Determination of volatile content in coal by ultraviolet-visible-near infrared spectroscopy combined with partial least squares method
The traditional determination methods of volatile content mainly by gravimetry have some short-comings,such as poor analysis accuracy,long detection time and complicated sample pretreatment.Ultra-violet-visible-near infrared(UV-Vis-NIR)spectroscopy technology has the advantages of fast analysis speed and simple operation.It combined with chemometrics method could effectively reduce the interfer-ence of quantitative analysis accuracy of volatile content caused by the complexity of coal sample system,and achieve accurate quantitative analysis of volatile content in coal samples.The volatile contents in coal were rapidly and quantitatively analyzed by UV-Vis-NIR spectroscopy technology combined with chemo-metrics.Firstly,the spectral data of coal samples with different volatile contents were obtained by UV-Vis-NIR spectroscopy technology.Secondly,the latent variables(LVs)of partial least squares(PLS)model,the smoothing points of first derivative(1st Der),the smoothing points and polynomial order of Savitzky Golay smoothing(SG smoothing)were optimized.Finally,the modeling was conducted using three preprocessing methods and their ensemble methods,namely standard normal transformation(SNV),1st Der,and SG smoothing.Meanwhile,their impacts on the model prediction results were investigated.The results showed that the PLS correction model based on ensemble preprocessing method of SNV-1st Der-SG smoothing had the best predicting performance.When the number of LVs was 15,the determinant coefficient(R2v)for the leave-one-out cross validation(LOOCV)increased to 0.974 7,and the root-mean-square error(RMSEcv)was reduced to 1.193％.The determinant coefficient(Rp)for external verification was 0.862 5,and the root-mean-square error(RMSEp)was 2.767％.This study provided experimental and theoretical basis for the rapid and accurate analysis of coal properties and the efficient utilization of fossil fuels.
ultraviolet-visible-near infrared(UV-Vis-NIR)spectroscopypartial least squares methodvola-tilequantitative analysiscoal
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