Development of an innovative capsule with three-dimension honeycomb architecture via one-step titration-gel method for the removal of methylene blue
Graphical abstract
Introduction
Currently, urbanization and industrialization are deepening constantly, which raises the need of water and wastewater treatment experts to manage and treat a huge amount of contaminated waters with discharged toxic and harmful pollutants that are seriously destroying people's aquatic and the surrounding environment. Different physical, chemical and biological ways of removing these harmful pollutants from the aqueous environment have been drawn up and employed for controlling water pollution [[1], [2], [3]]. Among them, adsorption, has become fairly widely used; its rapid acceptance is due to the fact that it has overcome several of the drawbacks of conventional technologies, such as higher removed efficacy and cost efficiency [4,5].
In most studies of the adsorption, the adsorbed capacity of the adsorbents has been widely emphasized with attention being given to its real performance in application [6]. The previous work on this topic has indicated that the adsorptive performance of the nano-adsorbents, especially, graphene, is comparatively better than other materials due to possessing higher specific surface area and adsorbed sites, which is widely used for the removal of herbicides and metal ions, i.e., lead, cadmium and copper, etc., from the environment [[7], [8], [9], [10], [11]]. Nevertheless, it is very difficult to separate and recycle them from aqueous solutions after eliminating the contaminants because of their brilliant dispersibility [12,13]. It is also noticed that parts of graphene are directly/indirectly released into the environment, which not only pollutes the environment but also causes a waste of resources [14]. Widespread research indicates that it has negative influences on human health and ecological balance [[15], [16], [17]]. Nowadays, though some tasks have been started to find practical solutions to re-cycle the graphene materials after adsorption, the results are not always satisfactory. For example, graphene materials are separated from water through magnetic force or gravity after adsorption via loading them onto the magnetic or other larger nanoparticles, but its adsorbed capacity is seriously demolished in this progress [[18], [19], [20]]. Also, high-speed centrifuge has been used to collect the graphene after adsorption, but this technique is expensive and unrealistic for commercial sewage treatment [21].
By way of contrast, hydrogels are rich in hydrophilic functional groups such as carboxyl, amide, hydroxyl and sulfonic acid, and so on [[22], [23], [24]]. Based on this, they are successfully used for encapsulating and hybridizing some organic and inorganic materials to rapidly capture the pollutants from wastewaters, hold much water and can be permeated by oxygen and nutrients freely, etc. For instance, porous CTS-PVA/GO hydrogel is used for researching bone regeneration potential [25]; MNPs embedded in an SA/PVA matrix is applied to solve CMPW [26]; photo-catalysis efficiency of TiO2/poly [acrylamide-co-(acrylic acid)] composite material is used in the textile dye degradation [27]. Moreover, the inorganic nanoparticles can sufficiently interact with the radicals of the hydrogels then embed tightly into the polymers matrix, thereby minimizing the potential environmental damage which might be caused by the free-diffusion. However, most hydrogels are soft and vulnerable in adsorbed process. In addition, these hydrogels do not be provided with such polymer cellular pores as larger pore volume and higher porosity honeycomb architectures which have already described by the TIPS and NIPS methods for producing thin flat-sheets in spite of possessing multi-aperture and micro-porous pattern [[28], [29], [30], [31]]. Their weak chemical stability, low surface area and the porosity severely restrict their adsorption properties [32,33].
It is reported that the organic-inorganic composite hydrogels with IPNs structure have more excellent performance in a series use [34,35]. In addition, the mechanical property of the hydrogel could be further improved after chemical and physical modification [36]. On the basis of existing literature data, we carried out the studies in an effort to prepare the hybrid hydrogel adsorbents with specialized porous morphology, chemical stability and low toxicity, which can be recycled and applied to the overly acid or alkali situation. Herein, to the best of the knowledge of the researchers in this research, it was the very first time to present this novel capsule absorbent with 3D honeycomb architecture just through the one-step titration-gel method by injecting PVA and SA-GO spheroidal sol into the CaCl2 and oversaturated H3OB3 mixture, and these capsules were modified by GA then. The robust capsule loaded with GO could be reused for MB adsorption for at least 6 times by washing with acid eluent and water.
Section snippets
Materials
PVA (MW 146,000–186,000, 99+% hydrolyzed) was purchased from Sigma-Aldrich. GA (50.0 vol% in H2O) was applied by Aladdin Reagents Co., Ltd. (China). Commercial GO (Single layer GO powder, diameter 0.8 nm–1.2 nm, thickness 0.5 μm–5 μm) were obtained from XFNANO Co., Ltd. (China). Other chemicals were supplied by Sinopharm Chemical Reagent Co., Ltd. (China) and used as received. The ultra-pure water was produced by a Milli-Q BIOCEL unit (Millipore, The USA) with the resistivity of 18 MΩ cm.
Preparation of the casting sol
At
Morphology analysis of the prepared capsules
The FE-SEM analysis was conducted for clear depicting the morphology transmutation of the prepared capsules from the surface to the interior (Fig. 2, A to C).
Generally, from A to C, the overall microscopic-morphology of the prepared capsules exhibited distinct “3D honeycomb” architectures (Fig. 3). Moreover, the fenestra population and the diameter of the capsules were varied from ‘dense and small’ to ‘sparse and large’, which displayed a cascade distribution. The reason behind the results
Conclusion
In summary, the formation mechanism of the capsules contained a chelation process that the sol of the PVA-SA-GO was covalently bonded with H3BO3 and CaCl2. GA could co-cross-link with the polymer and had a brilliant ‘healing’ potency to regrow and reinforce the fractured fibers of the capsules, which increased the density of the pores and narrowed the average pore size distribution of the capsules. The capsule with faviform architectures and wide pH tolerance nature in this research could be
Acknowledgments
The authors acknowledge the support of the Key Project of the Joint Fund Between the State Fund Committee and Shandong Province (U1806210) and the State Key Laboratory of Environmental Criteria and Risk Assessment (SKLECRA2013FP12).
References (46)
- et al.
A versatile CeO2/Co3O4 coated mesh for food wastewater treatment: simultaneous oil removal and UV catalysis of food additives
Water Res.
(2018) - et al.
Seasonal performance of a full-scale wastewater treatment enhanced pond system
Water Res.
(2018) - et al.
Biofouling of membrane distillation, forward osmosis and pressure retarded osmosis: principles, impacts and future directions
J. Membr. Sci.
(2017) - et al.
Development of bubble absorption refrigeration technology: a review
Renew. Sust. Energ. Rev.
(2018) A review on the adsorption of heavy metals by clay minerals, with special focus on the past decade
Chem. Eng. J.
(2017)- et al.
Simultaneous removal of heavy metals from field-polluted soils and treatment of soil washing effluents through combined adsorption and artificial sunlight-driven photocatalytic processes
Chem. Eng. J.
(2016) - et al.
TiO2/porous adsorbents: recent advances and novel applications
J. Hazard. Mater.
(2018) - et al.
Recent progress and future challenges on the use of high performance magnetic nano-adsorbents in environmental applications
Chem. Eng. J.
(2014) - et al.
Nanocomposites of graphene oxide-hydrated zirconium oxide for simultaneous removal of as(III) and as(V) from water
Chem. Eng. J.
(2013) - et al.
Graphene oxide-cation interaction: inter-layer spacing and zeta potential changes in response to various salt solutions
J. Membr. Sci.
(2018)
Magnetic TiO2-graphene composite as a high-performance and recyclable platform for efficient photocatalytic removal of herbicides from water
J. Hazard. Mater.
Photochlorination-induced transformation of graphene oxide: mechanism and environmental fate
Water Res.
Bromate inhibition by reduced graphene oxide in thermal/PMS process
Water Res.
Ultra-trace graphene oxide in a water environment triggers Parkinson's disease-like symptoms and metabolic disturbance in zebrafish larvae
Biomaterials
Synergistic coagulation of GO and secondary adsorption of heavy metal ions on ca/Al layered double hydroxides
Environ. Pollut.
Water and ion sorption, diffusion, and transport in graphene oxide membranes revisited
J. Membr. Sci.
Recent advances in graphene-based magnetic composites for magnetic solid-phase extraction
TrAC Trends Anal. Chem.
Green synthesis of magnetic MOF@GO and MOF@CNT hybrid nanocomposites with high adsorption capacity towards organic pollutants
Chem. Eng. J.
Development of bi-metal doped micro- and nano multi-functional polymeric adsorbents for the removal of fluoride and arsenic(V) from wastewater
Desalination
A facile and controllable method to encapsulate phase change materials with non-toxic and biocompatible chemicals
Appl. Therm. Eng.
Shape memory polymer-based hybrid honeycomb structures with zero Poisson's ratio and variable stiffness
Compos. Struct.
Magnetic alginate beads for Pb(II) ions removal from wastewater
J. Colloid Interface Sci.
Bio-inspired layered chitosan/graphene oxide nanocomposite hydrogels with high strength and pH-driven shape memory effect
Carbohydr. Polym.
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