Iron-impregnated granular activated carbon for arsenic removal: Application to practical column filters

Abstract

Highlights Incorporating Fe into granular activated carbon (GAC) increased As(V) adsorption. GAC-Fe's higher As removal is due to more positive charges and specific adsorption. Intra-particle diffusion processes controlled adsorption kinetics  GAC-Fe treated more water than GAC in reducing As levels to WHO guideline level.

Laterite as a low-cost adsorbent in a sustainable decentralized filtration system to remove arsenic from groundwater in Vietnam

“…The existence of arsenic element on the surface of NLTT (Figure S6) after adsorption confirmed that the adsorption of As(III) and As(V) onto NLTT was successful and occurred mainly on the surface of NLTT. Notably, referring to the adsorption of As(V), the surface interaction possibly involved weak electrostatic attraction (outersphere complexation) and surface complexation (inner-sphere complexation) (Kalaruban et al 2019). Meanwhile, the oxidation of arsenite As(III) to arsenate As(V) and the complexation between arsenic ions in solution and the -OH groups on the surface of NLTT might be dominant reactions for the adsorption of As(III) (Cheng et al, 2019;Partey et al, 2009;Pozdnyakov et al, 2016;Zhao et al, 2018).…”

“…In column-based filters they cause hydraulic problems by clogging the filters. Other popular commercial adsorbents (i.e., activated carbon and activated alumina) can also effectively remove arsenic from water (Kalaruban et al, 2019). However, relatively high cost might prevent them from practical applications in villages.…”

Low-cost laterite-laden household filters for removing arsenic from groundwater in Vietnam and waste management

“…When the sand filter treated water was passed through the NLTT filter, most of the remaining As in the form of As(V) in the water was removed by adsorption on the Fe and Al oxides/hydroxides in the laterite by inner-sphere complexation as explained by others (Kalaruban et al, 2019;Mohan and Pittman Jr, 2007;Nguyen et al, 2020a). The reactions are represented by the following equations:…”

“…However, their practical application in column filters is very limited as their fine powder form can lead to clogging of filters. Other popular commercial adsorbents (i.e., activated carbon and activated alumina) have been identified as highly effective for removing toxic As(III) and As(V) (Kalaruban et al, 2019). However, their prices and regeneration costs are relatively high.…”

Removal of organic matter from wastewater reverse osmosis concentrate using granular activated carbon and anion exchange resin adsorbent columns in sequence

“…Furthermore, it possesses negative charges resulting from the ionisation of surface carboxylic and phenolic groups. The zero point of charge (pH at which the net surface charge is zero) of GAC is 3.2, indicating that above this pH the surface charge on GAC is negative (Kalaruban et al, 2019). Both the hydrophobic character and negative charges on GAC are not favourable for the adsorption of humics materials which are mostly negatively charged (Yang et al, 2014).…”