title: Experimental and modeling analyses for interactions between graphene oxide and quartz sand.
abstract: The aim of this study was to quantify the interactions between graphene oxide (GO) and quartz sand by conducting experimental and modeling analyses. The results show that both GO and quartz sand were negatively charged in the presence of 0-50 mM NaCl and 5 mM CaCl2(GO = -43.10 to -17.60 mV, quartz sand = -40.97 to -8.44 mV). In the Derjaguin-Landau-Verwey-Overbeek (DLVO) energy profiles, the adhesion of GO to quartz sand becomes more favorable with increasing NaCl concentration from 0 to 10 mM because the interaction energy profile was compressed and the primary maximum energy barrier was lowered. At 50 mM NaCl and 5 mM CaCl2, the primary maximum energy barrier even disappeared, resulting in highly favorable conditions for GO retention to quartz sand. In the Maxwell model analysis, the probability of GO adhesion to quartz sand (αm) increased from 2.46 × 10-4to 9.98 × 10-1at ionic strengths of 0-10 mM NaCl. In the column experiments (column length = 10 cm, inner diameter = 2.5 cm, flow rate = 0.5 mL min-1), the mass removal (Mr) of GO in quartz sand increased from 5.4% to 97.8% as the NaCl concentration was increased from 0 to 50 mM, indicating that the mobility of GO was high in low ionic strength solutions and decreased with increasing ionic strength. The Mr value of GO at 5 mM CaCl2was 100%, demonstrating that Ca2+had a much stronger effect than Na+on the mobility of GO. In addition, the mobility of GO was lower than that of chloride (Mr = 1.4%) but far higher than that of multi-walled carbon nanotubes (Mr = 87.0%) in deionized water. In aluminum oxide-coated sand, the Mr value of GO was 98.1% at 0 mM NaCl, revealing that the mobility of GO was reduced in the presence of metal oxides. The transport model analysis indicates that the value of the dimensionless attachment rate coefficient (Da) increased from 0.11 to 4.47 as the NaCl concentration was increased from 0 to 50 mM. In the colloid filtration model analysis, the probability of GO sticking to quartz sand (αf) increased from 6.23 × 10-3to 2.52 × 10-1as the NaCl concentration was increased from 0 to 50 mM.
authors.affiliation: a Environmental Functional Materials and Water Treatment Laboratory , Seoul National University , Seoul , Korea.
authors.forename: Jin-Kyu
authors.initials: JK
authors.lastname: Kang
authors.affiliation: b Center for Water Resource Cycle Research , Korea Institute of Science and Technology , Seoul , Korea.
authors.forename: Jeong-Ann
authors.initials: JA
authors.lastname: Park
authors.affiliation: a Environmental Functional Materials and Water Treatment Laboratory , Seoul National University , Seoul , Korea.
authors.forename: In-Geol
authors.initials: IG
authors.lastname: Yi
authors.affiliation: a Environmental Functional Materials and Water Treatment Laboratory , Seoul National University , Seoul , Korea.|c Department of Rural Systems Engineering and Research Institute of Agriculture and Life Sciences , Seoul National University , Seoul , Korea.
authors.forename: Song-Bae
authors.initials: SB
authors.lastname: Kim
mesh_terms: D006108:Graphite / Q000737:chemistry*; D008962:Models, Theoretical; D010087:Oxides / Q000737:chemistry*; D011791:Quartz / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D010087:Oxides; D014874:Water Pollutants, Chemical; D011791:Quartz; D006108:Graphite
keywords: Colloid filtration theory; DLVO theory; Maxwell model; graphene oxide; transport model