Figures (3)  Tables (1)

    • Figure 1. 

      Variation of coconut-husk biochar properties with different pyrolysis temperatures.(a) Biochar yield. (b) Variation of biochar-C content. (c) Variation of biochar-O content. (d) Variation of biochar-N content. (e) Variation of biochar-P content. (f) Variation of biochar-K content. (g) Variation of biochar-Na content. (h) Variation of biochar-Ca content. (i) Variation of biochar-Mg content. (j) Variation of biochar-S content. (k) Variation of biochar-Cl content. (l) Variation of biochar-Si content. Means with different letters represent significant differences at p < 0.05 level.

    • Figure 2. 

      Graphical display of the correlation matrix, using the 'corrplot' package of R-software. Red color indicates the negative correlations between shown variables; blue color indicates the positive correlations; white color indicates no correlation. The areas of the squares show the absolute value of corresponding correlation coefficients. Parameters covered by blue lines show similar correlation variation patterns.

    • Figure 3. 

      Scanning Electron Microscopy (SEM) micrographs of coconut-husk biochar produced at 400 °C. (a) Under 3.00 K X of magnification. (b) Under 1.00 K X of magnification. (c) Under 500 X of magnification. (d) Under 250 X of magnification. (e) Under 100 X of magnification.

    • Pyrolysis temperature (°C)O/C ratio of coconut-husk biochar
      3250.49
      3500.46
      4000.32
      5000.22
      6000.08
      7000.10

      Table 1. 

      Variation of O/C ratio at different pyrolysis temperatures.