Adsorption and kinetic study of Cr(VI) on ZIF-8 based composites

Abstract

In this study, adsorption of hexavalent chromium has been examined on ZIF-8 and its various composites. ZIF-8 was modified by using amine groups, GO and Mg(OH) 2 /GO. ZIF-8, Mg(OH) 2 /GO, ZIF-8/NH 2 , ZIF-8/Mg(OH) 2 /GO, ZIF-8/NH 2 /GO and ZIF-8/NH 2 /Mg(OH) 2 /GO was studied for Cr(VI) adsorption Several characterization techniques were used for the structural and surface characterization such as Fourier transform infrared spectroscopy (FTIR), x-ray diffraction (XRD), scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) surface area analyzer. The impact of various adsorption parameters (contact time, pH, initial concentration of Cr(VI) and absorbent dosage) was studied in batch experiments. Different kinetic and isotherm models were applied on equilibrium data. The adsorption process of ZIF-8 and its composites was explained by pseudo-second-order kinetic model as well as Langmuir isotherm, with maximum removal efficiency of 98% for Cr(VI) by ZIF-8/NH 2 /Mg(OH) 2 /GO. OPEN ACCESS RECEIVED

Sustainable Application of ZIF-8 for Heavy-Metal Removal in Aqueous Solutions

“…From Equation (1), C 0 is the initial concentration, C e is the equilibrium concentration for the adsorbate in solution, v equals the volume of solution, m is the mass (mg) of the adsorbent, and Q e is the equilibrium adsorption value, used to determine the adsorption capacity of the adsorbent [27]. From equation (2), C i (mg/l) in the determination of removal efficiency is the initial concentration and C f (mg/l) is the final concentration of metal ions in the treated effluent [27,38]. The efficiency of the adsorbent is typically described using adsorption-equilibrium isotherms as well as kinetic models.…”

“…In both experiments, although ZIF-8 showed a distinctive selectivity towards Cu 2+ , the adsorption capacity of ZIF-8 in the removal of these binary heavy metals was exceptionally high [32]. Begum et al [38] also used ZIF-8 as a nanocomposite membrane with magnesium hydroxide (Mg(OH) 2 ), graphene oxide, and amine groups for Cr(VI). They obtained a maximum removal efficiency of 98% of Cr(VI) at an adsorption equilibrium of 4.88 mg g −1 [38].…”

“…Begum et al [38] also used ZIF-8 as a nanocomposite membrane with magnesium hydroxide (Mg(OH) 2 ), graphene oxide, and amine groups for Cr(VI). They obtained a maximum removal efficiency of 98% of Cr(VI) at an adsorption equilibrium of 4.88 mg g −1 [38].…”

“…In many cases, there will be more than one mechanism responsible for the high adsorptive capabilities of ZIF, such as diffusion, hydrogen bonding, and electrostatic interactions [2,[44][45][46]. In a study by Begum et al [38], the surface of ZIF-8 was positively charged because =N−, −NH− and −NH 2 groups of imidazolate ligands were protonated in an aqueous system, which provided an electrostatic interaction for Cr(VI) for adsorption. The bonding of hydroxyl groups to zinc and the presence of GO and Mg (OH) 2 also strengthened interactions with Cr(VI), further reducing it to Cr(III), partially.…”

Fire-Safe Polymer Composites: Flame-Retardant Effect of Nanofillers

“…Nanoparticulate zeolitic imidazolate famework-8 (nano-ZIF-8) have been also used to develop flame retardants [ 233 , 234 , 235 , 236 , 237 ]. Recently, as shown in Figure 35 [ 238 ], a new flame retardant based on nanoparticulate zeolitic imidazolate framework-8 (nano-ZIF-8) and dried distillers grains with solubles (DDGS) was designed, without any conventional flame retardants, and blended with polypropylene (PP) to obtain an environmentally friendly flame-retardant composite [ 233 , 234 , 235 , 236 , 237 ]. The LOI of the composite containing 27 wt% DDGS and 3 wt% nano-ZIF-8 (avg.…”