-assisted ink removal from paper.
• To determine the optimal temperature for maximizing ink removal efficiency.
• To elucidate the chemical changes occurring in the ink during sonication.

Main Methods:

• White copy paper was soaked in black ink and dried.
• Ink removal was performed using ultrasound under varying temperatures (15-45°C).
• Results were assessed by UV-vis absorbance of the aqueous phase and paper brightness measurements.
• Inductively coupled plasma analysis was used to identify ink components.

Main Results:

• Ultrasound-assisted de-inking improved paper brightness between 15-45°C, with an optimum at 35°C.
• UV-vis spectroscopy indicated chemical modification of desorbed ink, suggesting sonodegradation.
• Ink not absorbed on paper did not undergo similar chemical changes.
• Inductively coupled plasma analysis confirmed that metal components remained on the paper, while organic components were released and altered.

Conclusions:

• Temperature plays a critical role in the efficiency of ultrasound-assisted ink removal.
• The optimal temperature for this de-inking process is 35°C.
• Sonication selectively degrades the organic components of the ink released from the paper, while metal-binding components remain adsorbed.