Application of eco‐friendly multifunctional porous graphene oxide for adsorptive sequestration of chromium in aqueous solution

Abstract

Graphene oxide (GO) was functionalized using two silanes ((3‐aminopropyl)‐triethoxysilane and (3‐mercaptopropyl)‐triethoxysilane) to obtain, separately, the eco‐friendly amine‐functionalized GO (GONH) and thiol‐functionalized GO (GOSH). Both silanes were also used together to obtain the amine–thiol dual‐functionalized GO (GOSN). Various physicochemical characterizations were obtained including spectra from using Fourier‐transform infrared (FTIR) spectrometer, thermogravimetric analyzer, and X‐ray diffractometer. The adsorbents were used for a comparative study of Cr adsorption from aqueous solution. The obtained data were fitted to pseudo‐first order (PFO) and pseudo‐second order (PSO) models, the homogeneous fractal pseudo‐second order (FPSO), and the Weber–Morris intraparticle diffusion (IPD) kinetics models. Model parameters of the Langmuir and Freundlich adsorption isotherm models, as well as the thermodynamics, were calculated. Characterization results showed successful functionalizations. The GONH, GOSH, and GOSN exhibited alkaline, acidic, and neutral pH, respectively, in water. Amine and thiol functional groups were observed in the new adsorbents, as well as reduced orderliness. The adsorbents had higher density per unit weight and better thermal stability than pristine GO. Equilibrium Cr adsorption was attained within 60 min for all adsorbents. The PSO and FPSO described the rate data better. The Cr adsorption decreased as solution pH increased; optimum adsorption was recorded at pH 2. Equilibrium adsorption data fitted the Langmuir adsorption isotherm model for the GONH, while it fitted the Freundlich for both GOSH and GOSN. The adsorption process was theoretically exothermic process that was spontaneous processes. The Cr adsorption capacities of these adsorbents are 114, 89.6, and 173 mg/g for GONH, GOSH, and GOSN, respectively, and these were better than several reported graphene‐based adsorbents and suggest the potential of these adsorbents for water treatment.Practitioner points Graphene oxide was mono and dual‐functionalized with amine and thiol groups for Cr adsorption. The adsorption capacities of these adsorbents were better than several earlier reported. These adsorbents may be used for real contaminated water treatment.

Metals and Antibiotics as Aqueous Sequestration Targets for Magnetic Polyamidoamine-Grafted SBA-15

“…This band was absent in SBA-15-NH (Figure S2) but was slightly shifted to 560 cm –1 in mPSBA. This band as well as the characteristic bands linked to the SBA-15-NH and G-5 PAMAM dendrimers such as the amide-I bands , (CO, C–O, N–H) at ≈1634 cm –1 , Si–O bands , at ≈1045 and 800 cm –1 , and CH 2 /CH 3 bands ,, (≈2942 cm –1 ) were all expressed in the mPSBA composite material. Comparison of the pre/postadsorption spectra of the mPSBA materials showed slight shifts but intensified peaks around the amide-I and amide-II bands, , suggesting the likely points of adsorption of the contaminants on mPSBA.…”

“…The pH of the mPSBA composite and its precursor materials were examined in water (pHH 2 O) and 1.0 M KCl (pH KCl ), and the results are detailed in Table . This is vital because pH has effects on both the adsorbent and the contaminant surface charges and eventually adsorption process. , Pristine SBA-15 exhibited weakly acidic pH values for both the pHH 2 O and pH KCl , while the presence of the basic amine group on the SBA-15-NH variant conferred alkalinity to both pH values. The MNPs exhibited strongly alkaline pHH 2 O and pH KCl values (pH ≈11).…”

“…Though the FPSO model overestimated the quantities of contaminants adsorbed ( q e ), their better fitness parameters are strong indications that the data may be sufficiently described by this model, which suggests that the adsorption process of both contaminants on mPSBA involves more complex interactions than electrostatic interactions. It has been suggested that part of these complex interactions could include those between (a) the negatively charged OH – and COO – functional groups of the G-5 PAMAM and the Cd­(II) ions, and (b) oxygen-containing As­(III) species and the amine groups of the G-5 PAMAM, which could result in hydrogen bonding and/or electrostatic interactions, as well as pore-filling/contaminant trapping within pores because the composite is composed of a mesoporous SBA-15 component and π–π and weak van der Waals interactions. ,,, …”

Monitoring and Management of Anions in Polluted Aqua Systems: Case Studies on Nitrate, Chromate, Pertechnetate and Diclofenac

“…Interestingly, the surface areas of these materials are below 100 m 2 /g. The materials show an excellent to carbon-based materials such as those discussed above [153][154][155][156][157][158][159], which show high adsorption capacities at low pH but perform rather poorly at high pH.…”

“…Using a closely related approach, Nkutha et al [157] have made graphene-based sorbents by modification of graphene oxide with amino-and mercaptosilanes providing materials with -NH2 and -SH functional groups suitable for metal binding. The main outcome of the article is the observation that, analogous to the work by Mondal et al [156], the highest adsorption efficiencies were observed at pH 2.…”