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Novel adsorbents, poly([2-(methacryloxy)ethyl]trimethylammonium chloride) modified magnetic chitosan particles (DMCPs), were synthesized via free radical polymerization and applied to adsorb Cr(VI) from aqueous solution. The effects of pH (2–11), Cr(VI) concentration (10–200 mg/L) and contact time (0–420 min) on the adsorption performance were evaluated. The results showed that the adsorption capacity of DMCPs was much larger than that of magnetic chitosan particles (MCPs) in the examined pH range and decreased with Cl − concentration increasing, indicating that electrostatic interaction and ion exchange are the governing mechanisms of Cr(VI) adsorption by DMCPs. The Langmuir isotherm model and pseudo-second-order kinetic model fitted the experimental data well. The maximum adsorption capacity of DMCPs is 153.85 mg/g. Besides, Cr(VI)-loaded DMCPs could be easily separated and efficiently regenerated. Therefore, DMCPs are promising candidates for Cr(VI) adsorption owing to their excellent performance in a wide pH range, easy separation and good reusability. [ABSTRACT FROM AUTHOR]

A novel chitosan-based magnetic adsorbent [poly(2-acrylamido-2-methylpropane sulfonic acid) grafted magnetic chitosan microspheres, PMCMs] was successfully fabricated via free radical polymerization for effectively removing the cationic dye methylene blue (MB). The effects of initial solution pH (1.0–10.0), temperature (30–50 °C), contact time (0–660 min) and initial concentration (50–1600 mg/L) were studied. The results indicated that the adsorption capacity increased with the increasing of initial solution pH and temperature. The adsorption kinetic and adsorption equilibrium data fitted closely to the pseudo-second-order kinetic model and Langmuir isotherm model respectively, confirming monolayer adsorption. The maximum adsorption capacity of PMCMs for MB at initial solution 9.0 were 1000, 1250 and 1428 mg/g at 30, 40 and 50 °C, respectively. Furthermore, the magnetic microspheres could be easily separated using a magnet and effectively regenerated after finishing the treatment process. Therefore, PMCMs are promising candidates for the removal of dye from wastewater. [ABSTRACT FROM AUTHOR]

In this work, a novel chitosan-based magnetic adsorbent [poly(2-(dimethylamino)ethyl methacrylate) grafted magnetic chitosan microspheres, GMCMs] was synthesized by graft polymerization of (2-(dimethylamino)ethyl methacrylate on the surface of magnetic chitosan microspheres (MCMs). The as-prepared GMCMs exhibited significantly enhanced adsorption capacity towards anionic dyes (e.g., Acid Green 25 and Reactive Blue 19) compared with MCMs. It is due to the fact that the abundant tertiary amine groups of the grafted polymer protonated at low pH and the polymer chains stretched as a result of electrostatic repulsions and chain-solvent interactions. The stretched polymer chains provided a variety of adsorption sites, which efficiently adsorbed dyes through electrostatic interactions and hydrogen bonding. While, in alkaline conditions, the tertiary amine groups were deprotonated and the polymer chains collapsed due to hydrophobic interactions, which facilitated the regeneration of the dye-loaded GMCMs at high pH. The regenerated GMCMs showed excellent adsorption performance even after five adsorption–desorption cycles. Besides, the GMCMs could be rapidly separated from aqueous solutions under an external magnetic field. Therefore, the GMCMs materials bear great application potentials in water treatment owing to its high adsorption capacity, pH-responsiveness, facile regeneration and good reusability. [ABSTRACT FROM AUTHOR]

Simultaneously removing heavy metal and dye from complex wastewater is of great significance to industrial wastewater treatment. Herein, a novel magnetic adsorbent, DTPA-modified chitosan-coated magnetic silica nanoparticle (FFO@Sil@Chi-DTPA), was successfully prepared and used to enhance the Pb(II) selective adsorption from multi-metal wastewater based on anion-synergism. In the competitive experiment conducted in a multi-ion solution, the type of selective adsorption of metals was changed by the adsorbents before and after amidation, in which FFO@Sil@Chi-DTPA exhibited an excellent selectively for capturing Pb(II), while FFO@Sil@Chi demonstrated highly selective adsorption of silver. More importantly, the selective adsorption of Pb(II)S by FFO@Sil@Chi-DTPA was enhanced from 111.71 to 268.01 mg g−1 when the coexisting MB concentrations ranged from 0 to 100 mg L−1 at pH 6.0. In the Pb(II)-MB binary system, Pb(II) and MB exhibited a synergistic effect, in which the presence of MB strengthened the adsorption effect of Pb(II) due to the sulfonic acid groups in MB molecules that create new specific sites for Pb(II) adsorption, while MB adsorption was also enhanced by the presence of Pb(II). This work provides a new strategy for exploring novel adsorbents that can enhance the selective removal of heavy metal in complex wastewater based on anion-synergism. [Display omitted] • A novel DTPA-modified chitosan-coated magnetic silica nanoparticle was prepared. • FFO@Sil@Chi-DTPA exhibited higher acid resistance than uncoated silica adsorbent. • FFO@Sil@Chi-DTPA showed high selectivity in capturing lead from multi-ion solutions. • Coexisting MB enhanced the selective adsorption of Pb(II) in complex wastewater. • Possible adsorption mechanisms in both single and binary systems were proposed. [ABSTRACT FROM AUTHOR]

[Display omitted] • The magnetic nanoadsorbent with specific core-shell structure was synthesized. • Fe 3 O 4 @Carbon@ZIF-8 showed excellent adsorption capacities for Congo red and Cu(II). • The good adsorption ability was attributed to abundant active sites from ZIF-8. • Fe 3 O 4 @Carbon@ZIF-8 can selectively remove CR and Cu(II) from complex wastewater. • Nanoadsorbent's good stability and reusability indicated its practical application. Efficient and convenient removal of organic dyes and heavy metals from complex wastewater is still a challenge for human health and ecosystem remediation. Novel adsorbent, Fe 3 O 4 @Carbon@ZIF-8 with specific core-shell structure was synthesized by layer-by-layer self-assembly. The hydrophilic carbonaceous shell acts as both a linker and stabilizer between Fe 3 O 4 and ZIF-8. The characteristics of self-made adsorbent were comprehensively identified by numerous characterization methods. The adsorption kinetics, isotherms and the influence of various reacting parameters on its adsorption capacity of Congo red (CR) and Cu(II) were systematically investigated. Compared with other reported adsorbents, the maximum adsorption capacities of Fe 3 O 4 @Carbon@ZIF-8 towards CR (806.45 mg g−1) and Cu(II) (234.74 mg g−1) were much higher. Moreover, the adsorption process followed pseudo-second-order kinetics and Langmuir isotherm models. Selective adsorption of CR was investigated in the presence of cationic and anionic dyes, and the same as Cu(II) in the existence of competitive ions, which revealed that it was appropriate for selective adsorption toward CR and Cu(II) in complex wastewater. On the basis of FT-IR and XPS analyses, electrostatic interaction, hydrogen bonding, π-π bonding and ion exchange were involved in the mechanism of adsorption. Fe 3 O 4 @Carbon@ZIF-8 is suitable for practical application because of its good stability and reusability. [ABSTRACT FROM AUTHOR]

Magnetic separation technology is an efficient and feasible way to achieve rapid recovery of adsorbents, thus, the use of magnetic adsorbents has attracted the attention of many researchers. However, currently reported magnetic adsorbents have limited adsorption capacity due to insufficient adsorption sites and reactive groups. In this work, a novel magnetic chitosan-based amphiphilic adsorbent (PFSC) was synthesized by using UV-light irradiation method to combine with acryloyloxyethyl dimethylbenzyl ammonium chloride (AO), a molecule containing benzyl groups. PFSC and its precursors were carefully characterized, and their adsorption performances for the removal of anionic dyes were explored. The characterization results showed that the magnetic copolymers with a type of microsphere structure were successfully synthesized. Moreover, PFSC exhibited superior adsorption efficiency and pH resistance compared to those of an unmodified chitosan-based magnetic adsorbent (FSC). The maximum adsorption capacities of PFSC towards orange II (OG), acid red 88 (AE) and red amaranth (RM) were 955.0, 1075.8 and 567.5 mg/g at pH 3.0, respectively. The adsorption kinetics and isotherms of PFSC were consistent with that of a pseudo-second order kinetic model and the Langmuir isotherm model. In addition, adsorption-desorption experiments showed that PFSC could be rapidly separated and efficiently recycled even after 4 uses. More importantly, the FTIR and XPS results revealed that electrostatic adsorption and π-π stacking interactions were the main adsorption mechanisms for the PFSC-enhanced removal of anionic dyes. [Display omitted] • The chitosan-based amphiphilic magnetic copolymer was successfully synthesized by the UV-light initiated method. • The novel magnetic copolymer can be easily separated from solution by magnetic force. • The enhanced electrostatic adsorption and π-π stacking effect played an important role in the removal of anionic dyes. • The novel magnetic copolymer can be reused by simple acid-alkali adjustment. [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]

• Self-floating adsorbents can reach surface solid-liquid separation spontaneously. • The two-step synthesis process of SFA is simple and efficient. • Single-layer grafting allows the adsorption to reach equilibrium within 10 min. • Concentrate low concentration dyes to industrially usable levels by desorb method. In the case of a sharp increase in the price of dyes, the dyes concentration of in wastewater is important for environmental protection and industrial costs reduction. In this study, we grafted single-layer amino groups onto the surface of the hollow glass microspheres by a two-step simple synthesis, and the anionic dyes adsorption process reaches equilibrium within 10 min. The as-synthesized adsorbent has self-floating ability to achieve high-efficiency surface solid-liquid separation with water. SEM, EDS, S BET , FT-IR, XPS, TGA characterizations results demonstrated the successful grafting of amino groups and the important role of the pretreatment process in the two-step synthesis. The results of adsorption isotherms and kinetics show the adsorption process belongs to single-layer adsorption with equal adsorption sites, and the adsorption capacities for acid orange 7 and amaranth reach 428.99 mg g−1 and 145.62 mg g−1, respectively. Regeneration of the adsorbent and concentration of the dye solutions can be achieved by dispersing the separated adsorbent in alkaline solution, the maximum concentrated concentration of acid orange 7 and amaranth was 6321.57 mg L−1 and 2431.84 mg L−1, respectively. This study provides new insights for the solid-liquid separation of water treatment agents and the resource regenerating of dyeing wastewater. [ABSTRACT FROM AUTHOR]

• Magnetic biosorbents (PMCCs) were designed and fabricated by radical polymerization. • PMCCs had specific morphological and molecular structure for ciprofloxacin removal. • PMCCs exhibited excellent adsorption capacity of 527.93 mg·g−1 for ciprofloxacin. • The adsorption mechanisms of ciprofloxacin by PMCCs were systematically elucidated. • PMCCs displayed rapid separation and favorable reusability. Magnetic biosorbents with specific morphological and molecular structure (PMCCs) were designed for the removal of ciprofloxacin (CIP) from water. Radical polymerization method was applied to immobilize the designed polymer brushes onto core-shell shaped magnetic microspheres to fabricate PMCCs. PMCCs exhibited a maximum adsorption capacity of 527.93 mg·g−1, which is much higher than reported adsorbents, owing to the complete stretch of polymer brushes and increased active sites as well as enhanced interaction. The investigation on the adsorption behavior of PMCCs for CIP manifested that CIP adsorption well fitted the Langmuir isotherm model and pseudo-second-order kinetic model. The calculated thermodynamic parameters suggested that CIP adsorption onto PMCCs was spontaneous and exothermic. Further recycling experiments showed a loss of less than 20% in the CIP adsorption capacity after five times, demonstrating the reusability of the as-designed biosorbents. [ABSTRACT FROM AUTHOR]

• A novel surface-decorated magnetic chitosan biopolymer (VMCP) was fabricated. • VMCP exhibited significantly improved removal performance toward Cr(VI). • Simultaneous adsorption and reduction of VMCP for Cr(VI) was investigated. • The mechanisms of Cr(VI) removal by VMCP were elucidated. Poly(4-vinyl pyridine) decorated magnetic chitosan biopolymer (VMCP), as an absorbent and reductant, was prepared and used to remove hexavalent chromium (Cr(VI)) from aqueous solution. Compared with undecorated magnetic biopolymer, VMCP exhibited significantly improved removal performance under identical experimental conditions. The kinetics, isotherms, and thermodynamics of Cr(VI) adsorption onto VMCP were investigated. Results demonstrated that the maximum monolayer adsorption capacity of VMCP was 344.83 mg/g, which was considerably higher than most reported adsorbents. The mechanism for Cr(VI) removal was explored based on XPS and FTIR analyses. The main mechanisms were concluded to be Cr(VI) adsorption onto the positively charged VMCP surface and the reduction of Cr(VI) to Cr(III), followed by coordination between Cr(III) and N atoms. The easy regeneration, satisfactory reusability, and remarkable performance in column tests revealed the high potential of VMCP in treating Cr(VI)-contaminated water. [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]

[Display omitted] • PVA/PSSNa semi-IPN@Ni foam removes 95.17% CIP and 99.20% Ni(II) from wastewater. • Satisfactory adsorption occurs under neutral to slightly acidic pH (3–7). • In the binary system, Ni(II) greatly affects CIP adsorption, while CIP slightly affects Ni(II). • The interactive term of Ni(II) concentration and pH notably affects the CIP removal. • Removal of CIP and Ni(II) is most affected by their own concentration and pH. The coexistence of antibiotics and heavy metals in wastewater notably influences their adsorption removal behavior. However, the synergistic and antagonistic characteristics and mechanisms of their co-adsorption remain unclear. A novel adsorbent, PVA/PSSNa semi-IPN@Ni foam, was synthesized and applied to study its features and mechanisms in the single and binary systems of ciprofloxacin (CIP) and Ni(II). Exceptional removal efficiencies of 95.17 % for CIP and 99.20 % for Ni(II) were achieved. The interactive effects between CIP and Ni(II) were comprehensively explored through adsorption capacity ratio (Rq) and response surface methodology. Mechanistic insights were obtained through NaCl charge shielding experiments, substructure analog molecule probes experiments, theory calculations, as well as FTIR and XPS characterizations. The outcomes suggest that in the single system of CIP, the adsorption mechanisms include electrostatic attraction, hydrogen bonding, and π-π interactions. In the single system of Ni(II), mechanisms include electrostatic attraction and coordination. In the binary system of CIP + Ni(II), low Ni(II) concentrations facilitate CIP adsorption through coordination and bridging, whereas high Ni(II) concentrations let to competition for adsorption sites. Interestingly, the presence of CIP had minimal impact on Ni(II), exhibiting only a slight synergistic effect. These findings highlight the PVA/PSSNa semi-IPN@Ni foam as a hopeful candidate for removing CIP and Ni(II) from wastewater, and contribute to a deeper comprehension of synergistic and antagonistic mechanisms in the binary system involving CIP and Ni(II). [ABSTRACT FROM AUTHOR]

Owing to the lower toxicity and mobility of inorganic As(V), the oxidative removal of As(III) is deemed as the optimal approach for arsenic elimination from water. Herein, a synthetic TiO 2 -supported CuO material (Cu-TiO 2) was coupled with sulfite (S(IV)) to remove As(III) at neutral pH. The combined process coupled oxidation with adsorption (i.e., As(III) removal by Cu-TiO 2 /S(IV)) was superior than a divided preoxidation-adsorption process (i.e., As(V) removal by Cu-TiO 2) for arsenic removal. Attractively, low concentration of As(III) (50−300 μg L−1) could be completely removed by Cu-TiO 2 (0.25 g L−1)/S(IV) (0.5 mM) within 60 min. Mechanism investigations revealed that the efficient As(III) removal was attributed to the continuous oxysulfur radicals (SO x •−) oxidation and Cu-TiO 2 adsorption. The surface-adsorbed and free sulfate radicals (SO 4 •−) were further identified as the crucial oxidizing species. The Cu-TiO 2 played the dual roles as a catalyst for S(IV) activation and an absorbent for arsenic immobility. The influence of operating parameters (i.e., As(III) concentration and sulfite dosage) and water chemistry (i.e., pH, inorganic anions, dissolved organic matters, and temperature) on As(III) removal were systematically investigated and optimized. Overall, the proposed process has potential application prospects in rehabilitating the As(III)-polluted water environment using industrial waste sulfite. [Display omitted] • As(III) removal was achieved in an integration of oxidation and adsorption. • Free and surface-adsorbed SO 4 •− were responsible for As(III) oxidation. • Sulfite drove As(III,V) forming more monodentate complexes on catalyst surface. • Possible synergy mechanism of Cu-TiO 2 /sulfite system was proposed. • The operation factors were investigated and optimized systematically. [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]

Environmentally friendly magnetic sodium alginate beads with glutaraldehyde cross-linking catalyzed by acetic acid-hydrochloric acid were successfully designed (FSSi@SA), and the magnetic bio-sorbents after amide reaction (FSSi@SA-sula) were utilized to absorb fluoroquinolone antibiotics in water. After amidation, FSSi@SA-sula exhibited strong pH adaptability (pH = 6.0–12.0). Langmuir and pseudo-first-order models can better describe the isotherm and kinetic process well, respectively. Under the optimization conditions with pH = 7 and temperature of 318.15 K, the maximum adsorption capacities of FSSi@SA-sula on the third-generation FQs ciprofloxacin (CIP) and the fourth-generation FQs moxifloxacin (MOX) respectively reached 365.66 and 149.57 mg g−1. The thermodynamics research indicated that the as-prepared FSSi@SA-sula is spontaneous and feasible. And after five adsorption cycles, the loss of adsorption capacity was less than 20% for both CIP and MOX, demonstrating the fine reusability and stability of the designed magnetic bio-sorbent. This study provides some ideas for facile synthesis of acid-catalyzed sodium alginate-glutaraldehyde cross-linking, which has promising applications in grafting various types of groups onto the retained carboxyl groups of sodium alginate spheres for the various contaminants removal in wastewater. [Display omitted] • FSSi@SA-sula beads were prepared by acid-catalyzed glutaraldehyde cross-linking. • FSSi@SA-sula showed excellent adsorption and reusability for CIP and MOX. • Langmuir and pseudo-first-order models better fitted adsorption process. • The mechanisms include electrostatic interactions, hydrogen bonding and n-π EDA. • Provided new ideas for facile synthesis of functional sodium alginate adsorbents. [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]

[Display omitted] • Magnetic alginate-based biosorbents are prepared by free radical polymerization. • FSSEB-20 shows excellent adsorption capacities for DS and X-3B, respectively. • FSSEB-20 still shows satisfactory recycling rate after five runs. • The mechanism includes electrostatic action, hydrogen bonding and π-π interaction. In this work, we unveiled a novel magnetic biosorbent, poly (Benzyldimethyl[2-[(2-methyl-1-oxoally) oxy] ethyl] ammonium chloride)-immobilized magnetic sodium alginate composite-20 (FSSEB-20), and studied its adsorption behavior for two groups of toxic anionic organic pollutants, DS and X-3B from simulation wastewater. Results demonstrated that the Langmuir model could well describe the adsorption behavior of DS and X-3B on FSSEB-20, the maximum adsorption capacity of FSSEB-20 towards DS and X-3B are 340.58 mg g−1 and 370.85 mg g−1, respectively; according to kinetic results, the adsorption processes of both DS and X-3B on FSSEB-20 followed the pseudo-second-order kinetic model. To test the reusability of FSSEB-20, five runs of regeneration tests were performed. The removal rates of FSSEB-20 towards DS and X-3B are more than 74%. In addition to these, the surface interactions between FSSEB-20 and DS/X-3B were systematically analyzed based on the characterization results of FT-IR and XPS, which provided significant insights into the interactions between biosorbents and pollutants in wastewater. The mechanism of DS and X-3B adsorption by FSSEB-20 includes electrostatic interaction, hydrogen bonding and π-π interaction. Furthermore, this study also provides a new enlightenment for expanding the treatment of pollutants in wastewater with sodium alginate-based magnetic biosorbent. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel floating-separation adsorbent (APHGS-g-P(AMPS)) was designed and synthesized. • APHGS-g-P(AMPS) showed outstanding self-floating separation ability. • APHGS-g-P(AMPS) with satisfactory adsorption capacity was rich in –OH, –NH 2 and -SO 3 -. • The electrophilic addition strategy facilitated the grafting of P(AMPS) polymerized chains. • The sulfonic acid group exhibited excellent universal adsorption for MB and Pb(II). Inferior solid–liquid separation behavior and inadequate adsorption capacity are the main bottlenecks of current wastewater treatment adsorbents, especially in the purification of wastewater containing dyes and heavy metals. Accordingly, a novel floating separation adsorbent with polymeric chain structure, hollow glass sphere-g-(3-aminopropyl) triethoxysilane-g-poly(2-acrylamide-2-methyl-1-propanesulfonic acid) (APHGS-g-P(AMPS)), was fabricated through an electrophilic addition post-grafting strategy. The obtained APHGS-g-P(AMPS) exhibited satisfactory adsorption for methylene blue (MB) and lead ion (Pb(II)), as well as efficient flotation. Adsorption behavior analysis showed that the Pseudo-second-order kinetic model and Langmuir isotherm model were suitable for describing the adsorption process, and the maximum adsorption capacities for MB and Pb(II) were 249.33 and 345.93 mg·g−1 (313.15 K), respectively. Analysis of the adsorption mechanism indicated that the sulfonic acid group exhibited excellent universal adsorption for MB and Pb(II), which played a crucial role in the adsorption process. Furthermore, the efficient grafting of P(AMPS) polymerized chains onto the adsorbent was the pivotal factor to enhance adsorption. This study provided an efficient electrophilic addition post-grafting strategy for the structural design and functional modification of floating separation adsorbents. The results of this study are expected to have positive implications for the efficient purification of dyes and heavy metals wastewater. [ABSTRACT FROM AUTHOR]

[Display omitted] • A hollow self-floating adsorbent was specially designed and prepared. • HGM was decorated with dopamine and taurine to enhance adsorption properties. • HGM@PDA-SO 3 H exhibited satisfactory reusability and resistance to ion interference. • TC was efficiently removed over a wide pH range. • The hollow structure endowed HGM@PDA-SO 3 H with self-floating separation capability. Hollow glass microspheres (HGM), as a promising hollow spherical ultra-light material, have the advantages of uniform particle size, regular shape, high mechanical strength and stable physical and chemical properties. It has been widely utilized in many fields but its application in water treatment is yet to be developed. Herein, a novel self-floating composite adsorbent was obtained by forming a poly(dopamine) (PDA) biomass coating on the surface of HGM and introducing sulfonic acid groups. The hollow composite material (HGM@PDA-SO 3 H) was utilized in the adsorptive elimination of tetracycline (TC) from aqueous solutions. In addition to great adsorption performance, HGM@PDA-SO 3 H also exhibited satisfactory self-floating solid-liquid separation capability. Langmuir, pseudo second-order and Elovich models correlate isotherms and kinetic data relatively well, respectively. The theoretical saturated TC adsorption amount of HGM@PDA-SO 3 H evaluated by Langmuir model reached 333.70 mg g−1. Thermodynamic analysis confirmed the spontaneous exothermic property of the adsorption process. There was no serious decline in the adsorption of TC by the material after 5 adsorption cycles, and the adsorbent saturated with contaminants could be easily regenerated via solution desorption, reflecting its satisfactory renewability and stability. Based on the results of batch experiments and characterization analysis, it could be concluded that the corresponding adsorption mechanisms mainly involve electrostatic attraction, hydrogen bonding and π-π stacking interactions. This research aimed to decorate HGM with biomaterials and apply it in the adsorptive purification of TC-contaminated water, which brought some insights and inspiration for the environmental application of HGM, and proved its potential applicability. [ABSTRACT FROM AUTHOR]

[Display omitted] • Self-floating cyclodextrin-modified polymer was prepared. • The adsorption performance of TFCD and FTFCD was compared. • FTFCD simplified the recycling process by wrapping a hollow glass microsphere. • Porous structure and hydrophobic cavity favor the dye adsorption. • Polymers exhibited excellent selectivity toward cationic dyes. The separation and recycling processes of current cyclodextrin (CD)-based adsorbents are complicated. Thus, a novel composite based on a large surface area, porous, and self-floating tetrafluoroterephthalonitrile (TFN)-crosslinked CD polymer (FTFCD), was fabricated, characterized and applied to treat cationic dye pollutants. The characterization showed a porosity, good thermal stability, a stable crystal structure, and abundant functional groups on the prepared FTFCD, which had demonstrated great improvement on its adsorption capacity towards attention grabbing pollutants. The removal efficiency of the adsorbents for malachite green (MG) remained above 95% at pH 1 ∼ 10. In addition, the adsorbents were found to rapidly reach equilibrium governed by the pseudo-second-order kinetic model, and the maximum adsorption capacity of FTFCD was 1390.263 mg/g, as corroborated by the Langmuir isotherm model. While the phenolate groups of FTFCD found to electrostatically interacts with the MG strong cationic quaternary amine group, hydrogen-bonding was responsible for the hydroxyl group of FTFCD and the quaternary amine group binding. Meanwhile, the triangular cone configuration of MG makes it easy to be entrapped and absorbed in the hydrophobic cavity. Besides, after regeneration of exhausted FTFCD for five successive cycles, the MG removal efficiency still reached more than 80%. Thus, FTFCD could be applied as a potential alternative adsorbent for cationic dye removal owing to its excellent adsorption performance, convenient recycling, wide pH application, and environmental friendliness. [ABSTRACT FROM AUTHOR]

The selective separation and recovery of valuable metals from complex polluted wastewater is of great significance to the protection of water resources and the realization of resource recycling. Herein, the chitosan-coated magnetic silica core-shell nanoparticles (FO@SD@CS) were fabricated and applied as adsorbents for highly selective removal of precious metals silver ions (Ag(I)) from complex wastewater. In multi-ion compound polluted solutions, FO@SD@CS showed excellent selective adsorption of Ag(I) in a wide pH range, and an enhancement of the highly selective adsorption capacity of Ag(I), which was increased from 85.86 to 126.74 mg g−1 when the concentrations of methyl blue (MB) coexisted in the solution from 0 to 40 mg L−1 at pH 6.0. The results of Ag(I) single system batch adsorption experiments illustrated that the adsorption behavior of FO@SD@CS to Ag(I) shows obvious pH responsiveness, the adsorption capacity of Ag(I) increases with the increasing of pH value. The results of the adsorption isotherm and kinetics demonstrated that Langmuir and pseudo-second-order kinetics can better describe the adsorption behavior of Ag(I) on FO@SD@CS, indicating that the adsorption process was controlled by chemisorption and the maximum monolayer adsorption capacity reached 116.28 mg g−1 at room temperature. Additionally, in the dye-metal binary system, the coexisting MB promoted the adsorption capacity of FO@SD@CS to Ag(I) from 116.28 to 156.25 mg g−1, showing a synergistic adsorption effect. This study shows that the enhanced selective separation and recovery of metal ions from wastewater based on anion-synergistic not only provides new ideas for wastewater treatment, but also has important significance for water resources reuse. [Display omitted] • A magnetic adsorbent with core-shell structure was successfully prepared. • FO@SD@CS exhibited higher acid resistance than uncoated silica adsorbent. • FO@SD@CS showed high selectivity in capturing silver from multi-ion solutions. • Coexisting MB enhanced the selective adsorption of Ag(I) in complex wastewater. • Possible adsorption mechanisms in both single and binary systems were proposed. [ABSTRACT FROM AUTHOR]

The ubiquitous present antibiotics in aquatic environment is attracting increasing concern due to the dual problems of bioaccumulation toxicity and antibiotic resistance. In this study, a low-cost chitin-biocalcium (CC) composite was developed by a facile alkali activation process from shell waste for typical antibiotics ciprofloxacin (CIP) removal. Response surface methodology (RSM) was utilized to optimize synthesis methodology. The optimized CC products featured superior CIP removal capacity of 2432 mg/g at 25 °C (adsorption combined with flocculation), rapid adsorption kinetics, high removal efficiency (95.58%) and wide pH adaptability (under pH range 4.0–10.0). The functional groups in chitin and high content of biocalcium (Ca2+) endowed CC abundant active sites. The kinetic experimental data was fitted well by pseudo-second-order and intraparticle diffusion model at different concentrations, revealing the removal was controlled by chemisorption and mass transport step. From the macroscopic aspect, flocs were produced with the increase of CIP concentration during the reaction, adsorption combined with flocculation were related to the CIP removal. From the microcosmic aspect, the superior removal performance was attributed to cation bridging, cation complexation among biocalcium-CIP and hydrogen bond between functional groups of chitin and CIP. [Display omitted] • Chitin-biocalcium was derivate from cheap and abundant natural shell waste. • Adsorption and flocculation were involved in the CIP removal. • Chitin-biocalcium showed wide pH adaptability for CIP removal. • Chitin-biocalcium possessed amazing removal capacity toward CIP (2432 mg/g). • Functional groups in chitin and Ca2+ were related to CIP removal. [ABSTRACT FROM AUTHOR]

• A magnetically separable amphoteric biosorbent (PD-Fe 3 O 4 @CCS) was fabricated. • The PD-Fe 3 O 4 @CCS displayed effective adsorption performance for Cr(VI) and Cu(II). • Adsorption behaviors of Cr(VI) and Cu(II) in single and binary systems were studied. • Ion exchange, electrostatic and coordination (chelation) interactions are involved in Cr(VI) (Cu(II)) adsorption. Here we unveiled a novel magnetically separable amphoteric biosorbent (PD-Fe 3 O 4 @CCS) and investigated its adsorption behavior toward two classes of heavy metals, hexavalent chromium (Cr(VI)) and copper (Cu(II)) ions from water. Results indicated that the adsorption behavior of PD-Fe 3 O 4 @CCS for Cr(VI) was well described by Langmuir model; while for Cu(II) adsorption, the Freundlich model was the better one. Based on the kinetic results, both Cr(VI) and Cu(II) adsorption on PD-Fe 3 O 4 @CCS fitted well with the pseudo-second-order kinetic model. To evaluate the reusability and stability of PD-Fe 3 O 4 @CCS, regeneration tests were carried out for five cycles. Furthermore, the applicable feasibility of PD-Fe 3 O 4 @CCS in the real water matrix (including the single and binary pollutant systems) was studied, and results suggested the promising potential of PD-Fe 3 O 4 @CCS for large-scale application. Apart from these, the surface interactions between PD-Fe 3 O 4 @CCS and heavy metal ions in single and binary systems were systematically investigated based on FTIR and XPS analyses, which provided an essential implication for comprehending the interactions between biosorbents and contaminants in wastewater. [ABSTRACT FROM AUTHOR]

• Grafting copolymerization occurred at the amino group of MBF was confirmed. • PSA and MBF-g-P(AM-DAC) played different roles in treatment of dyeing wastewater. • MBF-g-P(AM-DAC) improved settlement efficiency for bridging and adsorption. • Flocs possessed surface area of 24.8201 m2/g and adsorption capacity of 140 mg/g. Congo red (CR) is a typical and widely used azo dye in industries. It possesses the serious threat to ecosystem and public for its indiscriminate discharge. Microbial flocculant (MBF) with various functional groups is a potential flocculant applied in dyeing wastewater treatment, and it has the advantages of high treatment efficiency, biodegradability and non-toxicity. In this study, the functional groups, amino group, ammonium group and acyloxy group, were grafted onto MBF to further improve its thermal stability, solubility and performance. Grafting copolymerization occurred at the amino group of MBF was confirmed by XPS. Polyaluminum silicate (PSA) and self-prepared functional microbial flocculant, MBF-g-P(AM-DAC), played different roles in CR wastewater treatment. PSA contributed to charge neutralization, but its yielded flocs were small. On the contrary, MBF-g-P(AM-DAC) possessed weak charge neutralization but big flocs. Its settlement efficiency has significantly improved. The unsaturated active sites on MBF-g-P(AM-DAC) and its flocs contributed to the adsorption of CR in terms of high surface area and adsorption capacity of the flocs. Physical adsorption and chemical adsorption were both discovered in the treatment. [ABSTRACT FROM AUTHOR]