Table 2.

Multilinear regression model for heavy metal detoxification by organic acids.

HM	Model building	R-sq %	Final model Equation
Cd	X1:Oxalic acid X2:Malonic acid X3:Malic acid X4:Lactic acid X5:Citric acid	67.86	=14.87–2.040 X1+ 5.60 X2 + 2.03 X3-1.623 X4- 5.53 X5- 0.1086 X2^2- 0.1286 X3^2 + 0.1205 X1*X5 + 0.1583 X4*X5
Cr	X1:Oxalic acid X2:Propionic acid X3:Malic acid X4:Lactic acid X5:Maleic acid	71.58	=−0.011 + 0.0936 X1- 0.0319 ×2 + 0.197 X3- 0.0756 X4- 0.01491 X1*X3 + 0.00654 X2*X4
Hg	X1:Oxalic acid X2:Malonic acid X3:Succinic acid X4:Bütyric acid X5:Citric acid	98.72	=−0.00678 + 0.000924 X1- 0.00263 ×2 + 0.001110 X3 + 0.00985 X4 + 0.00278 X5 + 0.000413 X4^- 0.000417 X2*X4 + 0.000584 X2*X5 – 0.000905 X4*X5
Pb	X1:Oxalic acid X2:Malonic acid X3:Succinic acid X4: Malic acidX5: Citric acid	98.23	=16.54–0.461 ×1+ 4.406 X2- 0.584 X3- 1.224 X4- 3.747 ×5 + 0.0842 X1^2- 0.06360 X2^2- 0.1083 X4^2 + 0.0692 X5^2- 0.0746 X1*X2 + 0.1004 X3*X4 + 0.0635 X4*X5
Ni	X1:Oxalic acid X2:Malonic acid X3:Succinic acid X4:Malic acid X5:Citric acid	98.92	=−0.483–0.103 ×1 + 0.6660 X2 – 0.4301 ×3 + 0.485 X4 – 0.068 ×5 + 0.0287 X1*X4 + 0.02734 X2*X3 – 0.08320 X2*X4 – 0.02304 X2*X5 + 0.0479 X4*X5
Sn	X1:Oxalic acid X2:Malonic acid X3:Maleic acid X4:Malic acid X5:Citric acid	94.70	= 0.0083–0.00895 ×1 + 0.00912 X2 + 0.00667 X3 + 0.02020 X4- 0.00363 X5- 0.000985 X1*X2 + 0.001888 X1*X5 + 0.001120 X2*X3- 0.002018 X3*X5- 0.001089 X4*X5
Se	X1:Oxalic acid X2:Malonic acid X3:Succinic acid X4:Malic acid X5:Citric acid	95.36	= 1.650–0.1355 ×1 + 0.2883 X2- 0.1325 X3- 0.2532 ×4 + 0.1356 X5 + 0.02209 X1^2- 0.01859 X1*X4- 0.01991 X1*X5- 0.01724 X2*X4- 0.00890 X2*X5 + 0.01808 X3*X4 + 0.02928 X4*X5