The present study is targeted toward understanding the interaction between important and technologically relevant polymorphs of iron oxides/oxyhydroxides with arsenic species at neutral pH. The existence of various arsenic (As) species in solution was verified by Raman measurements. Their species-dependent adsorption on the affordable arsenic removal media, confined metastable 2-line ferrihydrite (CM2LF) was investigated. The results were compared with common adsorption media, hematite (α-Fe2O3) and magnetite (Fe3O4). X-ray photoelectron spectroscopy was used to investigate the changes in the core levels of Fe 2p and As 3d resulting from the uptake of arsenic species. Binding of various As species with CM2LF was confirmed by FTIR studies. Raman adsorption data were found to fit a pseudo-second-order model. Results of this study show the synthesized nanocomposite of CM2LF to be very effective for the removal of As(III) and As(V) species in comparison to various materials at neutral pH. A model for the adsorption of As(III) and As(V) species in water on a ferrihydrite particle was developed. This accounted for the large uptake capacity. Copyright © 2018 American Chemical Society.

Pradeep Thalappil

Department Of Chemistry

Chennu Sudhakar

Avula Anil Kumar

Radha Gobinda Bhuin

Soujit Sen Gupta

Ganapati Natarajan

Fourier transform infrared spectroscopy

Hematite

magnetite

Pollution control

X ray photoelectron spectroscopy

ADSORPTION DATA

adsorption mechanism

Arsenic removal

ARSENIC SPECIES

PSEUDO-SECOND ORDER MODEL

Raman measurements

SPECIES SPECIFICS

UPTAKE CAPACITY

Adsorption

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IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

ACS Sustainable Chemistry and Engineering

Fulltext

Sustainable Nanoscale Engineering: From Materials Design to Chemical Processing

Challenges and directions for green chemical engineering-role of nanoscale materials

As(III) and As(V) as well as mixed forms of the same could be effectively scavenged by a composite with fast kinetics allowing the creation of an affordable arsenic-free drinking water solution for point-of-use applications. The granular composites, composed of iron oxyhydroxide-chitosan nanostructures, were synthesized by a green synthetic route, which in general involves the hydrolysis of a metal precursor-chitosan complex using an alkaline medium followed by washing and drying at ambient conditions. Metal ion precursor used for the preparation of the composite was Fe3+. All syntheses were carried out in deionized water, while natural ground water or tap water was used for testing. An iron oxyhydroxide-chitosan nanostructure was synthesized. 25 mg of confined metastable 2-line ferrihydrite (CM2LF) was shaken with 100 mL of natural tap water. Arsenic removal efficiency of CM2LF was measured by spiking the natural tap water with As(III) and As(V) separately. Thereafter, the water was left standing for 1.5 h and subsequently the leftover arsenic concentration in treated water was analyzed using inductively coupled plasma mass spectrometry (ICP-MS) after acidification with 5% HNO3. Experiments with water filtration cartridges are described in the main Text. The unprecedented large capacity in field conditions is attributed to the inherent structure of the composite with confined metastable 2-line ferrihydrite in biopolymer cages, which allows the creation of effective adsorption sites. The arsenic adsorption capacity of the composite is 1.4 to 7.6 times better than the available compositions.

Advanced Materials

Confined Metastable 2-Line Ferrihydrite for Affordable Point-of-Use Arsenic-Free Drinking Water

The Journal of Physical Chemistry C

Kinetic and Mechanistic Evaluation of Inorganic Arsenic Species Adsorption onto Humic Acid Grafted Magnetite Nanoparticles

Chemosphere

A novel biodegradable arsenic adsorbent by immobilization of iron oxyhydroxide (FeOOH) on the root powder of long-root Eichhornia crassipes

Current Opinion in Green and Sustainable Chemistry

Last advances on TiO 2 -photocatalytic removal of chromium, uranium and arsenic

Effective aqueous arsenic removal using zero valent iron doped MWCNT synthesized by in situ CVD method using natural α-Fe2O3 as a precursor

Species-Specific Uptake of Arsenic on Confined Metastable 2-Line Ferrihydrite: A Combined Raman-X-Ray Photoelectron Spectroscopy Investigation of the Adsorption Mechanism

Journal	Data powered by TypesetACS Sustainable Chemistry and Engineering
Publisher	Data powered by TypesetAmerican Chemical Society
ISSN	21680485
Open Access	No