The nanoscale humic acid-urea complexes of 70—90 nm were prepared using nanoscale humic acid and urea as raw materials through complex reaction in order to determine their production process conditions and physical and chemical properties. The optimal process conditions of preparation nanoscale humic acid-urea complexes using response surface methodology was as follows: reaction temperature 47.6℃

reaction time 1.80 h

sodium dodecyl sulfate (as activator) concentration 50.0% (mass)

solid-liquid mole ratio 9:1

concentration of complexing agent 0.14 mol·L-1 and urea dosage 200 mg. Three separate experiments were carried out in the above conditions with product yield of 90.6%±0.9%

which was agreed with the predicted yield of 91.2% by the model. The quadratic polynomial equation model of response and factor was established. The crystal form

component

morphology and specific surface area were characterized respectively by XRD

FTIR

TG

SEM

BET and so on. The results showed that the complex had perfect crystal form

high purity

uniform granularity and good dispersibility with particle size of 70—90 nm

specific surface area 189.85 m2·g-1

mean pore size 10.2 nm and pore volume 0.86 cm3·g-1

and also higher heat stability.