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This study aimed to explore the co-removal effect and mechanism of Cr(VI) and Cd(II) with an optimized synthetic material. The toxicity and accumulation characteristics of Cr(VI) and Cd(II) encountered in wastewater treatment areas present significant challenges. In this work, a rational assembly of sulfide-modified nanoscale zero-valent iron (SnZVI) was introduced into a biochar (BC), and a Cr(VI)–Cd(II) binary system adsorbent with high efficiency was synthesized. When the preparation temperature of the BC was 600 °C, the molar ratio of S/Fe was 0.3, the mass ratio of BC/SnZVI was 1, and the best adsorption capacities of BC-SnZVI for Cr(VI) and Cd(II) in the binary system were 58.87 mg/g and 32.55 mg/g, respectively. In addition, the adsorption mechanism of BC-SnZVI on the Cr(VI)-Cd(II) binary system was revealed in depth by co-removal experiments, indicating that the coexistence of Cd(II) could promote the removal of Cr(VI) by 9.20%, while the coexistence of Cr(VI) could inhibit the removal of Cd(II) by 43.47%. This work provides a new pathway for the adsorption of Cr(VI) and Cd(II) in binary systems, suggesting that BC-SnZVI shows great potential for the co-removal of Cr(VI) and Cd(II) in wastewater. [ABSTRACT FROM AUTHOR]

Highly efficient removal of bilirubin from blood by hemoperfusion for liver failure therapy remains a challenge in the clinical field due to the low adsorption capacity and slow adsorption kinetics of currently used bilirubin adsorbents (e.g., activated carbon and ion‐exchange resin). Recently, porous aromatic frameworks (PAFs) with high surface areas, tunable structures, and remarkable stability provide numerous possibilities to obtain satisfying adsorbents. Here, a cationic PAF with more mesopores, named iPAF‐6, is successfully constructed via a de novo synthetic strategy for bilirubin removal. The prepared iPAF‐6 exhibits a record‐high adsorption capacity of 1249 mg g−1 and can adsorb bilirubin from 150 mg L−1 to normal concentration in just 5 min. Moreover, iPAF‐6 shows a removal efficiency of 96% toward bilirubin in the presence of 50 g L−1 bovine serum albumin. It is demonstrated that positively charged aromatic frameworks and large pore size make a significant contribution to its excellent adsorption ability. More notably, iPAF‐6/polyethersulfone composite fibers or beads are fabricated for practical hemoperfusion adsorption, which also show better removal performance than commercial adsorbents. This work can offer a new possibility for designing PAF‐based bilirubin adsorbents with an appealing application prospect. [ABSTRACT FROM AUTHOR]

[Display omitted] • La 2 (CO 3) 3 /CoFe 2 O 4 /biochar (LCB) was synthesized by a hydrothermal process. • LCB/PMS system was established to remove P(III) in one step. • LCB/PMS exhibited satisfactory removal rate of P(III) in a wide pH range. • SO 4 •- played a critical role in the oxidation process. • Different types of phosphorus could be rapidly removed by LCB/PMS. Phosphite [P(III)], an emerging eutrophication pollutant, has attracted limited attention in recent years. Owing to the higher solubility and resistance to biotransformation of P(III), oxidation of P(III) to phosphate [P(V)] is considered to be necessary to enhance P(III) removal. Herein, an efficient and regenerable magnetic La 2 (CO 3) 3 /CoFe 2 O 4 /biochar composite (LCB) was constructed through a facile one-pot hydrothermal method to treat phosphite-laden wastewater. LCB coupled with peroxymonosulfate (PMS) exhibited satisfactory P(III) removal performance through a one-step process for simultaneous oxidation and adsorption of P(III). The adsorption capacity of LCB/PMS for P(III) (71.94 mg/g) was much higher than that of LCB. LCB/PMS system showed high P(III) removal efficiency of 96.62 %, wide pH ranging from 4.0 to 9.0, and good reusability. It also worked well in the existence of anions and humic acid. The quenching experiments and electron spin resonance tests (ESR) revealed the critical role of SO 4 •- in the P(III) oxidation process. Characterization results demonstrated that electrostatic attraction and ligand exchange were responsible for P(III)/P(V) adsorption. Moreover, LCB/PMS system presented desirable performance in eliminating a series of typical organic and inorganic phosphorus. The LCB/PMS system provides a promising and sustainable technology for the purification of P(III)-contaminated water. [ABSTRACT FROM AUTHOR]

MOF-5@SiO 2 and IRMOF-10@SiO 2 with different pore sizes and shell thicknesses were synthesized by a layer-by-layer method and used to explore the effects of pore size on dye adsorption behaviour. The characterization results indicated that shell thickness could dramatically influence pore structure. Mesopores and macropores in MOFs@SiO 2 existed when the synthetic cycles were less than 10, while micropores could be obtained when MOFs@SiO 2 were prepared after 20cycles. The adsorption kinetic and isotherm results showed that adsorption of basic fuchsin onto MOF-5@SiO 2 increased but the adsorption capacities decreased with increasing shell thickness. The adsorption rate of basic fuchsin on IRMOF-10@SiO 2 was lower and the adsorption capacity was higher than that of MOF-5@SiO 2. Meanwhile, the adsorption rates of IRMOF-10@SiO 2 decreased, but the capacities increased as the shell thickness increased. Moreover, Fourier transform infrared and X-ray photoelectron spectroscopy were used to investigate possible adsorption mechanisms. The results suggested that basic fuchsin could enter the pores of IRMOF-10@SiO 2 but could not enter MOF-5@SiO 2 due to the size-exclusion effect. The illustration of BF adsorption modes in MOF-5@SiO 2 and IRMOF-10@SiO 2 and their adsorption performance at different shell thickness. Image 1 • Preparation of MOFs@SiO 2 using layer-by-layer method. • Shell thickness plays a crucial role in morphology & pore structures of MOFs@SiO 2. • Regulation of shell thickness MOFs@SiO 2 to improve capacity and selectivity. • Size exclusion effect was a key factor which effect the adsorption behaviour. • Electric charge effect, benzene ring of IRMOF-10@SiO 2 provided interaction sites. [ABSTRACT FROM AUTHOR]

• MOFs are incorporated in chitosan beads uniformly and stably. • The MOFs are synthesized from metal hydroxide(or metal oxide) in situ. • The MOF loading can be controlled by changing the metal amount in the precursor. • ZIF-8-chitosan beads exhibit the adsorption capacity of 495.04 mg/g for tetracycline. • The beads can treat ~887 bed volumes of tetracycline solution in real water sample. Metal-organic frameworks (MOFs) have been attractive adsorbents for the treatment of antibiotic wastewater. However, in their powder form, the adsorbents suffer from the disadvantage of poor recyclability and complex operational process. Herein, we incorporated typical MOFs (ZIF-8, ZIF-67, HKUST-1, and Fe-BTC) into low-cost chitosan matrix for the tetracycline removal. Metal hydroxide(or metal oxide)/chitosan composite beads from the metal salt/chitosan solution were used as MOF precursor, which lead to the uniform and stable MOF loading into chitosan. This composition could not only shape MOFs into beads but also improve the adsorption capacity of the chitosan. As a result, ZIF-8-chitosan composite beads exhibited good adsorption performance toward antibiotic tetracycline. The adsorption processes followed pseudo-second-order model and Langmuir isotherm model. The maximum adsorption capacity could reach 495.04 mg/g, which is higher than most of the MOF-based or natural polymer-based tetracycline adsorbents. Moreover, the removal efficiency of ZIF-8-chitosan composite beads toward tetracycline was still above 90% after ten adsorption-desorption cycles. In the fixed-bed experiment, ZIF-8-chitosan column could treat ~887 bed volumes (BV) of tetracycline solution in real water sample. Both experimental characterizations and DFT calculations indicated that the adsorption mechanism involves in the electrostatic interaction, π-π stacking interaction and hydrogen-bonding interaction. This study provides a promising strategy for uniform MOF loading into the matrix and potential adsorbents for pharmaceutical wastewater treatment. [ABSTRACT FROM AUTHOR]

The solid-liquid separation ability of adsorbents is of great significance for improving the recovery efficiency and reducing the cost. Herein, a novel floating-magnetically responsive silica adsorbent (FMSA) was prepared and applied to the adsorption of cationic dyes from aqueous solution. FMSA with self-floating and magnetic response properties exhibited great solid-liquid separation ability and adsorption performance for cationic dyes. According to the Langmuir model, the theoretical saturated adsorption capacity of FMSA for Basic Blue 7 (BB-7) and Crystal Violet (CV) reached 1632.55 mg g−1 and 1587.23 mg g−1, respectively. Thermodynamic experiments manifested that the adsorption was a spontaneous endothermic process with increasing entropy. After 5 adsorption-desorption processes, FMSA's adsorption capacity for BB-7 and CV remained above 80%, indicating that it has satisfactory stability and reusability. Furthermore, the pH effect, isotherm, kinetics, ion interference experiments and characterization analysis manifested that the adsorption was mainly chemical adsorption with an ion exchange process. This research aims to bring some inspiration for the combined use of floating separation and magnetic separation to achieve more flexible, efficient and energy-saving solid-liquid separation. [Display omitted] • A floating-magnetically responsive silica adsorbent was successfully developed. • Obtained adsorbent has both self-floating ability and magnetic response properties. • FMSA showed great reusability and resistance to ion interference. • BB-7 and CV were efficiently removed in a wide pH range. • Powerful electrostatic interaction and ion exchange ensure efficient adsorption. [ABSTRACT FROM AUTHOR]

In order to deal with the increasingly serious water pollution caused by dye wastewater, a novel sulfonic acid-modified polyacrylamide magnetic composite (Fe 3 O 4 @SiO 2 /P(AM-AMPS)) was facilely prepared by crosslink reaction. The physicochemical properties and adsorption performances of Fe 3 O 4 @SiO 2 /P(AM-AMPS) were systematically studied by different characterization techniques and a series of batch experiments, respectively. It was found that the adsorption capacities of Fe 3 O 4 @SiO 2 /P(AM-AMPS) towards cationic dyes crystal violet (CV) and methylene blue (MB) were largely enhanced than those of silica-coated Fe 3 O 4 (Fe 3 O 4 @SiO 2) and maintained at relatively high levels in a wide pH range, due to the three-dimensional network structure and abundant functional groups of modified polyacrylamide. Besides, owing to the introduction of Fe 3 O 4 @SiO 2 , Fe 3 O 4 @SiO 2 /P(AM-AMPS) presented a unique magnetic property that helped it to be rapidly separated from water in a magnetic field. The maximum adsorption capacities of Fe 3 O 4 @SiO 2 /P(AM-AMPS) were 2106.37 mg g−1 for CV removal and 1462.34 mg g−1 for MB removal at 298.15 K, much higher than those of other reported magnetic composites. Furthermore, Fe 3 O 4 @SiO 2 /P(AM-AMPS) was effectively regenerated with HCl solution and the regeneration rates were higher than 97% and 80% for CV and MB removal after five adsorption-desorption cycles, respectively. With its excellent adsorption capacity, wide pH applicability, high separation speed, and satisfactory regeneration ability, Fe 3 O 4 @SiO 2 /P(AM-AMPS) was expected to become a promising adsorbent in the purification of cationic dye wastewater. Unlabelled Image • Novel PAM-based magnetic composite was facilely prepared by crosslink reaction. • Fe 3 O 4 @SiO 2 /P(AM-AMPS) presented a wide pH applicability for cationic dyes removal. • The maximum adsorption capacities were 2106 mg g−1 for CV and 1462 mg g−1 for MB. • The superior adsorption ability was attributed to multiple adsorption mechanisms. • Unique magnetism and good reusability facilitated its practical application. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hyperbranched phosphate groups were grafted onto electrospun nanofibers. • The proton transfer process could lead to the zwitterionic structures. • The fiber adsorbents exhibited excellent adsorption performance towards UO 2 2+. • The nanofibers also showed anti-bacterial adhesion and anti-protein adhesion. • The fiber adsorbents had good potential for the uranium extraction from seawater.. The development of efficient adsorbents with anti-biofouling properties for uranium extraction from seawater is highly attractive to meet the growing demands for energy. However, traditional fiber adsorbents still suffer from the challenge of weak binding energy, low functional group density, and inefficient antifouling ability. Herein, inspired by the structures of phospholipid, the bio-inspired zwitterionic phosphate groups were created onto the electrospun nanofibers to manipulate the affinity with uranium and the anti-biofouling property. Additionally, hyperbranched grafting reaction together with thin diameters of the fibers were applied to significantly improve the available density of functional groups. The constructed hyperbranched zwitterionic phosphate groups functionalized nanofiber adsorbents (ZP-PAN fibers) exhibited high distribution coefficient k d (7.38 × 106 mL/g) and large adsorption capacity (1294.0 mg g−1) in the uranium-spiked seawater, surpassing most of reported polymeric adsorbents. ZP-PAN fibers also showed good selectivity against competitive cations and stable reusability. Owing to their zwitterionic structures, ZP-PAN fibers had satisfactory anti-adhesive ability toward bacteria and protein. Consequently, the uranium could be effectively extracted by ZP-PAN fibers from natural seawater with the extraction capacity of 8.1 mg g−1 after contacting with seawater for 15 days. This work demonstrates a new functionalization selection for nanofiber materials and provides a promising adsorbent in the practical uranium extraction from seawater. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel cationic electrospun nanofibers (NCE fibers) were designed and synthesized. • Specific anion traps with hydrophobic microenvironment were constructed. • NCE fibers exhibited fast kinetics and high uptake for ReO 4 −. • NCE fibers showed good removal depth and satisfying selectivity toward ReO 4 −. • The column adsorption was also conducted with the treatment capacity of 1540 BV. Developing cationic adsorbents for efficient radioactive pertechnetate (99TcO 4 −) removal from water is of great significance in both nuclear fuel management and nuclear-related environmental treatment fields. However, tremendous efforts should be taken to improve the comprehensive performance of the adsorbent materials. Herein, novel cationic electrospun nanofibers were synthesized via the blending electrospinning from the branched polyethylenimine based solution and the following quaternization reaction by benzyl bromide. Consequently, abundant specific anion traps with hydrophobic microenvironment were constructed on the fibers. The obtained fiber adsorbents were systematically investigated to remove perrhenate (ReO 4 −) ions (the nonradioactive surrogate for TcO 4 −), which exhibit satisfying adsorption performance in several aspects: high adsorption capacity (943 mg g−1), fast kinetics (30 min), good removal depth (distribution coefficient = 1.1 × 106 mL g−1), large dynamic column adsorption volume (1540 bed volume), and excellent ReO 4 − capture from solution with high ionic strength or acidity/alkalinity. The adsorption performance surpassed all macroscopic shapeable adsorbents and many powdery advanced porous materials, owing to their abundant adsorption sites, tailored anion traps and macroscopic fibrous structures. Overall, this work gives a useful insight into designing novel adsorbents for effective TcO 4 −/ReO 4 − capture. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new magnetic composite of FSNCS/SDBS was synthesized at low temperature. • FSNCS/SDBS shows excellent adsorption performance for CIP. • FSNCS/SDBS shows wide pH adaptability. • SDBS enhances CIP's adsorption by improving the surface charge of FSNCS. In this study, a novel magnetic nickel cobalt sulfide/sodium dodecyl benzene sulfonate (FSNCS/SDBS) adsorbent was synthesized successfully by a facile protocol and was developed to remove ciprofloxacin (CIP) for water purification. The FSNCS/SDBS adsorbent is featured with excellent CIP adsorption capacity of 625 mg·g−1 (much higher than reported most adsorbents), wide pH adaptability (little changed CIP adsorption capacity in pH 6–11), and good magnetic property. The effects of pH and ionic strength on CIP adsorption were investigated. The calculative thermodynamic parameters indicated that CIP adsorption by FSNCS/SDBS was spontaneous and exothermic. CIP adsorption followed pseudo-second-order kinetics and an isotherm best fit with the Langmuir adsorption mode. The adsorption mechanism of CIP onto FSNCS/SDBS was proposed and demonstrated, which included the electrostatic interaction, π–π interaction, coordination with metal and hydrogen bonding. [ABSTRACT FROM AUTHOR]

With the rapidly increased discharges of various complex dyeing wastewaters, adsorbents are required to own more properties such as cost-effectiveness, amphoteric ability, and rapid solid-liquid separation ability, to treat dyeing wastewaters. A multi-functional adsorbent was synthesized by co-grafting m-phenylenediamine and sodium allyl sulfonate on the surface of a low-cost base-material: hollow glass microsphere (HGM). Characterization results indicated the surface roughness and –Si–OH groups of HGM were increased by NaOH corrosion; functional groups such as aromatic-rings, –NH 2 , and –HSO 3 − were grafted on the surface of HGM. The synthesized adsorbent showed amphoteric attraction abilities for anionic acid green 25 and cationic basic fuchsin dyes. Kinetics and isotherms studies suggested the PSO model and Langmuir model were most satisfactory for adsorption processes, the theoretical maximum adsorption capacities for acid green 25 and basic fuchsin reached 454.55 and 588.24 mg g−1, respectively. The mechanism investigations indicated the electrostatic attraction, π-π stacking, and hydrogen bonds were the potential interaction forces between dyes and adsorbents. The synthesized material owns self-floating ability due to the hollow structure of HGM, over 95.7% of adsorbents were collected at water surface via the self-floating process in 12 min, which was beneficial to the solid-liquid separation process and the reuse of adsorbents. The technologies developed by these research efforts can serve as templates for synthesizing multi-functional adsorbents for complex wastewaters decontaminations. [Display omitted] • First demonstration of an amphoteric self-floating adsorbent. • The adsorption capacities of anionic/cationic dyes reached 454.55/588.24 mg g−1. • Electrostatic force, π-π stacking, hydrogen bond were dominant adsorption mechanisms. • Over 95.7% of adsorbents were collected at the water surface within 12 min. • The multi-functional adsorbent is beneficial for cleaner production of dyeing goods. [ABSTRACT FROM AUTHOR]

• Multifunctional magnetic composite nanoparticles were facilely prepared. • The as-prepared FS@CS-PAA showed excellent adsorption capacities for cationic dyes. • FS@CS-PAA exhibited satisfactory removal rates for metal ions in a wide pH range. • The good adsorption ability was attributed to abundant active sites from CS-PAA. • FS@CS-PAA's good stability and reusability facilitated its practical application. Wastewater containing highly toxic, non-biodegradable and carcinogenic organic dyes and metal ions has been regarded as a severe threat to ecological environment and human health. Thus, it is of great significance to develop an effective approach to purify this kind of wastewater. Herein, novel magnetic adsorbent FS@CS-PAA was facilely prepared by coating anionic polyacrylamide-modified chitosan (CS-PAA) on the surface of silica-combined Fe 3 O 4 (FS). The morphology, structure, physic-chemical and magnetic properties of as-prepared FS@CS-PAA were fully characterized by various characterization techniques. Its adsorption behaviors towards cationic dyes and metal ions were systematically investigated in single systems, binary systems, and model wastewater. FS@CS-PAA was proved to have superior adsorption capacities of 2330.17 and 1044.06 mg g−1 respectively for crystal violet and methylene blue at 318.15 K, much higher than other reported adsorbents. Besides, FS@CS-PAA exhibited a pH-independent adsorption capability for metal ions, as demonstrated in single systems and in metal ion-dye binary systems, thus it could be used to treat a variety of metal ion wastewaters with different pH values. Moreover, FS@CS-PAA could be effectively and easily regenerated by HCl solution after the treatments of both synthetic wastewater and model wastewater. As revealed in FTIR and XPS analyses, the adsorption mechanism was mainly attributed to the electrostatic interaction, hydrogen bonding, cation exchange and chelating effect. With its excellent adsorption capacity for cationic dyes, pH-independent adsorption capability for metal ions, easy separation ability, satisfactory stability and good reusability, FS@CS-PAA can become an ideal candidate for wastewater treatment. [ABSTRACT FROM AUTHOR]

The novel, highly active, acid resistance and reusable immobilized adsorbent, 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTCA)-decorated chitosan-coated magnetic silica nanoparticle, has been fabricated and applied to the highly selective adsorption of uranium from a multi-ion solution. • Novel PBTCA-decorated chitosan-coated magnetic SiO 2 nanoparticles were fabricated. • A new, highly active, acid resistance, and reusable magnetic sorbent was obtained. • Coexisting ion experiments showed highly selective uranium adsorption. • CoFe 2 O 4 @SiO 2 @CS-PBTCA showed higher acid resistance than uncoated silica adsorbent. • Adsorbent binds to uranium mainly though carboxyl and phosphonic oxygen atoms in PBTCA. The separation and recovery of uranium resources from nuclear waste solutions is important for achieving uranium reuse and environmental protection. In this study, a novel adsorbent, 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTCA)-decorated chitosan-coated magnetic silica nanoparticles, was fabricated and applied to the highly selective adsorption of uranium from aqueous solution. Selective sorption in a multi-ion solution (pH 4.0) containing 14 coexisting cations resulted in CoFe 2 O 4 @SiO 2 @CS-PBTCA showing an excellent uranium adsorption capacity of up to 83.16 mg g−1, which was much higher than that of ungrafted CoFe 2 O 4 @SiO 2 @CS (29.99 mg g−1). The adsorbent also exhibited higher acid resistance than uncoated silica adsorbent under pH 1.0 conditions, with CoFe 2 O 4 @SiO 2 @CS-PBTCA showing barely any iron and cobalt leaching, while CoFe 2 O 4 @CS-PBTCA showed iron and cobalt leaching amounts of 2.97 and 0.93 mg L−1, respectively. The desorption experiment used 0.2 M PBTCA (pH 1.0) as eluent, with the results showing that uranium ions were readily and rapidly desorbed. Furthermore, CoFe 2 O 4 @SiO 2 @CS-PBTCA maintained outstanding stability and adsorption performance after five reuse cycles. The mechanism for U(VI) removal was investigated by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy, with the results suggesting that the adsorbent binds to uranium mainly though oxygen atoms of carboxyl groups and phosphonic groups in PBTCA. This strategy shows strong potential for developing a variety of novel, highly active, acid resistance, and reusable immobilized functional magnetic materials for effective separation of uranium from a multi-ion solution. [ABSTRACT FROM AUTHOR]

Wastewater containing dyes poses a severe threat to human health and to environmental safety. Hence, finding an effective way to treat this wastewater has attracted wide attentions. In this study, quaternary ammonium group-rich magnetic nanoparticles (MNPs), Fe 3 O 4 @SiO 2 -MPS-g-DAC (FSMD), were facilely prepared by grafting polymerization and served as a cationic adsorbent to remove anionic dye Orange G from aqueous solutions. Being compared with Fe 3 O 4 @SiO 2 -MPS MNPs, the adsorption capacity of FSMD MNPs was notably enhanced and it could be maintained in a high level under a wide solution pH range. The dependency on pH and the sensitivity to ionic strength indicated that the main adsorption mechanism was the electrostatic interaction. The adsorption kinetics followed the pseudo-second-order model, and the adsorption isotherms were well described with the Langmuir model. According to the thermodynamic analysis, the adsorption process was spontaneous and endothermic. FSMD MNPs were proved to have advantages of fast adsorption rate, high adsorption capacity, easy separation ability under external magnetic field, and satisfactory reusability, therefore they can be applied in the removal of anionic dyes from wastewater. [ABSTRACT FROM AUTHOR]