Treatment of Arsenic Contaminated Groundwater Using Calcium Impregnated Granular Activated Carbon in a Batch Reactor: Optimization of Process Parameters

Abstract

This paper is an experimental investigation into the removal of arsenic species from simulated groundwater by adsorption onto Ca 2+ impregnated granular activated carbon (GAC-Ca) in the presence of impurities like Fe and Mn. The effects of adsorbent concentration, pH and temperature on the percentage removal of total arsenic (As(T)), As(III) and As(V) have been discussed. Under the experimental conditions, the optimum adsorbent concentration of GAC-Ca was found to be 8 g/L with an agitation time of 24 h, which reduced As(T) concentration from 188 to 10 lg/L. Maximum removal of As(V) and As(III) was observed in a pH range of 7 -11 and 9 -11, respectively. Removal of all the above arsenic species decreased slightly with increasing temperature. The presence of Fe and Mn increased the adsorption of arsenic species. Under the experimental conditions at 308C, the maximum percentage removals of As(T), As(III), As(V), Fe, and Mn were found to be ca. 94.3, 90.6, 98.0, 100 and 63%, respectively. It was also observed that amongst the various regenerating liquids used, a 5 N H 2 SO 4 solution exhibited maximum regeneration (ca. 91%) of the spent GAC-Ca.

Effect of pH and Treatment Time on the Removal of Arsenic Species from Simulated Groundwater by Using Fe<SUP>3+</SUP> and Ca<SUP>2+</SUP> Impregnated Granular Activated Charcoals

“…Each 50ml of the synthetic water sample containing 188µg/l As (As(III) : As(V) = 1:1), 2.8mg/l Fe and 0.6mg/l Mn was added with calculated amount of adsorbents, as optimized elsewhere [7,8] in 100ml plastic bottle. The optimum adsorbent dose was fixed to get the arsenic concentration below10µg/l from an initial concentration of 188µg/l.…”

“…However due to impregnation of metal ions the positive charge density on surface modified GACs increases as consequently arsenic removal increases. Optimum adsorbent concentrations was considered for GAC, GAC-Fe and GAC-Ca as 16g/l, 5g/l and 8g/l respectively on the basis of earlier experiments as reported elsewhere [7,8]. Thus, the amount of GAC, GAC-Fe and GAC-Ca present in 50ml solution are 0.8g, 0.25g and 0.4g respectively.…”

“…Consequently, the surface of the GAC-Fe is predominantly neutral and hence adsorption takes place predominantly through exchange of hydroxyl ions in this pH range. The detail discussion on the creation of various surface charges on the surface modified GACs and likely route for the adsorption of arsenic species have been provided elsewhere [8].…”

Kinetic, mechanistic and thermodynamic studies of removal of arsenic using Bacillus arsenicus MTCC 4380 immobilized on surface of granular activated carbon/MnFe2O4 composite

“…Loading of MnFe 2 O 4 increased the positive charge density on the adsorbent surface by neutralizing negative surface charge and creating positive charge in its place (Mondal et al, 2009). Mondal et al (2007aMondal et al ( , 2010 reported that impregnation of Ca on the surface of GAC also increased the positive charge on the surface of GAC and finally improved the adsorption capacity of GAC. By comparing the arsenic adsorption capacity of MnFe 2 O 4 with and without the template in Table 5, it was observed the adsorption capacities of MnFe 2 O 4 loading on the acid treated GAC are much higher than the bare ones.…”

Biosorptive Performance of Bacillus arsenicus MTCC 4380 Biofilm Supported on Sawdust/MnFe2O4 Composite for the Removal of As(III) and As(V)

“…Loading of MnFe 2 O 4 increased the positive charge density on the biosorbent surface by neutralizing negative surface charge and creating positive charge in its place [24]. Mondal et al reported that impregnation of Ca on the surface of GAC also increased the positive charge on the surface of GAC and finally improved the adsorption capacity of GAC [25,26]. By comparing the arsenic adsorption capacity of MnFe 2 O 4 with and without the template in Table 4, it was observed that the adsorption capacities of MnFe 2 O 4 loading on the acid-treated sawdust are much higher than the bare ones.…”