Removal of heavy metal ions from wastewaters: A review

Arsenic removal from water/wastewater using adsorbents—A critical review

Heavy metals like arsenic, copper, cadmium, chromium, nickel, zinc, lead, and mercury are major pollutants of fresh water reservoirs because of their toxic, non-biodegradable, and persistent nature. The industrial growth is the major source of heavy metals introducing such pollutants into different segments of the environment including air, water, soil, and biosphere. Heavy metals are easily absorbed by fishes and vegetables due to their high solubility in the aquatic environments. Hence, they may accumulate in the human body by means of the food chain. Various methods have been developed and used for water and wastewater treatment to decrease heavy metal concentrations. These technologies include membrane filtration, ion-exchange, adsorption, chemical precipitation, nanotechnology treatments, electrochemical and advanced oxidation processes. In this review, the methods as well as their mechanisms and efficiency are discussed.

Removal of Heavy Metals from Industrial Wastewaters: A Review

In this work, results of {\it ab-initio} band structure calculations for $A_2BC$ Heusler compounds that have $A$ and $B$ sites occupied by transition metals and $C$ by a main group element are presented. This class of materials includes some interesting half-metallic and ferromagnetic properties. The calculations have been performed in order to understand the properties of the minority band gap and the peculiar magnetic behavior found in these materials. Among the interesting aspects of the electronic structure of the materials are the contributions from both $A$ and $B$ atoms to states near the Fermi energy and to the total magnetic moment. The magnitude of the total magnetic moment, which depends as well on the kind of $C$ atoms, shows a trend consistent with the Slater-Pauling type behavior in several classes of these compounds. The localized moment in these magnetic compounds resides at the $B$ site. Other than in the classical Cu$_2$-based Heusler compounds, the $A$ atoms in Co$_2$, Fe$_2$, and Mn$_2$ based compounds may contribute pronounced to the total magnetic moment.

Calculated electronic and magnetic properties of the half-metallic, transition metal based Heusler compounds

In this paper, results of ab initio band structure calculations for A2BC Heusler compounds that have A and B sites occupied by transition metals and C by a main group element are presented. This class of materials includes some interesting half-metallic and ferromagnetic properties. The calculations have been performed in order to understand the properties of the minority band gap, the peculiar transport properties and magnetic behaviour found in these materials. Among the interesting aspects of the electronic structure of the materials are the contributions from both A and B atoms to the total magnetic moment. The magnitude of the total magnetic moment shows a trend consistent with the Slater–Pauling type behaviour in several classes of these compounds. The total magnetic moment also depends on the kind of C atoms although they do not directly contribute to it. In Co2 compounds, a change of the C element changes the contribution of the t2g states to the moment at the Co sites. The localized moment in these magnetic compounds resides at the B site. Other than in the classical Cu2-based Heusler compounds, the A atoms in Co2, Fe2 and Mn2-based compounds may contribute significantly to the total magnetic moment. It is shown that the inclusion of electron–electron correlation in the form of LDA + U calculations helps to understand the magnetic properties of those compounds that already exhibit a minority gap in calculations where it is neglected. Besides the large group of Co2 compounds, half-metallic ferromagnetism was here found only in such compounds that contain Mn.

https://iopscience.iop.org/article/10.1088/0022-3727/40/6/S01/pdf

Arsenic removal by electrocoagulation using combined Al-Fe electrode system and characterization of products

Arsenic removal via electrocoagulation from heavy metal contaminated groundwater in La Comarca Lagunera México

In order to assess the magnetic ordering process in ${\mathrm{Fe}}_{2}\mathrm{VAl}$ and the related material ${\mathrm{Fe}}_{2}\mathrm{VGa},$ we have carried out nuclear magnetic resonance (NMR) and M\"ossbauer studies. ${}^{27}\mathrm{Al}$ NMR relaxation measurements covered the temperature range 4--500 K in ${\mathrm{Fe}}_{2+x}{\mathrm{V}}_{1\ensuremath{-}x}\mathrm{Al}$ samples. We found a peak in the NMR spin-lattice relaxation rate, ${}^{27}{(T}_{1}^{\ensuremath{-}1}),$ corresponding to the magnetic transitions in each of these samples. These peaks appear at 125 K, 17 K, and 165 K for $x=0.10,$ 0, and -0.05, respectively, and we connect these features with critical slowing down of the localized antisite defects. M\"ossbauer measurements for ${\mathrm{Fe}}_{2}\mathrm{VAl}$ and ${\mathrm{Fe}}_{2}\mathrm{VGa}$ showed lines with no hyperfine splitting, and isomer shifts nearly identical to those of the corresponding sites in ${\mathrm{Fe}}_{3}\mathrm{Al}$ and ${\mathrm{Fe}}_{3}\mathrm{Ga},$ respectively. We show that a model in which local band filling leads to magnetic regions in the samples, in addition to the localized antisite defects, can account for the observed magnetic ordering behavior.

/pdf/nmr-and-mossbauer-study-of-spin-dynamics-and-electronic-4lttospt8z.pdf

George Irwin

Papers

Arsenic removal by electrocoagulation using combined Al-Fe electrode system and characterization of products

Arsenic removal via electrocoagulation from heavy metal contaminated groundwater in La Comarca Lagunera México

NMR and Mössbauer study of spin dynamics and electronic structure of Fe2+xV1-xAl and Fe2VGa

Utilization of Electrochemical Techniques for Copper Removal, Speciation, and Analysis in Aqueous Systems

Electrochemical Synthesis of Green Rust and Its Modified Form Developed for Wastewater Treatment in Remote Areas