The double influence mechanism of pH on arsenic removal by nano zero valent iron: electrostatic interactions and the corrosion of Fe⁰

Abstract

The pH has a significant impact on arsenic (As) removal by nano zero valent iron (nZVI).

Nanoencapsulation of arsenate with nanoscale zero-valent iron (nZVI): A 3D perspective

“…Removal of As(V) and As(III) by nZVI has been widely documented [28][29][30][31][32][33][34][35][36][37][38][39]. Therefore, confirming the solution chemistry or removal efficiency of nZVI for As(V) separation is not an objective of this work.…”

“…Arsenic pollution is a global problem, and its cost-effective and reliable removal is frequently a challenge for environmental scientists and engineers [16,17]. nZVI is an effective nano-agent for As(V) and As(III) sequestration [16,17,[30][31][32][33][34][35][36][37][38][39]. Although changes in the arsenic valence state have been observed during nZVI treatment, arsenic speciation and underlying mechanisms are not clearly understood.…”

A critical review on arsenic removal from water using iron-based adsorbents

“…The maximum adsorption capacity for As(III) and As(V) at pH 6.5 calculated from Langmuir model was 18.2 and 12.0 mg g À1 , respectively. 109 Wu et al 110 investigated the double inuence mechanism of pH on arsenic removal by nZVI (with an average particle size varying from 30 to 50 nm). The results indicated that an increasing pH decreased the g-FeOOH and increased the Fe 3 O 4 /g-Fe 2 O 3 content in the corrosion products of nZVI, thus enhancing the adsorption affinity of nZVI to As(V).…”

Effects of in situ Remediation With Nanoscale Zero Valence Iron on the Physicochemical Conditions and Bacterial Communities of Groundwater Contaminated With Arsenic

“…An increase in groundwater pH ( Figure 3A ) has been reported to affect transport, mobility and adsorption of contaminants ( Zhang and Elliott, 2006 ), including impairment of the removal of both species of arsenic due to electrostatic repulsion ( Park et al, 2009 ). However, a significant effect of the nanoparticles on the adsorption of As(V) in the groundwater of Nitrastur is unlikely since the highest pH value reached was well below the values that induce a marked decrease of nZVI surface potential and would therefore greatly hinder the adsorption of this form of arsenic ( Park et al, 2009 ; Wu C. et al, 2017 ). On the other hand, an increase in the pH of groundwater alters the proportion of corrosion products of nZVI, such as maghemite, which has a higher adsorption affinity toward As(V) ( Wu C. et al, 2017 ).…”