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Background & Objective: Nowadays, since increasing environmental pollution particularly soil contamination can cause adverse health effects, kind of methods such as phytoremediation techniques are commonly used to remediate organic, inorganic and nuclear pollutants from contaminated sites. Therefore, this study was conducted to assess of chelating agents with different biodegradability rates on the enhanced phytoremediation efficiency of Amaranthus caudatus and Tagetes patula as ornamental species in cadmium contaminated soils in 2018. Materials & Methods: In pot experiments, the soil specimens were moderately artificially contaminated by cadmium chloride (50 and 100 mg/kg). Then 2.5 mmol/kg of EDTA, 2.0 mmol/kg of salicylic acid (SA) and 2.5 mmol/kg of citric acid (CA) solution were added to the contaminated soils to study the influence of these chelating agents on phytoremediation efficiency by studied ornamental plants. Finally, after acid digestion of cultivated soil, roots and stems of A. caudatus and T. patula, the Cd content was determined using ICP-OES. Results: The results showed that after 60 days of pots irrigation, the maximum mean content of Cd (mg/kg) in cultivated soil, root and stem samples of A. caudatus with 1.87, 4.50 and 1.89 were found in the SA, EDTA and SA treatments, respectively. Moreover, the maximum mean content of Cd in cultivated soil, root and stem samples of T. patula with 1.86, 1.18 and 3.10 were found in the control, CA and SA treatments, respectively. Also, the values of translocation and bioconcentration factors indicate that A. patula can be considered to be potential plant species for phytostabilization and phytoextraction of cadmium, respectively. Conclusion: The results reported in this study show that the organic acids such as SA and CA have considerable role in soil refining electrokinetic or enhance of soil electrokinetic bioremediation through mechanisms resembling hormonelike effects, phosphate release and dissolution, enhancing of cadmium mobility and some enzymatic activities, microstructural variations and retention capacity decreasing of clay particles. Therefore, due to the desirable effects of organic acids as chelate agents to enhancing phytoremediation efficiency of hyperaccumulator species use of these compounds in the cleanup of contaminated soil is recommended.

Introduction: Excess fluoride ions in drinking water cause several diseases so the defluoridation of drinking water for removing the excess fluoride is necessary for human health. Hence this work describes fluoride removal from water using MgFe2O4- chitosan nanocomposite. Methods: In this work, a nitrate salt of Mg and Fe was used to synthesis MgFe2O4 through a combustion route. Then MgFe2O4 - chitosan nanocomposite was synthesized using epichlorohydrin as a linker. Characterization of the sorbent was performed with FESEM, TEM, VSM, EDX, and XRD techniques. Effective parameters on the adsorption process such as pH, contact time, adsorbent dosage, and fluoride concentration were optimized by response surface methodology (RSM) using Box - Behnken design (BBD). Isotherm study was studied at the fluoride concentration range of 10- 100 mg/L. Results: The optimum value of pH, contact time, adsorbent dosage, and fluoride concentration was 2.8, 4.5 min, 19.0 mg, and 28.87 mg/L, respectively. At the optimum condition, the maximum removal efficiency was 98.1%. Results showed that the adsorption process followed the Langmuir model with a capacity of 181.1 mg/g. Conclusion: The result of the present work showed that the nanohybrid has good potential as a cheap magnetic sorbent for environmental remediation purpose as can be used for effective removal of fluoride from water solution. [ABSTRACT FROM AUTHOR]