Direct air capture (DAC) and sequestration of CO: Dramatic effect of coordinated Cu(II) onto a chelating weak base ion exchanger.

Direct air capture (DAC) is important for achieving net-zero greenhouse gas emissions by 2050. However, the ultradilute atmospheric CO concentration (~400 parts per million) poses a formidable hurdle for high CO capture capacities using sorption-desorption processes. Here, we present a Lewis acid-base interaction-derived hybrid sorbent with polyamine-Cu(II) complex enabling over 5.

Fluoride removal from groundwater using Zirconium Impregnated Anion Exchange Resin.

Drinking water containing excess fluoride is a major health concern across the globe. The present study reports the feasibility of zirconium impregnated hybrid anion exchange resin (HAIX-Zr) for treating fluoride contaminated groundwater. The HAIX-Zr resin was prepared by impregnating ZrO nanoparticles on polymeric anion exchanger resin.

Evidence of Economically Sustainable Village-Scale Microenterprises for Arsenic Remediation in Developing Countries.

Although unknown 25 years ago, natural arsenic contamination of groundwater affects over 50 countries and up to 200 million people. The economic viability was analyzed and modeled of eighty-eight community-based arsenic mitigation systems existing for up to 20 years in India and Bangladesh. The performances of three community-based arsenic mitigation systems that are ethnically different and separated across two different countries were monitored closely for 24 months of self-sustainable, long-term operation at WHO standards through local, paid caretakers.

Aluminum-Cycle Ion Exchange Process for Hardness Removal: A New Approach for Sustainable Softening.

From a sustainability viewpoint, sodium exchange softening, although used widely, is under scrutiny due to its production of excess Na-laden spent regenerant and subsequent discharge to the environment. Many arid regions are introducing regulations disallowing dumping of concentrated sodium salts, the residuals from popular Na-exchange softening. The sodium content of the softened water is, also, always higher than in the feed, which poses a dietary health concern when used for drinking or cooking.

Integrating tunable anion exchange with reverse osmosis for enhanced recovery during inland brackish water desalination.

For inland brackish water desalination by reverse osmosis or RO, concentrate or reject disposal poses a major challenge. However, enhanced recovery and consequent reduction in the reject volume using RO processes is limited by the solubility of ions present in the feedwater. One of the most common and stubborn precipitate formed during desalination is calcium sulfate.

Investigation on the long-term storage and fate of arsenic obtained as a treatment residual: a case study.

In several places in India, activated alumina is used for effective removal of arsenic from contaminated ground water used for drinking purposes. Once exhausted, activated alumina is regenerated and reused for number of cycles. Regeneration of activated alumina generates treatment residuals containing arsenic, disposal of which needs care so as to avoid further pollution of the neighbouring environment.

Mitigating arsenic crisis in the developing world: role of robust, reusable and selective hybrid anion exchanger (HAIX).

In trying to address the public health crisis from the lack of potable water, millions of tube wells have been installed across the world. From these tube wells, natural groundwater contamination from arsenic regularly puts at risk the health of over 100 million people in South and Southeast Asia. Although there have been many research projects, awards and publications, appropriate treatment technology has not been matched to ground level realities and water solutions have not scaled to reach millions of people.

Hydrogen ion (H+) in waste acid as a driver for environmentally sustainable processes: opportunities and challenges.

Acid-base neutralization reaction in the aqueous phase is thermodynamically favorable and kinetically fast. Waste acid neutralization is also the most common waste management practice globally. However, waste acid neutralization is yet to be used for any work/energy generation because of the low concentrations of the waste acid and the high heat capacity of aqueous solutions.

Sustainable engineered processes to mitigate the global arsenic crisis in drinking water: challenges and progress.

Millions of people around the world are currently living under the threat of developing serious health problems owing to ingestion of dangerous concentrations of arsenic through their drinking water. In many places, treatment of arsenic-contaminated water is an urgent necessity owing to a lack of safe alternative sources. Sustainable production of arsenic-safe water from an arsenic-contaminated raw water source is currently a challenge.

Carminic acid modified anion exchanger for the removal and preconcentration of Mo(VI) from wastewater.

Removal and preconcentration of Mo(VI) from water and wastewater solutions was investigated using carminic acid modified anion exchanger (IRA743). Various factors influencing the adsorption of Mo(VI), e.g.

Evolution of community-based arsenic removal systems in remote villages in West Bengal, India: assessment of decade-long operation.

In Bangladesh and the neighboring state of West Bengal, India, over 100 million people are affected by widespread arsenic poisoning through drinking water drawn from underground sources containing arsenic at concentrations well above the permissible limit of 50 μg/L. The health effects caused by arsenic poisoning in this area is as catastrophic as any other natural calamity that occurred throughout the world in recent times. Since 1997, over 200 community level arsenic removal units have been installed in Indian subcontinent through collaboration between Bengal Engineering and Science University (BESU), India and Lehigh University, USA.

Preparation of Fe oxide nanoparticles for environmental applications: arsenic removal.

The objective of this study is to examine the adsorption-desorption behavior of a magnetically active hybrid sorbent (MAHS) material, prepared by dispersing colloid-like hydrated iron oxide particles in the outer periphery of a macroporous ion-exchange resin (Amberlite XAD-2). The experimental results show that the new sorbent material can simultaneously remove arsenic (V) and a chlorinated organic compound (2,6-dichlorophenol [2,6-DCP]) from aqueous solutions at around neutral pH. The recovery of arsenic and 2,6-DCP from MAHS was conducted using a regenerant containing 50% (v/v) CH3OH + 3% (w/v) NaOH.

The Donnan membrane principle: opportunities for sustainable engineered processes and materials.

The Donnan membrane principle can permit many engineered processes and materials to achieve better sustainability.

Arsenic removal from groundwater and its safe containment in a rural environment: validation of a sustainable approach.

Of all the naturally occurring groundwater contaminants, arsenic is by far the most toxic. Any large-scale treatment strategy to remove arsenic from groundwater must take into consideration safe containment of the arsenic removed with no adverse ecological impact. Currently, 175 well-head community-based arsenic removal units are in operation in remote villages of the Indian subcontinent.

Hybrid anion exchanger for trace phosphate removal from water and wastewater.

Throughout recent decades, the wastewater treatment industry has identified the discharge of nutrients, including phosphates and nitrates, into waterways as a risk to natural environments due to the serious effects of eutrophication. For this reason, new tertiary treatment processes have abounded; these processes generally utilize physico-chemical and biological methods to remove nutrients from secondary wastewaters. The disadvantages of such methods involve larger reactor volumes, operating costs, and waste sludge production; furthermore, complete nutrient removal is unattainable due to thermodynamic and kinetic limitations.

Environmentally benign hardness removal using ion-exchange fibers and snowmelt.

Many industrial unit operations and unit processes require near-complete removal of hardness to avoid scaling in heat-transfer equipment, fouling in membranes, and high consumption of detergents and sequestering chemicals in cooling and wash water. Lime softening and cation exchange are the most commonly used processes practiced to date for hardness removal. Herein, we report and discuss the results and attributes of a new hardness removal process using ion-exchange fibers (IX-fibers).

Arsenic removal using polymer-supported hydrated iron(III) oxide nanoparticles: role of donnan membrane effect.

The conditions leading to the Donnan membrane equilibrium arise from the inability of ions to diffuse out from one phase in a heterogeneous system. In a polymeric cation exchanger, negatively charged sulfonic acid groups are covalently attached to the polymer chains, and thus, they cannot permeate out of the polymer phase. Conversely, a polymeric anion exchanger contains a high concentration of non-diffusible positively charged quaternary ammonium functional groups.

Well-head arsenic removal units in remote villages of Indian subcontinent: field results and performance evaluation.

Since 1997, over 135 well-head arsenic removal units have been installed in remote villages in the Indian state of West Bengal bordering Bangladesh. Every component of the arsenic removal treatment system including activated alumina sorbent is procured indigenously. Each unit serves approximately 200-300 households and contains about 100 L of activated alumina.

Selective coagulant recovery from water treatment plant residuals using Donnan membrane process.

Fouling of membrane surfaces by particulate matter and large organic molecules is relatively common for pressure-driven membrane processes, namely, reverse osmosis (RO), nanofiltration (NF), and ultrafiltration (UF). Donnan membrane process (DMP) or Donnan Dialysis is driven by electrochemical potential gradient across a semipermeable ion exchange membrane. Theoretically, DMP is not susceptible to fouling by fine particulates and/or large organic molecules.

Arsenic removal using a polymeric/inorganic hybrid sorbent.

A fixed-bed sorption process can be very effective in removing trace concentrations of arsenic from contaminated groundwater provided: the sorbent is very selective toward both As(III) and As(V) species; the influent and treated water do not warrant any additional pre- or post- treatment; pH and composition of the raw water with respect to other electrolytes remain unchanged besides arsenic removal, and the sorbent is durable with excellent attrition resistance properties. In addition, the sorbent should be amenable to efficient regeneration for multiple reuse. This study reports the results of an extensive investigation pertaining to arsenic removal properties of a polymeric/inorganic hybrid sorbent.