Application of heated date seeds as a novel extractant for diuron from water

Diuron has a high leachability with GUS value of 4.1 and a very long residence time in the soil. A novel use of date seeds for diuron adsorption and preconcentration from water is reported. Upon heating at 400 °C, the date seeds exhibited a good adsorption and preconcentration of diuron from water, the adsorption capacity is 2.0 mg/g at 25 °C and pH 7. Using principal component analysis PCA, the adsorption of diuron is correlated to the experimental factors as:Kd(distribution value)=0.01(Mass)−0.11(pH)+0.61(Conc.)+0.24(Agt Time)+0.49(Temp.)Kd(distribution value)=0.01(Mass)−0.11(pH)+0.61(Conc.)+0.24(Agt Time)+0.49(Temp.)The preconcentration recovery of diuron is also correlated to the experimental factors as: %Recovery=0.09(Samp. vol.)+1.76(Mass)−4.23(pH)+8.06(Eluent vol.)%Recovery=0.09(Samp. vol.)+1.76(Mass)−4.23(pH)+8.06(Eluent vol.)The PCA revealed that initial concentration and temperature are the most significant factors for diuron adsorption. However, pH and eluent volume are the most significant factors for diuron preconcentration. Diuron adsorption is an endothermic process with ΔH value of 8.0 kJ/mol. The shape of diuron isotherm is “C1” type, which is often reported. More than 75% of adsorbed diuron is desorbed using 0.4 M NaOH solution. Diuron at 100 μg/L level can be accurately analyzed using HDS as a solid-phase extractant.