scholarly journals IMMOBILIZATION OF HUMIC ACID ON CHITOSAN BEADS BY PROTECTED CROSS-LINKING METHOD AND ITS APPLICATION AS SORBENT FOR Pb(II)

2010 ◽  
Vol 10 (1) ◽  
pp. 88-95
Author(s):  
Radna Nurmasari ◽  
Uripto Trisno Santoso ◽  
Dewi Umaningrum ◽  
Taufiqur Rohman
Keyword(s):  
Humic Acid ◽  
Adsorption Capacity ◽  
Active Sites ◽  
Cross Linking ◽  
Basic Solution ◽  
Chitosan Beads ◽  
Reaction Method ◽  
The Cross

Immobilization of humic acid (HA) on chitosan beads has been done using a protected cross-linking reaction method and the product was then utilized as sorbent for Pb(II). Protection of the active sites of HA was carried out by interacting HA with Pb(II) before performing the cross-linking reaction in order to maintain its adsorption capacity. Protected-HA was cross-linked with chitosan beads using glutaraldehyde in order to obtain sorbent insoluble both in aqueous acidic and basic solution. The result showed that the amount of immobilized HA on beads chitosan was 88.60% by weight. The adsorption capacity of the protected-sorbent beads for Pb(II) was 784 mg/g. As a comparison, the adsorption capacity of the non-protected sorbent beads for Pb(II) was only 142 mg/g.   Keywords: immobilization, adsorption, crosslinking, humic acid, chitosan

scholarly journals IMMOBILIZATION OF HUMIC ACID ON CHITOSAN USING PROTECTED CROSS-LINKING REACTION METHOD AND ITS APPLICATION AS SORBENT FOR Pb(II), Cd(II), AND Cr(III)

2010 ◽  
Vol 8 (2) ◽  
pp. 177-183
Author(s):  
Uripto Trisno Santoso ◽  
Dewi Umaningrum ◽  
Utami Irawati ◽  
Radna Nurmasari
Keyword(s):  
Humic Acid ◽  
Adsorption Capacity ◽  
Active Sites ◽  
Cross Linking ◽  
Basic Solution ◽  
Reaction Method ◽  
The Cross

Immobilization of humic acid (HA) on chitosan has been done by using a protected cross-linking reaction method and the product was then utilized as sorbent for Pb(II), Cd(II), and Cr(III). HA was cross-linked with chitosan by using glutaraldehyde in order to obtain sorbent insoluble in aqueous acidic and basic solution. Protection of the active sites of HA was carried out by interacting HA with Pb(II) before performing the cross-lingking reaction in order to maintain its adsorption capacity The result showed that the amount of immobilized HA on chitosan was 99.7% by weight. The solubility of the immobilized HA were < 0.5% at pH 6 and < 1.0% at pH 12. The amount of immobilized HA and its solubility indicated that the protection pretreatment did not interfere the cross-linking reaction between HA and chitosan. The adsorption capacity of the sorbent for Pb(II), Cd(II), and Cr(III) were 416.7 mg/g, 332.3 mg/g, dan 714.3 mg/g, respectively.   Keywords: immobilization, cross-linking, humic acid, chitosan, sorbent

Development of chitosan-based granular adsorbents for enhanced and selective adsorption performance in heavy metal removal

2006 ◽  
Vol 54 (10) ◽  
pp. 103-113 ◽  
Author(s):  
N. Li ◽  
R. Bai
Keyword(s):  
Heavy Metal ◽  
Metal Ions ◽  
Adsorption Capacity ◽  
Selective Adsorption ◽  
Cross Linking ◽  
The Novel ◽  
Chitosan Beads ◽  
Hydrogel Beads ◽  
Amine Groups ◽  
The Cross

Novel chitosan-based granular adsorbents were developed for enhanced and selective separation of heavy metal ions. The research included the synthesis of chitosan hydrogel beads, the cross-linking of the hydrogel beads with ethylene glycol diglycidyl ether (EGDE) in a conventional and a novel amine-shielded method, the functionalization of the chitosan beads through surface grafting of polyacrylamide via a surface-initiated atom transfer radical polymerization (ATRP) method, and the examination of the adsorption performance of the various types of chitosan beads in the removal of heavy metal ions. It was found that chitosan beads were effective in heavy metal adsorption, the conventional cross-linking method improved the acidic stability of the beads but reduced their adsorption capacity, the novel amine-shielded cross-linking method retained the good adsorption capacity while it improved the acidic stability of the beads, and the grafting of polyacrylamide on chitosan beads not only enhanced the adsorption capacity but also provided the beads with excellent selectivity for mercury over lead ions. XPS analyses indicated that the adsorption of metal ions on chitosan beads was mainly attributed to the amine groups of chitosan, the novel amine-shielded cross-linking method preserved most of the amine groups from being consumed by the cross-linking process and hence improved the adsorption capacity of the cross-linked chitosan beads, and the many amide groups from the polyacrylamide grafted on the chitosan beads increased the adsorption capacity and also made possible selective adsorption of mercury ions because the amide groups can form covalent bonds with mercury ions.

scholarly journals Investigation of the functional network modifier loading on the stoichiometric ratio of epoxy resins and their dielectric properties

2021 ◽  
Author(s):  
Istebreq A. Saeedi ◽  
Sunny Chaudhary ◽  
Thomas Andritsch ◽  
Alun S. Vaughan
Keyword(s):  
Glass Transition ◽  
Dielectric Properties ◽  
Electrical Properties ◽  
Epoxy Resins ◽  
Functional Network ◽  
Cross Linking ◽  
Network Modifier ◽  
Epoxy Resin System ◽  
The Cross ◽  
The Impact

AbstractReactive molecular additives have often been employed to tailor the mechanical properties of epoxy resins. In addition, several studies have reported improved electrical properties in such systems, where the network architecture and included function groups have been modified through the use of so-called functional network modifier (FNM) molecules. The study reported here set out to investigate the effect of a glycidyl polyhedral oligomeric silsesquioxane (GPOSS) FNM on the cross-linking reactions, glass transition, breakdown strength and dielectric properties of an amine-cured epoxy resin system. Since many previous studies have considered POSS to act as an inorganic filler, a key aim was to consider the impact of GPOSS addition on the stoichiometry of curing. Fourier transform infrared spectroscopy revealed significant changes in the cross-linking reactions that occur if appropriate stoichiometric compensation is not made for the additional epoxide groups present on the GPOSS. These changes, in concert with the direct effect of the GPOSS itself, influence the glass transition temperature, dielectric breakdown behaviour and dielectric response of the system. Specifically, the work shows that the inclusion of GPOSS can result in beneficial changes in electrical properties, but that these gains are easily lost if consequential changes in the matrix polymer are not appropriately counteracted. Nevertheless, if the system is appropriately optimized, materials with pronounced improvements in technologically important characteristics can be designed.

scholarly journals The Effect of Surfactant-Modified Montmorillonite on the Cross-Linking Efficiency of Polysiloxanes

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2623
Author(s):  
Monika Wójcik-Bania ◽  
Jakub Matusik
Keyword(s):  
Total Pore Volume ◽  
Cross Linking ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
The Cross ◽  
Chain Lengths ◽  
First Time ◽  
Substituent Influence ◽  
Benzyl Substituent

Polymer–clay mineral composites are an important class of materials with various applications in the industry. Despite interesting properties of polysiloxanes, such matrices were rarely used in combination with clay minerals. Thus, for the first time, a systematic study was designed to investigate the cross-linking efficiency of polysiloxane networks in the presence of 2 wt % of organo-montmorillonite. Montmorillonite (Mt) was intercalated with six quaternary ammonium salts of the cation structure [(CH3)2R’NR]+, where R = C12, C14, C16, and R’ = methyl or benzyl substituent. The intercalation efficiency was examined by X-ray diffraction, CHN elemental analysis, and Fourier transform infrared (FTIR) spectroscopy. Textural studies have shown that the application of freezing in liquid nitrogen and freeze-drying after the intercalation increases the specific surface area and the total pore volume of organo-Mt. The polymer matrix was a poly(methylhydrosiloxane) cross-linked with two linear vinylsiloxanes of different siloxane chain lengths between end functional groups. X-ray diffraction and transmission electron microscopy studies have shown that the increase in d-spacing of organo-Mt and the benzyl substituent influence the degree of nanofillers’ exfoliation in the nanocomposites. The increase in the degree of organo-Mt exfoliation reduces the efficiency of hydrosilylation reaction monitored by FTIR. This was due to physical hindrance induced by exfoliated Mt particles.

scholarly journals Study on the adsorption selection of CH$$_4$$ on CuO (110) versus (111) surfaces: a density functional theory study

2021 ◽  
Vol 3 (4) ◽  
Author(s):  
Long Lin ◽  
Linwei Yao ◽  
Shaofei Li ◽  
Zhengguang Shi ◽  
Kun Xie ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Adsorption Capacity ◽  
Active Sites ◽  
Density Functional ◽  
Oxygen Vacancies ◽  
Density Functional Theory Calculations ◽  
Density Functional Theory Study ◽  
Functional Theory ◽  
Strong Adsorption ◽  
Selection Of

AbstractFinding the active sites of suitable metal oxides is a key prerequisite for detecting CH$$_4$$ 4 . The purpose of the paper is to investigate the adsorption of CH$$_4$$ 4 on intrinsic and oxygen-vacancies CuO (111) and (110) surfaces using density functional theory calculations. The results show that CH$$_4$$ 4 has a strong adsorption energy of −0.370 to 0.391 eV at all site on the CuO (110) surface. The adsorption capacity of CH$$_4$$ 4 on CuO (111) surface is weak, ranging from −0.156 to −0.325 eV. In the surface containing oxygen vacancies, the adsorption capacity of CuO surface to CH$$_4$$ 4 is significantly stronger than that of intrinsic CuO surface. The results indicate that CuO (110) has strong adsorption and charge transfer capacity for CH$$_4$$ 4 , which may provide experimental guidance.

Effects of a crosslinking agent on a supramolecular gel to control lost circulation

2021 ◽  
Vol 45 (16) ◽  
pp. 7089-7095
Author(s):  
Bo Wang ◽  
Jinsheng Sun ◽  
Kaihe Lv ◽  
Feng Shen ◽  
Yingrui Bai
Keyword(s):  
Crosslinking Agent ◽  
Network Density ◽  
Cross Linking ◽  
Supramolecular Gel ◽  
Lost Circulation ◽  
The Cross

The Cr3+ can improve the cross-linking degree and network density of the GP-A gel, and enhance its strength and plugging ability to control lost circulation.

A framework ensemble facilitates high Pt utilization in a low Pt loading fuel cell

2021 ◽  
Vol 11 (8) ◽  
pp. 2957-2963
Author(s):  
Jian Wang ◽  
Guangping Wu ◽  
Wenhui Xuan ◽  
Lishan Peng ◽  
Yong Feng ◽  
...  
Keyword(s):  
Fuel Cell ◽  
Phase Field ◽  
Active Sites ◽  
Catalyst Layer ◽  
Three Phase ◽  
Pt Utilization ◽  
The Cross ◽  
Low Pt Loading ◽  
Effective Transfer

Rationally designing the structure of catalyst layer in MEA to achieve the dispersion of active sites at the cross of three-phase field and the effective transfer network paths for protons through catalysts and catalyst layer.

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