Adsorbent For Environmental Remediation Research Articles

Valorization of Grain and Oil By-Products with Special Focus on Hemicellulose Modification.

Hemicellulose is one of the most important natural polysaccharides in nature. Hemicellulose from different sources varies in chemical composition and structure, which in turn affects the modification effects and industrial applications. Grain and oil by-products (GOBPs) are important raw materials for hemicellulose. This article reviews the modification methods of hemicellulose in GOBPs. The effects of chemical and physical modification methods on the properties of GOBP hemicellulose biomaterials are evaluated. The potential applications of modified GOBP hemicellulose are discussed, including its use in film production, hydrogel formation, three-dimensional (3D) printing materials, and adsorbents for environmental remediation. The limitations and future recommendations are also proposed to provide theoretical foundations and technical support for the efficient utilization of these by-products.

Theory-driven design of phosphazene-based porous polymer beads for enhanced iodine adsorption

Efficient adsorbents for radioiodine removal play a crucial role in safeguarding public and ecology health. However, conventional trial-and-error approaches for designing such high-performance adsorbents suffer from limited efficiencies. Herein, we employed a rational design strategy guided by precise density functional theory (DFT) calculations to synthesize a polyphosphazene-based microsphere tailored for iodine capture. Theoretical calculations quantifying the interactions of iodine molecules with diverse nitrogen-containing organic groups reveal the superior affinity of phosphazene groups with I2. Motivated by these findings, we judiciously designed a poly(bis(diethylamino)) phosphazene (PDEP) with a high density of active adsorption sites. Subsequently, PDEP was integrated into a composite bead with polyether sulfone (denote as PDEP@PES) for practical applications. PDEP@PES exhibits an elevated static adsorption capacity of 1.08 g/g, surpassing the majority of reported beads. More importantly, under a high flow rate of 200 mL/min, the dynamic uptake amount of PDEP@PES reaches 78.8 mg/g, outperforming pristine PES beads (3.19 mg/g) and commercial silver-impregnated silica gel (23.0 mg/g). The XPS results confirm the formation of robust charge-transfer complex between phosphazene groups with I2. This was further supported by their substantial interaction energy of -20.59 kcal/mol, as determined by DFT calculations. Our study demonstrates the high feasibility of polyphosphazene-based microspheres for radioiodine removal, shedding light on the enormous potential of theory-driven design paradigm for the development of exceptional adsorbents for environmental remediation.

Novel Adsorbents for Environmental Remediation

Exposure to environmental pollution due to the contamination of soil, surface and groundwater, and air poses potential health risks to biotic and abiotic ecosystems [...]

Cellulose based polyurethane with amino acid functionality: Design, synthesis, computational study and application in wastewater purification

Contamination in water is due to various environmental pollutants from natural and anthropogen activities. To remove toxic metals from contaminated water, we developed a novel adsorbent in foam form based on an olive industry waste material. The foam synthesis involved oxidation of cellulose extracted from the waste to dialdehyde, functionalization of the cellulose dialdehyde with an amino acid group, reacting the functionalized cellulose with hexamethylene diisocyanate and p-phenylene diisocyanate to produce the target polyurethanes Cell-F-HMDIC and Cell-F-PDIC, respectively. The optimum condition for lead(II) adsorption by Cell-F-HMDIC and Cell-F-PDIC were determined. The foams show the ability to quantitatively remove most of metal ions present in a real sample of sewage. The kinetic and thermodynamic studies confirmed a spontaneous metal ion binding to the foams with a second pseudo-order adsorption rate. The adsorption study revealed it obeys the Langmuir isotherm model. The experimental Qe values of both foams Cell-F-PDIC and Cell-F-HMDIC were 2.1929 and 2.0345 mg/g, respectively. Monte Carlo (MC) and Dynamic (MD) and simulations showed excellent affinity of both foams for lead ions with high adsorption negative energy value indicating vigorous interactions of Pb(II) with the adsorbent surface. The results indicate the usefulness of the developed foam in commercial applications. Environmental implicationElimination of metal ions from contaminated environments is important for a number of reasons. They are toxic to humans via interaction with biomolecules, resulting in disruption of the metabolism and biological activities of many proteins. They are toxic to plants. Industrial effluents and/or wastewater discharged from production processes, contain a considerable amount of metal ions.In this work, the use of naturally produced materials, such as olive waste biomass, as adsorbents for environmental remediation has received great attention. This biomass represents unused resources and presents serious disposal problems. We demonstrated that such materials are capable of selectively adsorbing metal ions.

Biochar as Sustainable Alternative and Green Adsorbent for the Remediation of Noxious Pollutants: A Comprehensive Review

The current water crisis necessitates the development of new materials for wastewater treatment. A variety of nanomaterials are continuously being investigated for their potential as adsorbents for environmental remediation. Researchers intend to develop a low-cost, simple, and sustainable material that can cater to removal of pollutants. Biochar derived from biowaste is a potential candidate for the existing problem of water pollution. The review focuses on the various aspects of biochar, such as its sources, preparation methods, mechanism, applications for wastewater treatment, and its regeneration. Compared with other adsorbents, biochar is considered as an environmentally friendly, sustainable, and cost-effective substitute for waste management, climate protection, soil improvement, wastewater treatment, etc. The special properties of biochar such as porosity, surface area, surface charge, and functional groups can be easily modified by various chemical methods, resulting in improved adsorption properties. Therefore, in view of the increasing environmental pollution and the problems encountered by researchers in treating pollutants, biochar is of great importance. This review also highlights the challenges and prospective areas that can be explored and studied in more detail in the future.

Application of hydroxyapatite-modified carbonized rice husk for the adsorption of Cr(VI) from aqueous solution

Agricultural and forestry waste biomasses have been widely used as adsorbents for environmental remediation with the advantages such as sustainability, economic efficiency, and excellent adsorption performance. A biochar-supported nano-Hydroxyapatite-modified carbonized rice husk (HAP@CRH) with high-efficiency and low-cost has been developed in our previous study. In this study, the effects of application condition parameters on the adsorption performance of HAP@CRH for Cr(VI) ions are further investigated. The results illustrate that 99.28 % Cr(VI) ions are removed at 50 °C, pH 2.0 with the adsorbent dosage of 5.0 g/L and the initial Cr(VI) ions concentration of 40 mg/L after adsorption equilibrium. The kinetic data is highly consistent with the pseudo-second-order model, indicating that the adsorption is mainly controlled by chemisorption. It also can be well-described by the the intra-particle diffusion model and Boyd’s film-diffusion kinetic model, indicating the external mass transport is a major process where particle diffusion is the rate-limiting step. Moreover, adsorption data is consistent with the Langmuir isotherm with an adsorption saturation capacity of 14.28 mg/g. It can be speculated that the adsorption mechanism includes physical adsorption, chemical adsorption, and ion exchange. Overall, the value of adsorption enthalpy change (ΔH) is 49.57 kJ/mol through thermodynamic calculations, which is over 40 kJ/mol, suggesting that the adsorption process is chemisorption, whcih is inherently spontaneous and exothermic, and the elevation of the temperature can result in the promotion of adsorption performance. It is anticipated that the composite of HAP@CRH with high adsorption capacity has the potential to be a newly developed adsorbent for Cr(VI) ions removal with a bright application prospect in environmental protection.

CuFe2O4@ hydroxyapatite composite for the environmental remediation of some heavy metal ions: Synthesis and characterization

ABSTRACT Tailoring highly efficient adsorbents for environmental remediation is a great challenge key. This paper reports the synthesis of nanostructured pure hydroxylapatite and hydroxyapatite coupled with copper ferrite CuFe2O4@HAp by simple routes for utilizing in the capture of some heavy metal ions like Fe(II) and Al(III) ions. The prepared CuFe2O4@HAp has the advantage of the feasible removal of the adsorbent materials after the treatment process by just exposing them to an external magnetic field. The obtained adsorbent has been characterized by several techniques; XRD patterns showed the high purity of the materials. Moreover, the morphological study by TEM revealed the size of the nanoparticles with a needlelike shape that had a length of 21.9 to 44.04 nm and a cross-sectional dimension of 7.15 to 7.83 nm. Factors like contact time, pH, and the initial concentration have been investigated. Furthermore, different isothermic and kinetic models have been also simulated to study the adsorption performance of CuFe2O4@HAp. The obtained results revealed that this adsorbent could be a promising, safe, and sustainable inexpensive material for the wastewater treatment processes.

Cryostructurization of polymeric systems for developing macroporous cryogel as a foundational framework in bioengineering applications

Among various fabrication techniques to produce a porous scaffold, thermally-induced phase separation at controlled cryogenic condition leads to the formation of a porous polymeric cryostructure alias cryogel or cryomatrix. Cryostructurization is one of the simple and versatile methods of synthesizing a highly porous and interconnected architecture. The process of cryostructurization is present in comparable fabrication approach of fabricating advanced porous biomaterials with precise control over multiple compositions of precursor units, spatial distributions for accomplishing effective recapitulation of mechanical properties and architectural accuracy at micron-scale with bioactive functionality. The cryogenically-structured polymeric scaffolds are of noteworthy fundamental and applied interest in multi-disciplinary areas of science and showed promising matrices in various biotechnological and biomedical areas. The large interconnected pores in cryogels open up a range of applications like the three-dimensional substrate for cell growth, bioreactor for continuous production of scarce molecules, bio-processing and protein purification, an adsorbent for environmental remediation, and biosensor fabrication. Over the past two decades, significant attention to these materials with rigorous expansion in their new designs, and remarkable growth in the number of the publications and patents on cryostructured porous materials has been noticed. This article is covering the progress in cryostructurization technology in the last few decades with principles underlying the mechanism of cryogelation, process optimization, and the recent trend in cryogel for biomedical and bioengineering applications. The genesis of a highly porous interconnected architecture by the process of thermally-induced phase separation under cryo-temperature which is commonly known as cryostructurization of polymeric systems to produce porous scaffolds can be synthesized using a variety of polymer precursors for multidisciplinary applications in the fields of biomedicine, environment and bioengineering.

Effects of the pyrolysis temperature on the biotoxicity of Phyllostachys pubescens biochar in the aquatic environment.

The use of biochar as an adsorbent for environmental remediation has been attracting increasing interest. However, biochar can contain contaminants such as polycyclic aromatic hydrocarbons (PAHs) and metals (e.g., Cu, Pb, and Zn). We prepared Phyllostachys pubescens biochars at temperatures between 400 and 700 °C. The biochars were used in bioassays using Vibrio qinghaiensis Q67, Daphnia magna, Pseudokirchneriella subcapitata, and Limnodrilus hoffmeisteri to characterize the toxicities and effects of the biochars. The PAH, Cu, Pb, and Zn contents of the biochars were 8.59-14.67, 1.82-3.26, 1.17-3.53, and 8.76-16.47 mg/kg, respectively. The biochars gave maximum P. subcapitata, D. magna, and V. qinghaiensis Q67 inhibition rates of 6.47%, 6.70%, and 29.87%, respectively. The biochars produced at high pyrolysis temperatures (≥600 °C) had low acute biotoxicities to L. hoffmeisteri and barely affected L. hoffmeisteri biomass, reproduction, and lipid content. The biochars may therefore be suitable for sediment remediation.

Hexavalent chromium removal over magnetic carbon nanoadsorbents: synergistic effect of fluorine and nitrogen co-doping

F and N co-doped magnetic nanocarbons as adsorbents for environmental remediation have been demonstrated for the first time with high efficiency.

Facile synthesis of Fe3O4/MoS2 nanohybrid for solid phase extraction of Ag(I) and Pb(II): kinetic, isotherm and thermodynamic studies

ABSTRACTRecently, MoS2 with abundant electron density in its structure attracted more attention as an adsorbent for environmental remediation. However, hard manipulation of target solution owing to high dispersibility in aqueous media restricts its application as adsorbent. Preparation of Fe3O4/MoS2 nanohybrid can solve this problem. Also, this nanohybrid improves adsorption capacities of target ions. In this work, Fe3O4 nanoparticles, MoS2 nanosheets and hybrid of these two were synthesised and then characterised by X-ray diffraction, energy-dispersive X-ray spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, Fourier transforms infrared spectra, Brunauer–Emmett–Teller surface area and vibrating sample magnetometer. Subsequently, adsorption of Ag(I) and Pb(II) ions from aqueous solution by these three adsorbents was examined in detail and compared with each other while the adsorption conditions including the pH value, contact time, dosage of sorbent, elution conditions and interfering ions have been optimised. According to obtained results, prepared nanohybrid showed enhanced adsorption capacities for both ions relative to naked Fe3O4 and MoS2. The limits of detection for Ag(I) and Pb(II) were calculated as 0.49 µg L−1 and 2.7 µg L−1, respectively, and the relative standard deviation percentages (n = 5) for Ag(I) and Pb(II) were 2.8%, and 3.0%, respectively. Furthermore, the preconcentration factors were 300 and 75 for Ag(I) and Pb(II) ions, respectively. Moreover, kinetic studies showed that pseudo-second-order model can better describe target analytes adsorption properties by every three adsorbents. Regeneration of the adsorbents was performed with HCl/thiourea mixture.

INFLUENCE OF PURIFICATION PROCESS ON THE CHARACTERISTICS OF ROMANIAN CALCIUM BENTONITE

A calcium bentonite from Orasu Nou deposit (Romania) was used as raw material. The natural bentonite provided by S.C. Bentonita S.A., Satu Mare has the following mineralogical composition: 57 % montmorillonite, 40 % cristobalite, and 3 % quartz. Due to the relatively high percentage of impurities in natural calcium bentonite, we decided to purify the raw material, in order to improve the quality of montmorillonite. Through purification procedure, well defined granulometric fractions with particles of less than 2 μm, are obtained. The crude and purified calcium bentonites were characterized by textural analysis, scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDX). The physical, structural and morphological characteristics are affected by the purification process. The purified bentonite can be used to obtain advanced materials, which can be tested as adsorbents for environmental remediation.

Nano-TiO2 modified with natural and chemical compounds as efficient adsorbents for the removal of Cd+2, Cu+2, and Ni+2 from water

Nanoparticles (NPs) modified with proper compounds are now gaining much attention for their function as new adsorbents for environmental remediation. The main objective of this study is to determine the effectiveness of modified nanoparticles (MNPs) as sorbents in removing Cd+2, Cu+2, and Ni+2 from single and competitive solutions by TiO2 NPs modified with humic acid (Ti–H), extractant of Walnut shell (Ti–W), and 1, 5 diphenyl-Carbazon (Ti–C). MNPs were characterized by XRD, FT-IR, and SEM–EDX analyzer. The MNPs were spherical in shape. The mean diameter of MNPs was determined to be 64.7 nm. The sorption of Cd+2 and Cu+2 on MNPs fitted better in Langmuir model than Freundlich model. But Ni+2 sorption better fitted in Freundlich model. Kinetics of adsorption follow pseudo-second order kinetic model than pseudo-first-order kinetic model. The adsorption maximum was observed at pH 7. Adsorption capacities of MNPs were obtained from Langmuir model and final point of isotherm. Comparison with published adsorption capacities for other adsorbents indicated that Ti–W and Ti–C had potential as proper adsorbents for the removal of Cd+2 and Cu+2 from single and competitive aqueous solution and Ti–H was a good candidate for Ni+2 removal from single and competitive solutions.

Conductive resilient graphene aerogel via magnesiothermic reduction of graphene oxide assemblies

Graphene aerogels are desirable for energy storage and conversion, as catalysis supports, and as adsorbents for environmental remediation. To produce graphene aerogels with low density, while maintaining high electrical conductivity and strong mechanic performance, we synthesized graphene aerogels by the magnesiothermic reduction of a freeze-dried graphene oxide (GO) self-assembly and subsequent etching of the formed MgO in acid solution. The reduced graphene oxide (rGO) aerogel samples exhibited densities as low as 1.1 mg·cm−3. The rGO aerogel was very resilient, exhibiting full recoveryeven after being compressed by strains of up to 80%; its elastic modulus (E) scaled with density (ρ) as E∼ρ2. The rGO aerogels also exhibited high conductivities (e.g., 27.7 S·m−1 at 3.6 mg·cm−3) and outperformed many rGO aerogels fabricated by other reduction processes. Such outstanding properties were ascribed to the microstructures inherited from the freeze-dried GO self-assembly and the magnesiothermic reduction process.

Removal of Copper from Aqueous Solution using Tunisian Clay

Natural adsorbents such as clay was used to replace expensive imported synthetic adsorbents. In this study, Scanning Electron Microscopy (SEM), Infrared spectroscopy and X-ray diffraction techniques were used to characterize the used sorbent (clays C). Batch experiments were performed to evaluate the effects of contact time, solution pH and temperature on copper removal onto used sorbent from aqueous solution. Equilibrium data were analyzed using Langmuir and Freundlich isotherm models to calculate isotherm constants. Kinetic studies showed that an equilibrium time of 1 h was required for the adsorption of Cu(II) onto Tunisian clay. Equilibrium adsorption is affected by the initial pH of the solution. The maximum adsorption capacity was obtained at pH 5. Adsorption tests in synthetic wastewater revealed that the adsorption data of this material for copper ions were better fit to the Langmuir isotherm based on correlation coefficients. The influence of temperature on the adsorption process was also evaluated. Results indicated that adsorption of Cu(II) on the sorbents is endothermic. The thermodynamic parameters (I”G°,I”H° and I”S°) for Cu(II) sorption were also determined from the temperature dependence. Results of this study suggest that used Tunisian clay may be a promising adsorbents for environmental remediation.