Effects of co-modified biochar immobilized laccase on remediation and bacterial community of PAHs-contaminated soil

Considering the stability and economy of immobilized enzymes, this study prepared co-modified biochar immobilized laccase product named Fe₃O₄@NaBC@GA@LC via orthogonal experimental design and explored its possibility of remediating polycyclic aromatic hydrocarbons (PAHs) contaminated soil in steel plants. Compared with the free laccase treatment, the relative activity of Fe₃O₄@NaBC@GA@LC remained 60 % after 50 days of incubation at room temperature. The relative activity of Fe₃O₄@NaBC@GA@LC could still retain nearly 80 % after five reuses. In the process of simulating the PAHs-contaminated site treatment experiment in Hangzhou Iron and steel plant, immobilized laccase exhibited efficient adsorption and degradation performances and even the removal rate of 5-ring PAHs reached more than 90 % in 40 days, resulting in improving urease activity and dehydrogenase in the soil and promoted the growth of a PAH degrading bacteria (Massilia). Our results further explained the efficient degradation effects of Fe₃O₄@NaBC@GA@LC on PAHs, which make it a promising candidate for PAHs-contaminated soil remediation.

Preparation and Application of Graphene–Based Materials for Heavy Metal Removal in Tobacco Industry: A Review

Heavy metals are nondegradable in the natural environment and harmful to the ecological system and human beings, causing an increased environmental pollution problem. It is required to remove heavy metals from wastewater urgently. Up until now, various methods have been involved in the heavy metal removals, such as chemical precipitation, chemical reduction, electrochemical, membrane separation, ion exchange, biological, and adsorption methods. Among them, adsorption by graphene–based materials has attracted much more attentions for the removal of heavy metals from wastewater systems in recent years, arising due to their large specific surface area, high adsorption capacity, high removal efficiency, and good recyclability. Therefore, it is quite important to review the heavy metal removal with the graphene–based material. In this review, we have summarized the physicochemical property and preparation methods of graphene and their adsorption property to heavy metals. The influencing parameters for the removal of heavy metals by graphene–based materials have been discussed. In addition, the modification of graphene–based materials to enhance their adsorption capability for heavy metal removal is also reviewed. The heavy metal removal by modified graphene–based materials in the tobacco industry has been especially described in detail. Finally, the future trend for graphene–based materials in the field of heavy metal wastewater treatment is proposed. This knowledge will have great impacts on the field and facilitate the researchers to seek the new functionalization method for graphene–based materials with high adsorption capacity to heavy metals in the tobacco industry in the future.

Reversible Addition?Fragmentation Chain-Transfer Polymerization of Amphiphilic Polycarboxybetaines and Their Molecular Interactions

In this work, we report the first molecular weight-controlled amphiphilic polybetaine synthesis using various hydrocarbons via reversible addition?fragmentation chain-transfer (RAFT) polymerization. The experimental separation of the alkyl aminocrotonate tautomers, which has been the subject of debate, was completed for the first time. The enamine form of these tautomers was further used as a monomer for the RAFT polymerization of amphiphilic polycarboxybetaines. Self-assembly of the amphiphilic polycarboxybetaines showed micelle structures from spherical, rod-like to fractal in the aqueous media due to the competition between both electrostatic and hydrophobic forces. Hydrophobically dominant interactions among amphiphilic polycarboxybetaines and long-chain hydrocarbon alkane molecules were investigated to understand long-chain hydrocarbon alkane crystallization using alkane crystal deposition and viscosity experiments. Strong hydrophobic forces between poly(hexadecyl-grafted aminocrotonate?methacrylic acid) and long-chain hydrocarbon alkane molecules changed the surface properties of the long-chain hydrocarbon alkane nucleus and inhibited the growth of paraffin crystals.

Self-assembled three-dimensional double network graphene oxide/polyacrylic acid hybrid aerogel for removal of Cu2+ from aqueous solution

Three-dimensional (3D) double network graphene oxide/polyacrylic acid (GO/PAA) hybrid aerogels were fabricated under mild conditions from the mixture of GO and acrylic acid (AA) monomers using a one-pot in situ solution polymerization process which included the polymerization of AA and the self-assembly of functional GO sheets. The PAA chains served as not only binder to assemble GO sheets into 3D framework but also modifier to provide more active functional groups. The adsorbents based on such material exhibited superior adsorption performance towards Cu²⁺ ions in aqueous media due to rich mesopores, high specific surface area, and abundant active sites. This work brings a new vision for assembling 3D porous graphene-based nanomaterials as adsorbents in environmental protection.

Simultaneous functionalization and magnetization of biochar via NH3 ambiance pyrolysis for efficient removal of Cr (VI)

Enhancing biochar adsorption capabilities and recollection ability is essential for efficient biochar application. In this study, Nitrogen-doped magnetic biochar was prepared via one-step heating of FeCl₃-laden agar biomass under NH₃ environment. Synthesized magnetic biochar ABF-N₈₀₀ shows a maximum Cr (VI) adsorption capacity up to 142.86 mg g^-1, outperforming that of magnetic biochar and many other previously reported materials. Moreover, a significant increase of magnetic properties obtained by NH₃ ambiance pyrolysis enables easy separation of the adsorbent from the solution after treated with Cr (VI). The physiochemical properties of composites characterized by SEM, EDS, XRD, XPS, VSM, BET surface and pore, Elemental content, and FTIR analysis. The NH₃ ambiance pyrolysis confirmed as an efficient process for surface modification, increased magnetic properties and activated N-functional groups. The Langmuir isotherm model and pseudo-second-order model are applicable for describing adsorption behavior. The thermodynamic study shows that the adsorption was spontaneous and endothermic. The present results warrant the application of simultaneous functionalized and magnetized biochar for Cr (VI) contaminated wastewater treatment.

Enhanced Cr(VI) removal from acidic solutions using biochar modified by Fe3O4@SiO2-NH2 particles

Fe₃O₄@SiO₂-NH₂ magnetic particles with core-shell structure were attached on carboxylated biochar derived from phoenix tree leaves to synthesize a novel magnetic biochar for removing Cr(VI) ions from acidic solutions. FSEM, FTEM, XRD characterizations of the synthesized magnetic biochar revealed that the Fe₃O₄@SiO₂-NH₂ magnetic particles distributed uniformly on the surface or macrospores of carboxylated biochar by strong chemical bonding. The Cr(VI) ions adsorption capacity of magnetic biochar was 27.2mg·g^-1, surpassing original carboxylated biochar (18.2mg·g^-1). VSM and XPS characterizations demonstrated that the attached Fe₃O₄@SiO₂-NH₂ magnetic particles not only endowed biochar with perfect magnetic property (23emu·g^-1) but also provided complexing sites for binding Cr(III) cations reduced from Cr(VI) anions. The Cr(VI) ions removal by magnetic biochar contained three steps: (1) adsorption of Cr(VI) anions by protonated functional groups; (2) reduction of Cr(VI) anions to Cr(III) cations by electron-donor groups; and (3) chelation of Cr(III) cations by amine groups. The adsorption recycling test showed that magnetic biochar kept 85% of its initial Cr(VI) adsorption capacity at the sixth cycle, and the Fe leakage under pH1.0 was smaller than 0.25mg·L^-1. The results indicated that this novel magnetic biochar was applicable for the practical treatment of Cr(VI)-containing wastewater.

Preparation and application synthesis of magnetic nanocomposite using waste toner for the removal of Cr(vi)

In this study, a novel magnetic nanocomposite was prepared using waste toner (WT) through high temperature decomposition, and calcination was conducted in different atmospheres (air, ammonia, and vacuum). WT calcined in ammonia (WT(NH₃)), and it was then utilized as an efficient absorbent for the reduction of Cr(vi) in aqueous solutions; a batch experiment with different conditions was performed to investigate its Cr(vi) removal ability. The effects of two pH-regulating acid (HCl and H₂SO₄) treatments were also studied. It was found that WT(NH₃) could remove about 99% Cr(vi) at pH 2 under H₂SO₄ treatment. The XRD and TEM results coupled with VSM results confirmed that WT(NH₃) is an Fe₃O₄/Fe₂N nanohybrid, which possesses excellent water-dispersibility and remarkable magnetic properties. XPS analysis showed the presence of Cr(vi) and Cr(iii) on the surface of WT(NH₃), which indicated that Cr(vi) was reduced to Cr(iii). Furthermore, H₂SO₄ regulation also promoted the reduction of Cr(vi) by WT(NH₃), and this reduction was higher than that obtained by HCl regulation.

A novel magnetic nanocomposite is prepared using waste toner via calcination in ammonia, which exhibits excellent magnetic properties and high efficiency for the removal of Cr(vi) via pH regulation using H₂SO₄.

Hydrothermal synthesis of hydrocalumite assisted biopolymeric hybrid composites for efficient Cr(vi) removal from water

Hydrocalumite (HC) incorporated biopolymer (alginate and chitosan) based hybrid composite materials were developed for the selective removal of chromium.

3D hierarchical flower-like nickel ferrite/manganese dioxide toward lead (II) removal from aqueous water

A functionalized magnetic nickel ferrite/manganese dioxide (NiFe₂O₄/MnO₂) with 3D hierarchical flower-like and core-shell structure was synthesized by a facile hydrothermal approach and applied for the removal of Pb(II) ions from aqueous solutions. Batch adsorption experiments were conducted to study the effect of solution pH, initial Pb(II) concentration, and dose of absorbents on the Pb(II) removal by NiFe₂O₄/MnO₂. The NiFe₂O₄/MnO₂ nanocomposites showed the fast Pb(II) adsorption performance with the maximum adsorption capacity of 85.78mgg^-1. The adsorption kinetics of Pb(II) onto NiFe₂O₄/MnO₂ obeyed a pseudo-second-order model. The isothermal experimental results indicated that the Langmuir model was fitted better than the Freundlich model, illustrating a monolayer adsorption process for Pb(II) onto NiFe₂O₄/MnO₂. Meanwhile, the NiFe₂O₄/MnO₂ was easily separated from the solution by an external magnet within a short period of time and still exhibited almost 80% removal capacity after six regenerations. The NiFe₂O₄/MnO₂ is expected to be a new promising adsorbent for heavy metal removal.

Adsorption of mercury(ii) with an Fe3O4 magnetic polypyrrole–graphene oxide nanocomposite

The Fe₃O₄ magnetic polypyrrole–graphene (PPy–GO) has a Langmuir adsorption capacities of 400.0 mg g⁻¹ for Hg(ii). And it has a favorable saturation magnetization of 19.0 emu g⁻¹, easily separated from solutions via additional exterior magnets.

Facile synthesis of tea waste/Fe3O4nanoparticle composite for hexavalent chromium removal from aqueous solution

A tea waste/Fe₃O₄composite was prepared through chemical co-precipitation approach and was used for Cr(vi) removal, involving an adsorption-coupled reduction mechanism.

Synthesis and application of green mixed-metal oxide nano-composite materials from solid waste for dye degradation

Present study demonstrates reutilization of electrochemical (EC) sludge as a potential low-cost green catalyst for dye degradation. Hexagonal Fe2O3 type phase with trevorite (NiFe2O4)-type cubic phase nanocomposite material (NCM) was synthesized from solid waste sludge generated during EC treatment of textile industry wastewater with stainless steel electrode. For NCM synthesis, sludge was heated at different temperatures under controlled condition. Various synthesized NCMs were characterized by powder X-ray diffraction (PXD), energy dispersive X-ray (EDX) spectroscopy and X-ray photoelectron spectroscopy (XPS) analysis. The synthesized NCMs were found to contain iron, chromium, nickel and oxygen in the form of α-Fe2O3 (metal: oxygen = 40:60), (Fe,Cr,Ni)2O3 and trevorite NiFe2O4, (Ni,Fe,Cr) (Fe,Cr,Ni)2O4 (metal: oxygen = 43:57). Field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), pore size distribution, and atomic force microscope (AFM) analysis showed distribution of grains of different shapes and sizes. Catalytic activity of NCM was studied by the methylene red dye degradation by using the catalytic wet peroxidation process. Zeta potential study was performed under different pH so as to determine the performance of the NCMs during dye degradation.

Superparamagnetic bi-functional composite bead for the thermal ionization mass spectrometry of plutonium(iv) ions

Single resin bead-based thermal ionization mass spectrometry (TIMS) offers numerous advantages for Pu(iv) determinations in complex aqueous samples.

Designing a sulphonic acid functionalized benzimidazolium based poly(ionic liquid) for efficient adsorption of hexavalent chromium

Herein, the facile synthesis of sulphonic acid functioned benzimidazolium based poly(ionic liquid) (SBPIL) is reported for the first time and we investigated its efficacy towards the removal of Cr(vi).

A green adsorbent derived from banana peel for highly effective removal of heavy metal ions from water

A novel carbon foam (CF) was preparedviaphysically activating banana peel and applied for adsorbing various heavy metal ions including Cu²⁺, Pb²⁺, Cd²⁺and Cr⁶⁺in aqueous solution.

Polystyrene controlled growth of zerovalent nanoiron/magnetite on a sponge-like carbon matrix towards effective Cr(vi) removal from polluted water

Epoxide functionalized polystyrene controlled growth of zerovalent nanoiron/magnetite on a sponge-like carbon matrix (nZVI/Fe₃O₄@C) nanocomposites show a unique Cr(vi) removal performance over a wide pH range.

Synthesis of Fe3O4/P(St-AA) nanoparticles for enhancement of stability of the immobilized lipases

Core–shell Fe₃O₄/P(St-AA) nanoparticles were synthesized and employed as a magnetic carrier for lipase immobilization, and the properties of the immobilized lipase were studied.

Amino acid-based ionic liquid surface modification of magnetic nanoparticles for the magnetic solid-phase extraction of heme proteins

Amino acid-based ionic liquid functionalized magnetic nanoparticles were fabricated as an MSPE adsorbent for hemoglobin with a binding capacity of 1.58 g g⁻¹.

Hexavalent chromium induced tunable surface functionalization of graphite

Graphite with the oxygen related functional groups was achieved by functionalized with hexavalent chromium in certain conditions.

Facile preparation of amidoxime-functionalized fiber by microwave-assisted method for the enhanced adsorption of chromium(vi) from aqueous solution

In this study, a facile and highly efficient approach, the microwave-assisted (MW-aid) method, was applied for the synthesis of amidoxime-functionalized fibrous adsorbent, which exhibited enhanced adsorption capacities for Cr(vi) in aqueous solution.