Removal Of Arsenic Contaminants Research Articles

Removal of As(V) from aqueous solution using modified Fe3O4 nanoparticles.

The removal of arsenic contamination from the aqueous environment is of great importance in the conservation of the Earth's water resources, and surfactants are a promising material used to modify magnetic nanoparticles to improve adsorption properties. Therefore, it is important to develop efficient and selective adsorbents for arsenic. Surface modification of Fe3O4 was carried out using anionic, cationic and zwitterionic surfactants to obtain composite Fe3O4@SDS, Fe3O4@CTAB, Fe3O4@SNC 16 and Fe3O4@NPC 16 (collectively referred to as Fe3O4@surfactants). The synthesized composite Fe3O4@surfactants magnetic nanoparticles were characterized by XRD, TEM and FTIR. The As(V) removal characteristics of the composite magnetic nanoparticles from the aqueous solution were evaluated by adsorption batch experiments which indicated the possibility of effective application of the surfactant-modified Fe3O4 magnetic nanoparticles for the removal of As(V) from aqueous solution. The adsorption equilibrium of the composites was reached in 30 min and the kinetic data followed the pseudo-second-order model. Langmuir equation could represent the adsorption isotherm data very well. Moreover, under the identical conditions, Fe3O4@CTAB showed maximum capacity of adsorption for As(V) (55.671 mg g-1), with its removal efficiency being much higher than that of the other composites. In addition, the Fe3O4@surfactants composite magnetic nanoparticles retained 93.5% of its initial arsenic removal efficiency even after re-using it five times. The mechanism of arsenic adsorption by Fe3O4@surfactants composite magnetic nanoparticles was proved to be complexation via electrostatic attraction, which was mainly innersphere in nature.

Detection and removal of arsenic contamination from aqueous media using nanomaterials

Compounds containing Arsenic (As) have been contaminating the ground water not only in India, but also in other countries of the world. Millions of people are affected by various Arsenic-related diseases, such as skin diseases, cardiovascular diseases, neurological disorders, etc. Due to these reasons, extensive research is being carried for detection and removal of arsenic-containing compounds by various research groups. Numerous arsenic moieties, such as As(III) containing H3AsO3, H2AsO3−, HAsO32−; As(V) containing H3AsO4, H2AsO4−, HAsO42− as well as organoarsenic compounds are being actively studied in order to detect these from different aqueous sources. Several research groups are also investigating methods for removal of these ions and compounds using nanomaterials. Herein, we briefly recount the recent and diverse research activities, carried out by various researchers, in this important area in the past few years.

Sustainable removal of arsenate, arsenite and bacterial contamination from water using biochar stabilized iron and copper oxide nanoparticles and associated mechanism of the remediation process

Iron and copper oxide nanoparticles have proven the capability of arsenic remediation, but their use in community-level water purification processes becomes limited due to their irreversible aggregation property. This behavior decreases the active surface area and lowers its effectiveness in the removal of arsenic contamination. In the present study, novel rice-husk biochar stabilized iron and copper oxide nanoparticles (biochar@Fe and biochar@Cu) were developed for efficient removal of total arsenic (arsenite + arsenate, AsIII+V) and microbial contaminants from water. The composites were synthesized by treating microporous rice-husk char with FeCl3 and CuCl2 and their subsequent reaction with NaOH and drying at 90 °C. The mixture of composites, i.e. biochar@Fe and biochar@Cu showed high arsenic removal efficiency, > 95 %, which is dependent on the contact time, pH, and the co-existing anions. The efficiency was examined with a real groundwater sample which showed 92 % removal. The analysis of arsenic speciation after adsorption revealed that the removal process occurs with the oxidation of most of the AsIII to AsV in the presence of CuO, followed by the adsorption of AsV and residual AsIII by Fe2O3 and CuO nanoparticles. The adsorption process followed the pseudo-second-order kinetic model and Freundlich adsorption isotherm with a maximum capacity of 20.32 mg/g. Based on these results, a mechanism of arsenic adsorption was established where it is proposed that arsenic is adsorbed by electrostatic and covalent type interactions between Fe/Cu–OH/OH2+ groups of the composites and AsIII/V–OH/AsVO– of arsenic species. These multiple interactions make the combined biochar@Fe and biochar@Cu system efficient and robust for arsenic filtration compared to any other reported platform.

Removal of arsenic contaminants using a novel porous nanoadsorbent with superior magnetic recovery

Novel porous and magnetic iron oxide nanoparticles (PMNPs) with good magnetic properties were synthesized through a simple sol–gel method and exhibited excellent adsorption performance for aqueous arsenic contaminants as well as magnetic recoverability. Hysteresis loop analysis confirmed that the PMNPs were typical superparamagnetic material with a ultrahigh magnetic saturation (Ms) of 94.77 emu/g, which allowed their quick and complete recovery even under magnetic fields less than 0.25 T. The kinetics and isotherms results confirmed that adsorption equilibrium could achieved in 30 min and the saturated adsorption capacities for As(III) and As(V) exceeded 0.64 and 0.76 mmol/g at 30 °C. The effects of initial pH and diverse co-existing ions demonstrated that the optimal conditions for arsenic removal were closely related to the PMNPs surface charge distribution and the electron density of As(III) and As(V). In addition, after 10 adsorption–desorption cycles, PMNPs still held more than 80% of the primal arsenic adsorption capacities.

Removal of Arsenic Contamination from Gomti River Water by using Activated Charcoal Absorbent Integrated with Solar Distillation Unit

Arsenic is a ubiquitous and short-term poisoning element, which affects living things. In this study, the removal of arsenic from Gomti river water, Lucknow, Uttar Pradesh integrated modified double slope solar still with activated adsorption bed has been applied. Arsenic contamination in Gomti river at five places were found in the river water in the range of 55.70 ppb to 681.60 ppb, which exceed the maximum permissible limit of 10 ppb as recommended by WHO. Maximum concentration of arsenic in water was found in Mohan Maekins (681.60 ppb). However, mean arsenic concentration in water followed the order: Gaughat (115.37 ppb) < Hanuman setu (297.80 ppb) < Barrage (302.62 ppb) <Kukrail (336.27 ppb) < Mohan Maekins (481.89 ppb). The amount of adsorbed arsenic was increased with increasing initial concentration of arsenic. The aim of this study is to develop a low-cost process for the removal of arsenic effectively including the production of potable water. After results, data were analyzed with ICP-MS method and also verified with Langmuir and Freundlich adsorption isotherm models.