Intumescent fire retardant coating with recycled powder from industrial effluent optimized using response surface methodology

With the rapid development of Al electrolytic capacitors, plenty of industrial effluents are generated during the corrosion process of aluminium anode, resulting in serious environmental problems. To address such a challenging but urgent issue, we recycle powders containing lots of flame-retardant compositions from the precipitate of industrial effluents and apply them in the intumescent fire retardant coating. The formula of coating is optimized using response surface methodology based on central composite design. Under the optimum formula (APP: 60 wt%, PER: 19 wt%, MEL: 18 wt%, and the recycled powder: 9 wt%), the optimal sample is prepared and its fire resistance is investigated in our lab. During the fire resistance test, this sample displays the lowest backside temperature (only 163 degrees C) among all samples, indicating superior fire retardancy. In addition to fire resistance analysis, the water resistance and thermal stability of intumescent fire retardant coatings are also characterized. Our results show that the water contact angle and char yield of optimal sample reach up to 78.9 degrees and 30.1 %, respectively. Thus, the optimal coating features superior fire retardancy, excellent water resistance and outstanding thermal stability. This work offers a practical strategy for creating a high-performance intumescent fire retardant coating based on the reuse of industrial effluent, which is favorable to environment protection and has a promising future in the industry.