Graphene/waste-newspaper cellulose composite aerogels with selective adsorption of organic dyes: preparation, characterization, and adsorption mechanism

2020 ◽  
Vol 44 (6) ◽  
pp. 2256-2267 ◽  
Author(s):  
Chuting Feng ◽  
Penggang Ren ◽  
Zhen Li ◽  
Wenzhen Tan ◽  
Hua Zhang ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Freeze Drying ◽  
Adsorption Mechanism ◽  
Organic Dyes ◽  
Selective Adsorption ◽  
Sol Gel ◽  
Dye Wastewater ◽  
Graphene Composite ◽  
Composite Aerogels ◽  
Cellulose Composite

Waste-newspaper cellulose/graphene composite aerogels were facilely synthesized via the sol–gel and freeze-drying processes for dye wastewater treatment.

Cellulose-Silica Composite Aerogels Prepared with Sodium Silicate by Freeze Drying Method

2016 ◽  
Vol 697 ◽  
pp. 129-133 ◽  
Author(s):  
Hua Zheng Sai ◽  
Rui Fu ◽  
Li Xing ◽  
Jun Hui Xiang ◽  
Zhen You Li ◽  
...  
Keyword(s):  
Freeze Drying ◽  
Sol Gel ◽  
Cellulose Nanofibers ◽  
Compression Modulus ◽  
High Specific Surface Area ◽  
Regenerated Cellulose ◽  
Organic Precursor ◽  
Silica Composite ◽  
Composite Aerogels ◽  
Solvent Replacement

The cellulose-silica composite aerogels (CAs) were fabricated through a permeation sol-gel process in the regenerated cellulose hydrogels followed by freeze drying. The precursor Na2SiO3 instead of traditional organic precursor was diffused in the cellulose matrix followed by permeating the catalyst into the cellulose nanofibers network gradually to promote the in situ condensation of Na2SiO3 to form a SiO2 gel skeleton from outside to inside. The obtained CAs displayed the interpenetrating network (IPN) structure of the regenerated cellulose nanofibers network and the SiO2 gel skeleton in nanoscale. In the IPN structure, the flexible cellulose nanofibers network was supported by the hard inorganic network effectively to sustain the compression and the silica gel skeleton protect the cellulose nanofibers to avoid the remodeling of their shape in the process of solvent replacement before freeze drying. Due to the synergic effects of the different network, the IPN structure endows the CAs with high compression modulus (as high as 15.48 MPa), high specific surface area (as high as 621 m2 g-1) and low density (less than 0.182 g cm-3).

Construction of a 3D multiple network skeleton by the thiol-Michael addition click reaction to fabricate novel polymer/graphene aerogels with exceptional thermal conductivity and mechanical properties

2017 ◽  
Vol 5 (42) ◽  
pp. 22352-22360 ◽  
Author(s):  
Shiqiang Song ◽  
Yong Zhang
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Freeze Drying ◽  
Click Reaction ◽  
Porous Polymer ◽  
Compressive Properties ◽  
Graphene Composite ◽  
Drying Procedures ◽  
Composite Aerogels ◽  
Multiple Network

Novel porous polymer/graphene composite aerogels with a multiple network structure, enhanced compressive properties and high thermal conductivity are first fabricated by adsorbing water vapour, reduction, and freeze-drying procedures.

scholarly journals Microstructure and filtration performance of konjac glucomannan-based aerogels strengthened by wheat straw

2017 ◽  
Vol 14 (3) ◽  
pp. 335-343 ◽  
Author(s):  
Yixin Wang ◽  
Xi Chen ◽  
Ying Kuang ◽  
Man Xiao ◽  
Yuehong Su ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Wheat Straw ◽  
Freeze Drying ◽  
Sol Gel ◽  
Compression Modulus ◽  
Filtration Efficiency ◽  
Konjac Glucomannan ◽  
Filtration Resistance ◽  
Composite Aerogels

Abstract This study presents the preparation and measurement of a novel environmentally friendly konjac glucomannan (KGM)-based composite aerogels enhanced with wheat straw (WS) via a sol–gel and freeze-drying progress. With the addition of WS, the porosity of aerogels could be increased from 50 to 88.13%, the filtration resistance of aerogels could be reduced from 500 to 205 Pa, and the filtration efficiency could be improved to 90.38%. The addition of WS also enhances the mechanical properties of composite aerogels with compression modulus of 2000.66 Pa, compressive strength of 501.56 Pa and elasticity of 0.603. The results demonstrate the high potential of KGM-based composite aerogels enhanced with WS for applications in air filtering.

scholarly journals Functionalized Materials as a Versatile Platform for Enzyme Immobilization in Wastewater Treatment

2021 ◽  
Author(s):  
Agnieszka Kołodziejczak-Radzimska ◽  
Long D. Nghiem ◽  
Teofil Jesionowski
Keyword(s):  
Wastewater Treatment ◽  
Enzyme Immobilization ◽  
Organic Dyes ◽  
Scientific Progress ◽  
Immobilized Enzymes ◽  
Chemical Oxidation ◽  
Biologically Active ◽  
Water Pollutants ◽  
Untreated Wastewater ◽  
Functionalized Materials

Abstract Purpose of Review Untreated wastewater discharge can significantly and negatively impact the state of the environment. Rapid industrialization and economic development have directly contributed to land and water pollution resulting from the application of many chemicals such as organic dyes, pharmaceuticals, and industrial reagents. The removal of these chemicals before effluent discharge is crucial for environmental protection. This review aims to explore the importance of functionalized materials in the preparation of biocatalytic systems and consider their application in eliminating water pollutants. Recent Findings Wastewater treatment methods can be classified into three groups: (i) chemical (e.g., chemical oxidation and ozonation), (ii) physical (e.g., membrane separation and ion exchange), and (iii) biological processes. Biological treatment is the most widely used method due to its cost-effectiveness and eco-friendliness. In particular, the use of immobilized enzymes has recently become more attractive as a result of scientific progress in advanced material synthesis. The selection of an appropriate support plays an important role in the preparation of such biologically active systems. Recent studies have demonstrated the use of various materials for enzyme immobilization in the purification of water. Summary This review identifies and discusses different biocatalytic systems used in the enzymatic degradation of various water pollutants. Materials functionalized by specific groups can serve as good support matrices for enzyme immobilization, providing chemical and thermal stability to support catalytic reactions. Enzymatic biocatalysis converts the pollutants into simpler products, which are usually less toxic than their parents. Due to immobilization, the enzyme can be used over multiple cycles to reduce the cost of wastewater treatment. Future studies in this field should focus on developing new platforms for enzyme immobilization in order to improve degradation efficiency.

scholarly journals Elucidation of the Crystal Growth Characteristics of SnO2 Nanoaggregates Formed by Sequential Low-Temperature Sol-Gel Reaction and Freeze Drying

Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1738
Author(s):  
Saeid Vafaei ◽  
Alexander Wolosz ◽  
Catlin Ethridge ◽  
Udo Schnupf ◽  
Nagisa Hattori ◽  
...  
Keyword(s):  
Crystal Growth ◽  
Low Temperature ◽  
Photoelectron Spectroscopy ◽  
High Performance ◽  
Freeze Drying ◽  
Sno2 Nanoparticles ◽  
Sol Gel ◽  
Functional Materials ◽  
Cost Effective ◽  
High Concentration

SnO2 nanoparticles are regarded as attractive, functional materials because of their versatile applications. SnO2 nanoaggregates with single-nanometer-scale lumpy surfaces provide opportunities to enhance hetero-material interfacial areas, leading to the performance improvement of materials and devices. For the first time, we demonstrate that SnO2 nanoaggregates with oxygen vacancies can be produced by a simple, low-temperature sol-gel approach combined with freeze-drying. We characterize the initiation of the low-temperature crystal growth of the obtained SnO2 nanoaggregates using high-resolution transmission electron microscopy (HRTEM). The results indicate that Sn (II) hydroxide precursors are converted into submicrometer-scale nanoaggregates consisting of uniform SnO2 spherical nanocrystals (2~5 nm in size). As the sol-gel reaction time increases, further crystallization is observed through the neighboring particles in a confined part of the aggregates, while the specific surface areas of the SnO2 samples increase concomitantly. In addition, X-ray photoelectron spectroscopy (XPS) measurements suggest that Sn (II) ions exist in the SnO2 samples when the reactions are stopped after a short time or when a relatively high concentration of Sn (II) is involved in the corresponding sol-gel reactions. Understanding this low-temperature growth of 3D SnO2 will provide new avenues for developing and producing high-performance, photofunctional nanomaterials via a cost-effective and scalable method.

Utilization of cationic polymer-modified fly ash for dye wastewater treatment

2021 ◽  
Author(s):  
Jingye Zhou ◽  
Kai Xia ◽  
Xin Liu ◽  
Long Fang ◽  
Hui Du ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Fly Ash ◽  
Cationic Polymer ◽  
Dye Wastewater ◽  
Modified Fly Ash

scholarly journals Chitosan/Zeolite Composite Aerogels for a Fast and Effective Removal of Both Anionic and Cationic Dyes from Water

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1691
Author(s):  
Angela Marotta ◽  
Enrica Luzzi ◽  
Martina Salzano de Luna ◽  
Paolo Aprea ◽  
Veronica Ambrogi ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Broad Spectrum ◽  
Organic Dyes ◽  
Indigo Carmine ◽  
Zeolite 13X ◽  
Industrial Sectors ◽  
Effective Removal ◽  
Composite Aerogels ◽  
Zeolite Composite ◽  
Adsorption Desorption

Organic dyes are extensively used in many industrial sectors, and their uncontrolled disposal into wastewaters raises serious concerns for environmental and human health. Due to the large variety of such pollutants, an effective remediation strategy should be characterized by a broad-spectrum efficacy. A promising strategy is represented by the combination of different adsorbent materials with complementary functionalities to develop composite materials that are expected to remove different contaminants. In the present work, a broad-spectrum adsorbent was developed by embedding zeolite 13X powder (ZX) in a chitosan (CS) aerogel (1:1 by weight). The CS–ZX composite adsorbent removes both anionic (indigo carmine, IC) and cationic (methylene blue, MB) dyes effectively, with a maximum uptake capacity of 221 mg/g and 108 mg/g, respectively. In addition, the adsorption kinetics are rather fast, with equilibrium conditions attained in less than 2 h. The composite exhibits good mechanical properties in both dry and wet state, which enables its handling for reusability purposes. In this regard, preliminary tests show that the full restoration of the IC removal ability over three adsorption–desorption cycles is achieved using a 0.1 M NaOH aqueous solution, while a 1 M NaCl aqueous solution allows one to preserve >60% of the MB removal ability.

scholarly journals Effects of Electronegativity and Hydration Energy on the Selective Adsorption of Heavy Metal Ions by Synthetic NaX Zeolite

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4066
Author(s):  
Xianyuan Fan ◽  
Hong Liu ◽  
Emmanuella Anang ◽  
Dajun Ren
Keyword(s):  
Heavy Metal ◽  
Metal Ions ◽  
Adsorption Capacity ◽  
Heavy Metal Ions ◽  
Binary Systems ◽  
Adsorption Mechanism ◽  
Selective Adsorption ◽  
Hydration Energy ◽  
Nax Zeolite ◽  
High Electronegativity

The adsorption capacity of synthetic NaX zeolite for Pb2+, Cd2+, Cu2+ and Zn2+ in single and multi-component systems were investigated. The effects of electronegativity and hydration energy on the selective adsorption, as well as potential selective adsorption mechanism of the NaX zeolite for Pb2+, Cd2+, Cu2+ and Zn2+ were also discussed. The maximum adsorption capacity order of the heavy metals in the single system was Pb2+ > Cd2+ > Cu2+ > Zn2+, and this could be related to their hydration energy and electronegativity. The values of the separation factors (α) and affinity constant (KEL) in different binary systems indicated that Pb2+ was preferentially adsorbed, and Zn2+ presented the lowest affinity for NaX zeolite. The selective adsorption capacities of the metals were in the order, Pb2+ > Cd2+ ≈ Cu2+ > Zn2+. The trend for the selective adsorption of NaX zeolite in ternary and quaternary systems was consistent with that in the binary systems. Pb2+ and Cu2+ reduced the stability of the Si-O-Al bonds and the double six-membered rings in the NaX framework, due to the high electronegativity of Pb2+ and Cu2+ than that of Al3+. The selective adsorption mechanism of NaX zeolite for the high electronegative metal ions could mainly result from the negatively charged O in the Si-O-Al structure of the NaX zeolite, hence heavy metal ions with high electronegativity display a strong affinity for the electron cloud of the oxygen atoms in the Si-O-Al. This study could evaluate the application and efficiency of zeolite in separating and recovering certain metal ions from industrial wastewater.

An Anionic Indium–Organic Framework with Spirobifluorene-Based Ligand for Selective Adsorption of Organic Dyes

2021 ◽  
Vol 60 (3) ◽  
pp. 1571-1578
Author(s):  
Xinli Shi ◽  
Yucong Zu ◽  
Shuangshuang Jiang ◽  
Fuxing Sun
Keyword(s):  
Organic Dyes ◽  
Selective Adsorption ◽  
Organic Framework
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