Arsenic is considered as one of the most hazardous elements for the living organisms and its presence in natural waters, can result in serious environmental problems. In this study, Moringa peregrina seed extract ability in a batch system to remove arsenate from aqueous solutions was investigated. The effects of major operating variables such as coagulant dose (0.1-5 mL L -1 ) and pH (2-11) were investigated. The optimum pH for removal of arsenic by coagulation using Moringa peregrina seed extract was 6 and the highest removal was found to be 98.61, 99.032 and 98.976 % at initial arsenic(V) concentration 100, 200 and 500 µg L -1 respectively, as a result of precipitation, co-precipitation and adsorption mechanisms. According to achieved results, it was defined that Moringa peregrina seed extract not only was an inexpensive coagulant, but also a quite effective factor in removal of arsenic(V) from aqueous environments.

Background: 2, 4-Dichlorophenoxyacetic acid (2, 4-D) is a widely used herbicide known to be moderately toxic. Extensive use and poor biodegradability of 2, 4-D has resulted in its ubiquitous presence in the environment, and has led to contamination of surface and ground waters. Objectives: At present study, single-walled carbon nanotubes (SWCNTs) were used for the sorption of 2, 4-D from aqueous solutions. Materials and Methods:The effect of various operating parameters such as initial concentration of 2, 4-D, contact time, adsorbent dosage, and pH were investigated. Equilibrium isotherms were used to identify the possible mechanism of the adsorption process. Results: Maximum adsorption capacity of the SWCNTs was 979.6 mg/g at pH5, contact time 45 min, initial concentration of 5000 µg/L, and 23 ± 2 •C temperatures, when 97.96% of 2, 4-D herbicide were removed. The adsorption equilibriums were analyzed by Langmuir and Freundlich isotherm models. It was found that the data fitted to Langmuir (R2 = 0.9987) better than Freundlich (R2 = 0.9727) model. Conclusions: According to achieved results, it was defined that SWCNTs is a quite effective adsorbent in removal of 2, 4-D from aqueous environments.

Background and purpose: Phenol is one of prevalent contaminants found in many industrial wastewaters. The combination with special features, such as high toxicity, carcinogenic properties, vitality gathering ability, low biodegradation potentiality and others, based on the U.S Environmental Protection Agency, classified as a priority pollutant. The purpose of this study was to determine the efficiency of Moringa Peregrina tree shell ash for the removal of phenol from aqueous solutions. Materials and Methods:This study is experimental and pilot scale. To determine the efficiency of Moringa Peregrina tree shell ash for the removal of phenol from aqueous solutions; the examination was carried out in a batch system. To achieve the aim of this study, the effect of each of the parameters affecting the adsorption process, such as initial pH of solution, contact time, adsorbent dose and initial concentration of phenol in solution were studied.Results: The results showed that the highest percentage of phenol removal by the ash occurred at pH 6, initial concentration100 mg.L -1 and adsorbent dose 0.4 g/l in which the 79.96% phenol was removed. For the analysis of the absorption constant, the Freundlich and Langmuir isotherm were used. The results showed that the experimental data fit the Langmuir (R 2 =0.9833) much better than the Freundlich model (R 2 =0.9373). Conclusion:According to the results of this study, it was found that the Moringa Peregrina tree shell ash is not only a low-cost adsorbent but also has a high performance in the removal of phenol from aqueous solutions.

Background: 2, 4-Dichlorophenoxyacetic acid (2, 4-D) is a widely used herbicide known to be moderately toxic. Extensive use and poor biodegradability of 2, 4-D has resulted in its ubiquitous presence in the environment, and has led to contamination of surface and ground waters. Objectives: At present study, single-walled carbon nanotubes (SWCNTs) were used for the sorption of 2, 4-D from aqueous solutions. Materials and Methods: The effect of various operating parameters such as initial concentration of 2, 4-D, contact time, adsorbent dosage, and pH were investigated. Equilibrium isotherms were used to identify the possible mechanism of the adsorption process. Results: Maximum adsorption capacity of the SWCNTs was 979.6 mg/g at pH5, contact time 45 min, initial concentration of 5000 µg/L, and 23 ± 2 •C temperatures, when 97.96% of 2, 4-D herbicide were removed. The adsorption equilibriums were analyzed by Langmuir and Freundlich isotherm models. It was found that the data fitted to Langmuir (R2 = 0.9987) better than Freundlich (R2 = 0.9727) model. Conclusions: According to achieved results, it was defined that SWCNTs is a quite effective adsorbent in removal of 2, 4-D from aqueous environments.