Investigating the Efficiency of Functionalized PAMAM-GO Nano-Composite for Nitrate Removal from Aqua Solutions

Due to the high solubility of nitrate in water, conventional treatment methods fail to remove it. This research investigated for the first time in national and global level, the efficiency of functionalized PAMAM-Go nanocomposite for nitrate removal from aquatic solutions. GO was synthesized by modified Hummers method. AFM images were used to characterize the GO and the AGO. Experiments were performed in a batch reactor and the main factors of pH, reaction time, and concentration of PAMAM_GO were investigated. The highest removal efficiency was obtained as 84% at 5 mL/L functionalized PAMAM_GO, pH of 3 and 25 min reaction time. The results showed that nitrate removal by functionalized PAMAM-Go nanocomposite is directly correlated with nanocomposite concentration and contact time while it is inversely correlated with pH and initial concentration of nitrate. It seems that ion exchange between nitrate and chloride is the main mechanism of nitrate removal by functionalized PAMAM_GO nano composite according to functionalization of PAMAM-Go using hydrochloric acid. This method can be used as a suitable method for in situ treatment of nitrate and many  pollutants in water and wastewater, due to its easy operation, no need for high levels of expertise and sophisticated equipment, no need for large space of construction, low initial investment, low price, availability of raw materials, simple synthesis of graphene oxide and  easy  to functionalize

Efficiency Evaluation of Nitrate Removal from Synthetic Solutions by Dendrimer- Graphene Oxide Nano-Composite Activated with HCl

High soluability of nitrate ions in water cause the dysfunction of many existing treatment methods in the removal of this very dangerous ion from aqueous media. On the other hand,  due to the need for in situ treatment methods, in particular for groundwater, the replacement of old inefficient methods with new compounds is required. In this study, for the first time, the efficiency of activated dendrimer- graphene oxide for nitrate removal from an aquatic solution was investigated. Experiments were performed in a batch reactor and the main factors of pH, reaction time, and concentration of PAMAM-GO were investigated. The highest removal efficiency was obtained as 90% at 0.025mg/L activated dendrimer- graphene oxide, pH of 7.5 and 15 min reaction time. The results showed that nitrate removal by activated dendrimer-graphene oxide is correlated with nanocomposite concentration, contact time, pH and initial concentration of nitrate. It seems that ion exchange between nitrate and chloride is the main mechanism of nitrate removal by activated dendrimer-graphene oxide according to functionalization of activated dendrimer-graphene oxide using hydrochloric acid. This method can be used as a suitable method for in situ removal of nitrate from water and wastewater due to the desirable ability of the nanocomposite and its optimal compatibility with the environment

Study of Adsorption Equilibrium and Kinetics of direct blue 71 by activated red mud from aqueous solutions

Background: Some of dyes are toxic and even carcinogenic and require separation and advanced treatment of textile effluents before being discharged into conventional systems. The objective of this study was to remove the direct blue 71 dye from aqueous solutions using activated red mud. Methods: Red mud was activated by nitric acid and was used in the adsorption experiment. Direct blue 71 removal, using activated red mud was studied as a function of contact time, pH, and initial dye concentration. The adsorption isotherms were analyzed using the Langmuir and the Freundlich isotherms. Kinetics data were fitted with Pseudo-first-order and Pseudo-second-order models. Results: The adsorption rate increases with pH decrease, contact time increase, and increase initial dye concentrations. The Freundlich isotherm (R2=0.9737) was the best-fit adsorption isotherm model for the experiment. The adsorption data, followed a pseudo-second-order model (R2=0.9902). Conclusion: Based on the result of the study, the use of activated red mud, as an efficient low-cost adsorbent, can be considered for (pre-) treating direct blue 71 contaminated wastewater. Keywords: Direct blue 71, Textile wastewater, Activated red mud, Adsorption, Isotherm model

Evaluating Environmental Health Students\' Attitudes toward their Discipline and Future Career in Hamedan University of Medical Sciences in 2008

Introduction: The raise of medical sciences graduates is counted to be on of the problems in public, as concern about the discipline and future career is evidently seen in students. This study was performed with the aim of determining environmental health students' attitude toward their discipline and future career carried out in Hamedan University of Medical Sciences in 2008. Methods: All environmental health students of Hamedan University of Medical Sciences studying morning courses of first semester of academic year 2008-2009 in associate, BS, and MS degrees were entered into this descriptive cross sectional study through census (n=115). The data gathering tool was Minnesota University questionnaire including 20 questions based on Likert scale. Data was analyzed by SPSS software using statistical t-test. Results: Mean and standard deviation of students' attitude toward their future career attained to be 56.6 and 11.2 respectively out of 96 questionnaires. Regarding the score of 60 as the mean score of the test, the attained mean score is lower than expected. Conclusion: The mean score for attitude of population under investigation toward their future career was lower than acceptable level which demonstrates lack of desirable attitude toward future career among students. It is while they have an acceptable attitude toward their discipline. Adjusting the number of students accepted, proper distribution of human resources, informing students about university disciplines before they take the entrance examination, and supporting the students financially may prove helpful in improving their attitudes

Investigating the Efficiency of Dissolved Air Flotation Process for Aniline Removal from aquatic Environments

Aniline is an almost undegradable compound found in many industrial effluents. It was the objective of this lab-scale applied-experimental study to determine the efficiency of the dissolved air flotation process in the removal of aniline from aquatic environments. Initially, the optimal conditions of pH and dosage of poly-aluminum chloride were determined using the jar test. The parameters involved in the dissolved air flotation process including coagulant concentration (10, 20, 30, 40, and 60 mg.l‒1), coagulation time (5, 10 , 15, and 20 min), flotation time (5, 10, 15, and 20 s), saturation pressure (3.5 / 3, 4, and 5.4 atmospheres), and turbidity (10, 20, 30, 40, and 60 NTU) on the reduction of COD and aniline were then calculated. Results showed that the dissolved air flotation process was capable of reducing COD and aniline by 86.6% and 95%, respectively (at pH = 6, an initial aniline concentration of 200 mg/ L, a coagulation time of 10 min, a flotation time of 20 s, a saturation pressure of 4 atmospheres, and a concentration of 20 mg/L PAC). It was also shown that removal efficiency declines with increasing turbidity. It may, therefore, be claimed that the dissolved air flotation process is an effective method of removing aniline from aquatic environments