Study On Removal Of4-chloro-3,5-dimethylphenol By Adsorption With Bamboo-carbon And Catalytic Ozonation With Iron-scraps

The phenols discharged to the environment increase the mortality of aquatic life and microorganisms at low concentrations. Of these compounds,4-chloro-3,5-dimethylphenol (PCMX) has been listed as priority pollutants by American Environment Protection Agency (EPA) and Chinene Ministry of Environmental Protection.In the present work, degradation of PCMX by adsorption using bamboo-carbon and catalytic ozonation with iron-scraps was investigated, respectively. Dynamics and a possiable degradation mechanism was proposed.To evaluate the adsorption performance of PCMX in aqueous solution on bamboo-carbon, several operating variables, including particle size of bamboo-carbon, bamboo-carbon dosage, rotation rate, and temperature, were studied. The results showed that, the high PCMX absorption capacity of bamboo-carbon due to its high specific surface areas (552.8m2/g) and total pore volume (～0.35cm3/g) with the particle size of0.6-0.9mm. Under the best conditions such as bamboo-carbon particle size of0.6-0.9mm, bamboo-carbon dosage of4.0g/L, rotation rate of150r/min, initial PCMX concentration of50mg/L and temperature of20℃, after2h reaction, the removal efficiency of PCMX was97.6%.Moreover, the operational parameters and mechanism of PCMX were investigated using catalytic ozonation with iron-scraps as catalyst. The results showed that catalytic ozonation with iron-scraps for removal of total organic carbon (TOC) of aqueous solution containing PCMX is more efficient than ozonation alone or interior microelectrolysis with iron-scraps alone. Besides, this paper first introduced the implementation method of solid-liquid separation technology by hunging a filter bag filled with iron scraps in the middle of the glass reactor. With the initial pH of3.0, the initial PCMX concentration of50mg/L, the iron scraps dosage of62.5mg/L, the ozone dose of2.2g/h, the removal of TOC values reaches86.6%after3h reaction, indicating the micro-electrolysis/ozone oxidation of PCMX simulated wastewater is significantly effective.A tentative degradation pathway was proposed without any further quantitative analyses. During the degradation, all nitrogen atoms and phenyl groups of Direct Red23were degraded into urea, nitrate ion, nitrogen and formic, acetic and oxalic acids, etc.Additionally, based on the major aromatic intermediates identified by GC-MS spectrometry, the intermediates including anthracene-9,10-dione, maleic acid and oxalic acid, etc., were detected, and a tentative degradation pathway of PCMX was proposed.