| The concentration of formaldehyde in the computer classroom,newly decorated laboratory and simulated space in typical universities in Guilin were tested by the formaldehyde detector from March 2016 to February 2018,and the seasonal and monthly variation rules of formaldehyde concentrations and the correlation between formaldehyde concentrations and temperature or relative humidity,absolute humidity were also analyzed this study.By sifting through the organic or inorganic substances that can react with formaldehyde as scavenger agent to remove formaldehyde from wood-based panels,the effects of the type,ratio,concentration or pH value of the scavenger,and treatment temperature on the formaldehyde removal performance of the wood-based panel were investigated by using the single-factor experimental method,and the formaldehyde removal technology of wood-based panels was optimized by using the Box-Behnken Design?BBD?experimental design and response surface methodology.The results are as following:?1?The seasonal and monthly variation rules of formaldehyde concentration in the computer classroom,newly decorated laboratory and simulated space of typical universities in Guilin were almost as the same.The variation of formaldehyde concentration was basically consistent with the change trend of ambient temperature,but it has little relation with the change of relative humidity,the temperature was the main environmental factors which affecting the formaldehyde concentration.The monthly mean value and fluctuation range of formaldehyde concentrations were relatively large in summer and autumn but were relatively small in spring and winter.?2?The concentrations of formaldehyde in the computer classroom and newly decorated laboratory were positively correlated with the ambient temperature,relative humidity and absolute humidity,and were well correlated with the ambient temperature and absolute humidity,but were poorly correlated with the relative humidity.The concentrations of formaldehyde in the simulated spaces in which the density board,veneered density board,plywood and veneered plywood positioned were well positive correlated with the ambient temperature and absolute humidity,but were poorly negatively correlated with the relative humidity.?3?The maximum concentrations of the computer classroom,newly decorated laboratory and simulated space occurred in August 2016 and 2017.The maximum concentrations of the computer classroom were 0.434 mg/m3 and 0.15 mg/m3 which were 4.34 times and 1.5 times of the national standards,respectively.The maximum concentrations of the newly decorated laboratory were 0.354 mg/m3 and 0.161 mg/m3 which were 3.54 times and 1.61 times of the national standards,respectively.The maximum concentrations of the simulated space in which placed the density board,veneered density board,plywood and veneered plywood were 0.536mg/m3,1.707 mg/m3,1.346 mg/m3,5.873 mg/m3 in 2016 and 0.184 mg/m3,0.552 mg/m3,0.381mg/m3,2.85 mg/m3 in 2017,respectively.The formaldehyde concentrations in the computer classroom are still seriously exceeded the national standard after lasted eleven years.?4?When other conditions remain the same,the removal rate of formaldehyde in the wood-based panel would decrease with the increase of pH value of ammonium acetate solution,tannic acid solution,sulfanilamide solution and glucose solution,would increase first and then decrease with the increase of solution concentration such as ammonium acetate,sulfanilamide and glucose or would increase with the increase of tannic acid solution concentration,would increase first and then decrease with the increase of treated temperature such as ammonium acetate,sulfanilamide and tannic acid or would decrease with the increase of treated temperature as glucose solution.?5?When other conditions remain the same,the removal rate of formaldehyde in the wood-based panel would increase first and then decrease with the increase of pH value of sodium bisulfite and sodium carbonate solution or would decrease with the increase of p H value of sodium sulfite and ammonium bicarbonate solution,would increase first and then decrease with the increase of solution concentration such as sodium bisulfite,sodium carbonate,ammonium bicarbonate solution or would increase with the increase of sodium sulfite concentration,would increase first and then almost stable with the increase of treated temperature such as ammonium bicarbonate,sodium bisulfite and sodium sulfite or would decrease slightly with the increase of treated temperature as sodium carbonate.?6?The regress equation model of formaldehyde removal from the wood-based panels using organic scavenging agent is as following:Y=80.76+3.2A+0.58B+4.92C+0.94AB-0.99AC-3.92BC-1.06A2-9.6B2-4.4C2?R2=0.9057,P=0.0074<0.05?,compared with experimental test data,the simulation results of formaldehyde removal from the wood-based panels showed a good fit,and the maximum and mean deviation of formaldehyde removal rate between predicted and measured were 3.81%,1.96%,respectively.The regress equation model of formaldehyde removal from the wood-based panels using inorganic scavenging agent is as following:Y=93.27-1.53A-0.076B-2.85C-1.67AB+0.71AC-5.30BC-14.57A2-12.28B2-7.51C2?R2=0.9772,P<0.0001?,compared with experimental test data,the simulation results of formaldehyde removal from the wood-based panels showed a good fit,and the maximum and mean deviation of formaldehyde removal rate between predicted and measured were 2.96%,1.41%,respectively.?7?The optimum conditions for the formaldehyde removal rate from the wood-based panels using organic matters were obtained:the scavenging agent solution with a concentration of 3.88 g/L was prepared by mixing in equal volume ratios of ammonium acetate?9.98 g/L?,tannic acid?1.0 g/L?and sulfanilamide?0.646 g/L?,the pH value of the mixed solution was 6.31and the treated temperature was 294.79 K,the corresponding formaldehyde removal rate of the wood-based panel was 85.6%.The optimum conditions for the formaldehyde removal rate from the wood-based panels using inorganic matters were obtained:the scavenging agent solution with a concentration of 5.55 g/L was prepared by mixing in equal volume ratios of sodium bisulfite?4.95 g/L?,sodium sulfite?4.95 g/L?,ammonium bicarbonate?7.35 g/L?and sodium carbonate?4.95 g/L?,the pH value of the mixed solution was 5.98 and the treated temperature was 292.38 K,the corresponding formaldehyde removal rate of the wood-based panel was96.2%. |
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