The co-pyrolysis of waste urea-formaldehyde resin with pine sawdust: co-pyrolysis behavior, pyrocarbon and its adsorption performance for Cr (VI)

Urea-formaldehyde (UF) resin is difficult to degrade and classified as hazardous organic waste. To address this concern, the co-pyrolysis behavior of UF resin with pine sawdust (PS) was studied, and the adsorption properties of pyrocarbon were evaluated with Cr (VI). Thermogravimetric analysis revealed that adding a small amount of PS can improve the pyrolysis behavior of UF resin. Based on the Flynn Wall Ozawa (FWO) method, the kinetics and activation energy values were estimated. It was observed that when the amount of UF resin exceeded twice that of PS, the activation energy of the reaction decreased, and they acted synergistically. The characterization of pyrocarbon samples showed that the specific surface area increased with the increase of temperature, while the content of functional groups showed the opposite trend. Intermittent adsorption experiments showed that 5UF + PS400 achieved 95% removal of 50 mg/L Cr (VI) at 0.6 g/L dosage and at pH 2. The adsorption process was consistent with the Langmuir isotherm and pseudo-second-order kinetics, and the maximum adsorption was 143.66 mg/g at 30 celcius. Furthermore, the adsorption process consisted of electrostatic adsorption, chelation, and redox reaction. Overall, this study provides a useful reference for the co-pyrolysis of UF resin and the adsorption capacity of pyrocarbon.

Automated summary

This study investigated the co-pyrolysis behavior of UF resin and PS as well as the adsorption properties of pyrocarbon for Cr (VI). Thermogravimetric analysis showed that the addition of PS improved the pyrolysis behavior of UF resin. The kinetics and activation energy values were estimated using the FWO method, and it was found that UF resin and PS acted synergistically when UF resin exceeded twice the amount of PS. The adsorption experiments demonstrated that 5UF + PS400 achieved 95% removal of 50 mg/L Cr (VI) at 0.6 g/L dosage and pH 2. The adsorption process followed the Langmuir isotherm and pseudo-second-order kinetics, and the maximum adsorption capacity was 143.66 mg/g at 30 degrees Celsius. The adsorption process involved electrostatic adsorption, chelation, and redox reaction. Overall, this study provides valuable insights into the co-pyrolysis of UF resin and the adsorption capacity of pyrocarbon.