Evaluation of a Novel Water Treatment Residual Nanoparticles as a Sorbent for Arsenic Removal

Abstract

A novel sorbent, water treatment residual nanoparticles (nWTR), was synthesized and used to remove As(V) from water solutions. The kinetics and equilibrium of As(V) adsorption by nWTR were evaluated. The kinetic data for nWTR at 3 different pH values indicate that As(V) sorption is biphasic, is favored at low pH values, and followed the power function and first-order kinetics models fit. The results of the batch adsorption study showed that nWTR was effective in As(V) removal and its removal capability was 16 times higher than that of bulk WTR. Fourier transmission infrared (FTIR), SEM-EDX spectra, and As fractionation results indicate the crucial role of surface hydroxyl groups in As retention onto nWTR and the high capability of nWTR to immobilize As(V). The stability of As-nWTR surface complexes is suggested as less than 2% of adsorbed As(V) was released from nWTR after 4 consecutive desorption cycles.

Sorption, Release and Forms of Mercury in Contaminated Soils Stabilized with Water Treatment Residual Nanoparticles

“…Our research findings suggested that application of nWTR could be considered as best management practice to retain and immobilize excess Hg and could provide long-term sorption stability. This is in accordance with the results of Elkhatib et al (2015c), who reported the high capability of nWTR to immobilize As.…”

“…This is in accordance with the results of Elkhatib et al . (), who reported the high capability of nWTR to immobilize As.…”

“…Application of bulk WTR at a rate of 2% decreased NORS‐Hg fraction in non‐amended soils from 44·5 to 21·8 and from 22·8 to 12·5 in clay and sandy soils, respectively (Figure ). These results are in line with previous studies (Moharem et al ., ; Elkhatib et al ., , , ) that document the contribution of WTRs in converting Cu, Pb and Ni fractions from labile forms to more stable forms.…”

“…The sequential extraction (Tessier et al, 1979), a widely used method for metal fractionation, can provide useful information related to mobility and bioavailability of Hg in soils (Elkhatib et al, 2015a(Elkhatib et al, , 2015b(Elkhatib et al, , 2015c. Thus, the effects of WTR/nWTR on geochemical distribution of Hg in fractions of Hg contaminated soils were studied, and the results are presented in Figure 5.…”

“…Water treatment residuals (WTR), waste material resulting from the treatment of surface water with Al and Fe salts, have shown strong affinity for Ni, Cu, Pb and Hg and have been used recently to chemically stabilize contaminated soil (Sarkar et al, 2007;Hovsepyan & Bonzongo, 2009;Elkhatib et al, 2013;Elkhatib et al, 2015aElkhatib et al, , 2015bElkhatib et al, , 2015c. Moreover, conclusive prior studies have demonstrated that the smaller fraction of WTR greatly influences its active surface area and leads to increase its adsorption capacity (Caporale et al, 2013).…”