Atian Xie

Hollow imprinted polymer nanorods with a tunable shell using halloysite nanotubes as a sacrificial template for selective recognition and separation of chloramphenicol

The wide use of antibiotics in human therapy and veterinary practice has resulted in the presence of residual antibiotic compounds in water environments, which are harmful to ecology and health. In this work, novel hollow molecularly imprinted nanorods (HMINs) with uniform and controllable thickness of the polymer shell were successfully prepared via a combination of in situ surface precipitation polymerization and halloysite nanotubes sacrificial template method, and were used as an advanced selective nanoadsorbent to remove chloramphenicol (CAP). The physicochemical properties of HMINs were well characterized by FE-SEM, TEM, FT-IR and TG/DTA. HMINs with a shell thickness of 62 nm (HMINs-2) displayed excellent adsorption capacity and fast kinetics. The experimental adsorption equilibrium and kinetic data were best described by the Freundlich isotherm model and the pseudo-second-order rate equation, respectively. Furthermore, HMINs-2 possessed highly specific recognition to CAP in aqueous solutions, as compared with other reference antibiotics. Meanwhile, HMINs-2 also had excellent dispersibility, regeneration properties and thermal stability for the promising potential application in wastewater treatment.

Preparation of highly porous carbon from sustainable α-cellulose for superior removal performance of tetracycline and sulfamethazine from water

Hierarchical carbon materials with ultrahigh specific surface area and high porosity were synthesized by KOH activation from sustainable α-cellulose and employed as adsorbents to study adsorption performance of tetracycline (TC) and sulfamethazine (SMZ) from aqueous solutions. The physical and chemical properties of the as-prepared materials were characterized by SEM, TEM, FT-IR, XPS, Raman and a surface area analyzer. The obtained porous carbon exhibited a hierarchical pore structure, large BET specific surface area (3187.91 m2 g−1) and pore volume (1.781 cm3 g−1) when the activation temperature reached 850 °C. The maximum adsorption capacities were 1072.86 and 786.18 mg g−1 for TC and SMZ removal at 298 K, respectively. Moreover, TC and SMZ showed similar adsorption features, kinetic results could fit well using a pseudo-second-order model, intraparticle diffusion was not the rate-controlling step and adsorption isotherm results fit well with the Langmuir model. The adsorption capacities increased with contact time and adsorption temperature and, moreover, pH and external ionic species have a significant effect on adsorption efficiency. Thermodynamic studies implied that physisorption might dominate adsorption and the adsorption process is spontaneous and thermodynamically favorable. The results are of importance to indicate that the as-prepared porous carbon could be used as a low-cost and effective adsorbent in pharmaceutical wastewater treatment.

Designed preparation of 3D hierarchically porous carbon material via solvothermal route and in situ activation for ultrahigh-efficiency dye removal: adsorption isotherm, kinetics and thermodynamics characteristics

Herein, the first preparation of a novel 3D hierarchically porous carbon (3D HPC) via precarbonization and in situ alkali activation, wherein mesoporous polydivinylbenzene (meso-PDVB) synthesized by a facile and general solvothermal route was used as the carbon precursor, is reported. Its physico-chemical properties were characterized by SEM, TEM, XRD, FT-IR, elemental analysis, Raman spectroscopy and N2 adsorption–desorption isotherm. 3D HPC exhibited a very large SSA of 3131.32 m2 g−1 and a pore volume of 1.462 cm3 g−1. Moreover, 3D HPC was used to eliminate a dye from wastewater for the first time. The effects of the contact time, initial dye concentration, temperature and solution pH on the adsorption of methylene blue (MB) onto 3D HPC were investigated by batch techniques. The isotherm and kinetics data were well described by a Langmuir model and a pseudo-second-order kinetic model, respectively. 3D HPC had a high adsorption affinity for MB over a broad pH range. 3D HPC displayed remarkably strong adsorption of MB, with a maximum adsorption capacity of 717.77 mg g−1 at 308 K. The adsorption process was endothermic and spontaneous, and the kinetics was controlled by film and intra-particle diffusion. The mechanism of the adsorption of MB was mainly attributed to van der Waals forces, π–π stacking and electrostatic interactions. In addition, 3D HPC displayed excellent reusability and exhibited promising potential for the treatment of dyes in wastewater.

Converting obsolete copy paper to porous carbon materials with preeminent adsorption performance for tetracycline antibiotic

To date, the employment of developed adsorbents in antibiotic wastewater treatment practices is still limited due to their low adsorption capacity, slow kinetics and especially high cost. Thus, in this work, we first report the conversion of obsolete copy paper to highly porous carbon materials (PCMs) via a two-step method: low-temperature carbonization and alkali activation. The influence of activation temperature and KOH content on the porosity and adsorption capacity of PCMs was also studied. Notably, copy paper (CP) is consumed in extremely large quantities with a high proportion being obsoleted; it mainly consists of micro- and nano-cellulose fibers that can be used as an ideal carbon source. The PCMs were characterized by several techniques and methodologies. The PCMs-850-4 exhibited an ultrahigh BET surface area of 3598.95 m2 g−1 and total pore volume of 1.887 cm3 g−1. The influence of temperature, initial concentration, contact time, pH and ionic strength on the adsorption of tetracycline (TC) from water to PCMs-850-4 was investigated through batch adsorption studies. Analyses of adsorption isotherm, kinetics and thermodynamics property were conducted to understand the adsorption behavior. The equilibrium experimental data was well fitted to the Langmuir model, and the kinetic data was best described by the pseudo-second-order rate model. Importantly, the PCMs-850-4 displayed an ultrahigh adsorption of 1437.76 mg g−1 at 298 K, and increasing temperature benefited the adsorption. Also, their fast kinetics and great regeneration make the PCMs-850-4 a promising adsorbent for the low-cost, highly efficient and fast removal of organic pollutants from water environments.

A biomimetic Setaria viridis-inspired imprinted nanoadsorbent: green synthesis and application to the highly selective and fast removal of sulfamethazine

Nowadays, it is very necessary to develop high-efficiency nanoadsorbents to remove drug contaminants from wastewater. Inspired by a biomimetic Setaria viridis-like structure, we provide a simple and general approach for the preparation of hydrophilic magnetic surface molecularly imprinted core–shell nanorods (HMMINs) via a two-step surface-initiated atom transfer radical polymerization in a green alcohol/water solvent mixture at room temperature, with magnetic halloysite nanotubes (HNTs, a hollow tubular structured natural clay mineral) used as nano-cores. HMMINs showed a well-defined core–shell structure with an ultra-thin imprinted film (12 nm) and hydrophilic polymer brushes (2–4 nm), where magnetic nanoparticles (11 nm) were uniformly dispersed onto the surface of halloysite nanotubes. HMMINs possess good magnetic properties and thermal stability. Surface grafting of the hydrophilic polymer brushes enhanced the adsorption selectivity and kinetics. HMMINs exhibited a large adsorption capacity (37.64 ± 1.36 μmol g−1) and fast kinetics (within 45 min) towards a typical antibiotic drug sulfamethazine (SMZ) from pure water. Adsorption isotherm and kinetics data were well described by the Freundlich isotherm model and pseudo-second-order kinetic equation, respectively. HMMINs displayed good selectivity towards SMZ as compared with other antibiotics, as well as good regeneration performance, providing a potentially practical application in the highly efficient and selective removal of antibiotic contaminants from wastewater.

Facile preparation of intercrossed-stacked porous carbon originated from potassium citrate and their highly effective adsorption performance for chloramphenicol

Recently, antibiotics pollution has attracted more interests from many researches which causes potential risks on the ecosystem and human health. Herein, the porous carbons (PCs) was prepared by directly simultaneous carbonization/self-activation of potassium citrate at 750-900°C for chloramphenicol (CAP) removal from aqueous solution. The batch experiments were studied, which indicated that PCs prepared at 850°C, namely PCPCs-850, possessed excellent adsorption ability for CAP with a maximum adsorption amount of 506.1mgg-1. Additionally, PCPCs-850 showed a large BET surface area of 2337.06m2g-1 and microporosity of 89.11% by N2 adsorption-desorption experiment. The Langmuir and pseudo-second-order model could more precisely describe the experimental data. And thermodynamic analysis illustrated that CAP adsorption onto PCPCs-850 was an endothermic and spontaneous process. Importantly, the adsorbent exhibited good stability and regeneration after four times cycles. Based on these excellent performance, it is potential that PCPCs-850 can be used as a promising adsorbent for treating contaminants in wastewater.

Hierarchical porous carbon materials derived from a waste paper towel with ultrafast and ultrahigh performance for adsorption of tetracycline

Herein, waste paper towels, a mass garbage product from daily life, were used as precursors for the production of hierarchical porous carbon (PTHPC) via KOH activation to be used for the removal of tetracycline. In this study, the influence of KOH content on porosity and adsorption capacity was investigated, and the optimal property of hierarchical porous carbon was obtained at weight ratios of carbonization: KOH = 1 : 4 (PTHPC-4). The physico-chemical properties of PTHPC-4 were characterized by different technology. Notably, PTHPC-4 possesses an ultrahigh specific surface area of 3524 m2 g−1 and a large pore volume of 1.839 cm3 g−1. Additionally, the isothermal adsorption results showed that PTHPC-4 displayed an ultrahigh adsorption capacity of 1661.13 mg g−1 for tetracycline, which is superior to other previously reported adsorbents. Moreover, PTHPC-4 also has excellent kinetics performance: when C0 = 100 mg L−1, the pseudo-second-order kinetics constant k2 values at 298, 308 and 318 K are 1.055 × 10−2, 5.731 × 10−2 and 8.916 × 10−2 g mg−1 min−1, respectively, which were 1–3 magnitude higher than previously reported adsorbents. In addition, the investigation of the effect temperature, pH and ionic strength on the adsorption property for tetracycline are included in this study.

Magnetic organic–inorganic nanocomposite with ultrathin imprinted polymers via an in situ surface-initiated approach for specific separation of chloramphenicol

An approach for preparing novel magnetic organic–inorganic nanocomposites with ultrathin imprinted polymers was reported, via an in situ surface-initiated grafting technique from magnetic halloysite nanotubes (MHNTs). These magnetic surface molecularly imprinted nanomaterials (MMINs) were used as advanced nanoadsorbents for specific separation of chloramphenicol (CAP) from water. The thickness of the imprinted polymer was well controlled by adjusting the addition amount and solvent volume. The optimal conditions for adsorption performance of MMINs included using methacrylic acid (MAA) as a functional monomer, and a ratio of MMA:CAP was 1:6 with an acetonitrile volume of 15 mL, which showed an ultrathin imprinted nanoshell of 8.5 nm. The ultrathin imprinted nanoshell made all the imprinted cavities efficient and easily accessible. Thus, MMINs exhibited fast adsorption kinetics with equilibrium time of about 20 min. The adsorption equilibrium and kinetic data could be well described by the Freundlich isotherm model and pseudo-second-order kinetic model, respectively. MMINs had an excellent specific adsorption capacity of CAP from water compared with other antibiotics. Also, MMINs exhibited excellent regeneration properties and stability, as well as good magnetic separation, providing the possibility for practical antibiotic wastewater treatment.

Surface hydrophilic imprinted particles via a green precipitation polymerization for selective removal of tetracycline from aqueous solution

In this research, hydrophilic molecularly imprinted polymers (HMIPs) were synthesized through a facile one-step green precipitation polymerization in ethanol, which was non-toxic, green and environmentally friendly. HMIPs were tested by FT-IR, SEM, water contact angle studies and water dispersion stability test. HMIPs exhibited a good water-compatibility property. Compared with non-imprinted process, template molecule tetracycline (TC) had a significant influence on morphology of polymer particles. Batch binding experiments were carried out in water to evaluate adsorption equilibrium, kinetics and selectivity. Equilibrium adsorption amount increased with the increase of the temperature, and the data were well described by Freundlich model. Kinetics properties of HMIPs were better fitted to pseudo-second-order rate equations. The thermodynamic analysis indicated that the adsorption process of TC was spontaneous and endothermic. HMIPs exhibited the high affinity and selectivity toward TC over structurally analogous antibiotics than that of non-imprinted polymers. Also, the HMIPs had good reuse ability.

Preparation of macroscopic spherical porous carbons@carboxymethylcellulose sodium gel beads and application for removal of tetracycline

The development of practicable and retrievable adsorbents with high adsorption capacity is a technical imperative for water treatment. Herein, we reported a new convenient macroscopic granular adsorbent for the removal of tetracycline (TC) from water by immobilizing porous carbons (PCs) which were obtained via one-step in situ pyrolysis from ethylenediaminetetraacetic acid dipotassium salt dihydrate (EDTA-2K·2H2O) into carboxymethylcellulose sodium (CMCS) gel beads utilising molecular cross-linking. A remarkable similarity can be observed between multivariant gel beads and EDTA-2K·2H2O derived porous carbons (EPCs) according to the characterization results. The adsorption performance was evaluated using batch adsorption studies of TC in aqueous solution: the kinetic results could be fit well by a pseudo-second-order model and intraparticle diffusion was treated as the rate-controlling step; equilibrium adsorption data fitted well to the Langmuir adsorption isotherm yielding a maximum adsorption capacity of 136.9 mg g−1 at 298 K. Importantly, these results indicate that the as-prepared gel beads could be used as facile adsorbents in pharmaceutical wastewater treatment.