K Azizi , Ar Mesdaghinia , F Vaezi , S Nasseri ,
Volume 1, Issue 1 (4-2003)
Abstract
Bromide which is present in many water resources has the potential to create adverse health effects after water disinfection by oxidizing agents, and it is considered to be the most important mineral in this respect. Bromide removal is not feasible in conventional water treatment plants. This survey with the aim of removing Br" from water has been accomplished by performing pilot tests in which a GAC fixed - bed contactor and two different resins have been employed. Synthetic water samples of known concentrations of Br" (1-10 mgL -&apos) and TDS (250 - 1000 mg/L-1) have been treated, at the first phase of this study.
Results showed that the best efficiency of GAC treatment was for samples having more than 1 mgL"1 Br" and less than 1000 mgL-1 TDS.
At the second phase of the study, a strong anionic-cathionic resin had been used for Br" removal. Either low or high concentrations of Br", in the influent a considerable reduction in Br" content was always observed at the first 5 minutes of contact.
At the third phase of the study a weak anionic resin (WBA) has been employed. Using this resin in the treatment of synthetic samples proved that WBA is also very effective for Br" removal during 10 min contact while , Br- was reached less than 0.4 mgL"1 . Simultaneous removing of TDS was also showed well efficiency. However, TDS has never decreased to near zero as it was possible for the strong resins.
Finally in the 4th phase of this research, natural samples from four water resources supplying potable water for the city of Qom have been chosen to continue the process of Br" removal by above-mentioned pilots. Despite of high levels of TDS of the samples, there was no important problem in the process of Br" treatment. The acceptable removal efficiencies of bromide were minimum 50% and maximum around 100% .
Bahareh Karimi, Sahar Khanaki, Leyla Ma’mani, Seyed Mostafa Khezri, Asghar Karami,
Volume 15, Issue 4 (3-2018)
Abstract
Background and Aim: Agricultural poisons are one of the most important groups of pollutants in agricultural industries that cause environmental pollution. The main objective of this research was to remove imidacloprid from contaminated water by using modified magnetic-silica core-shell nanoparticles.
Materials and Methods: This study was conducted at the laboratory scale and batch system. The physical and structural characteristics of the synthesized adsorbent were determined by scanning electron microscopy (SEM). In addition, the effects of various parameters such as pH, initial concentration of imidacloprid, adsorbent dose, and contact time were investigated in order to determine the equilibrium isotherms and adsorption kinetics. The potential of the adsorbent for removal of imidacloprid showed no significant change after four runs of the reaction.
Results: The highest efficiency was found to be 97.85 %, achieved at the following conditions: a contact time of 67 minutes, an adsorbent dose of 0.06 g/l, an initial concentration of 15.6 mg/l and a pH of 6.5. The correlation coefficient of Langmuir isotherm (R2=0.9843) was higher than that of Freundlich (R2=0.8). Therefore, the Langmuir isotherm model is hereby introduced to be used for predicting the adsorption behavior of imidacloprid onto the nano-adsorbent from an aqueous medium. The reaction kinetics fitted well with the pseudo-second-order model.
Conclusion: A modified magnetic-silica core-shell nanoparticle is a cost-effective and recoverable adsorbent for efficient removal of imidacloprid from contaminated water.
