Regulation of the point of zero charge and surface acidity constants of γ-Al2O3, using sodium and fluoride ions as modifiers

1984 ◽  
pp. 1309-1310 ◽  
Author(s):  
L. Vordonis ◽  
P. G. Koutsoukos ◽  
A. Lycourghiotis
Keyword(s):  
Surface Acidity ◽  
Point Of Zero Charge ◽  
Acidity Constants ◽  
Fluoride Ions ◽  
Zero Charge

scholarly journals Temperature Effect on the Surface Properties of ZnO(am)

1997 ◽  
Vol 15 (10) ◽  
pp. 789-802 ◽  
Author(s):  
S. Mustafa ◽  
Shahida Parveen ◽  
Aftab Ahmad ◽  
Dilara Begum
Keyword(s):  
Zinc Oxide ◽  
Temperature Effect ◽  
Thermodynamic Parameters ◽  
Dissociation Constants ◽  
Surface Acidity ◽  
Point Of Zero Charge ◽  
Acidity Constants ◽  
Zero Charge ◽  
Increasing Temperature ◽  
Thomas Equation

The point of zero charge and surface acidity constants of zinc oxide were determined over the temperature range 293–323 K. Both the point of zero charge (pzc) and the surface acidity constants (pKa1 and pKa2) were found to decrease with increasing temperature. The values of the dissociation constants (pKa1 and pKa2) determined from the Henderson-Hasselbach equation agreed very well with those determined using the Gaines-Thomas equation. The thermodynamic parameters ΔH0 and ΔS0 for the processes were also evaluated.

scholarly journals Modification of the surface chemistry of activated carbon and its influence on methylene blue adsorption

2018 ◽  
Vol 5 (1) ◽  
pp. 374
Author(s):  
David Wibowo ◽  
Lanny Setyadhi ◽  
Suryadi Ismadji
Keyword(s):  
Methylene Blue ◽  
Activated Carbon ◽  
Surface Chemistry ◽  
Activated Carbons ◽  
Surface Acidity ◽  
Carbon Surface ◽  
Point Of Zero Charge ◽  
Titration Method ◽  
Zero Charge ◽  
Boehm Titration

The adsorption behavior of activated carbons is determined not only by their porous structures but also by the chemical nature of its surface. The surface chemistry of activated carbons can be selectively modified in order to improve their adsorption capacity. In this study, a NORIT granular activated carbon was treated by oxidant (HNO3) and non-oxidant acid (HCI) at different concentrations and temperatures. The surface chemistries of the materials were characterized by Boehm titration method and by the determination of the point of zero charge (pHPZC).The adsorption properties of the selected samples were studied by adsorption of methylene blue, which is one of the important dyes and found in many textile effluents. In addition, the pore structures of the modified carbons were also studied by argon adsorption at 87.29 K. As results, it was observed that both HN03 and HCI treatments could increase the surface acidity of activated carbons. Activated carbons modified by HCI gave the best performance on the adsorption of methylene blue.Keywords: Activated Carbon, Surface Chemistry, Chemical Treatment, Boehm Titration Method, Adsorption AbstrakKemampuan adsorpsi karbon akti.ftidak hanya ditentukan oleh struktur pori tetapijuga dipengaruhi oleh sifat kimia dari permukaannya. Sifat kimia permukaan karbon aktif dapat secara selektif dimodifikasi dengan tujuan untuk lebih meningkatkan kapasitas adsorpsinya. Pada penelitian ini, karbon aktif NORIT granular ditreatment dengan menggunakan asam oksidator (HNO) dan non-oksidator (HCI) pada berbagai konsentrasi dan suhu. Sifat kimia permukaan karbon aktif dikarakterisasi dengan menggunakan metode titrasi Boehm serta dengan penentuan point of zero charge (pHPZC). Kemampuan adsorpsinya diuji dengan mengadsorp larutan methylene blue, dimana methylene blue merupakan salah satu komponen dalam limbah tekstil. Sedangkan struktur pori karbon aktif dianalisa dengan adsorpsi Ar pada suhu 87,29 K. Penelitian ini menunjukkan bahwa baik treatment dengan HNO3 maupun HCI dapat mengakibatkan terjadinya peningkatan sifat asam pada permukaan karbon aktif. Karbon aktif yang diberi perlalatan dengan HCI memberikan kemampuan adsorpsi yang paling baik dalam adsorpsi larutan methylen biru.Kata Kunci: Karbon Aktif, Sifat Kimia Permukaan, Perlakuan dengan Larutan Kimia, Metode Titrasi Boehm, Adsorpsi

scholarly journals Determination of Point of Zero Charge (PZC) of Concrete Particles Adsorbents

2021 ◽  
Vol 1184 (1) ◽  
pp. 012004
Author(s):  
Ebtehal A. Al-Maliky ◽  
Hatem A. Gzar ◽  
Mohammed G. Al-Azawy
Keyword(s):  
Point Of Zero Charge ◽  
Zero Charge

Surface Chemistry of Mesoporous Materials: Effect of Nanopore Confinement

2002 ◽  
Vol 751 ◽  
Author(s):  
Yifeng Wang ◽  
Charles Bryan ◽  
Huifang Xu ◽  
Huizhen Gao
Keyword(s):  
Surface Chemistry ◽  
Surface Acidity ◽  
Scale Space ◽  
Acid Base ◽  
Acidity Constants ◽  
Solution Interface ◽  
Ion Sorption ◽  
Alumina Particles ◽  
The Difference ◽  
Nanopore Confinement

AbstractAcid-base titration and metal sorption experiments were performed on both mesoporous alumina and alumina particles under various ionic strengths. It has been demonstrated that surface chemistry and ion sorption within nanopores can be significantly modified by a nano-scale space confinement. As the pore size is reduced to a few nanometers, the difference between surface acidity constants (ΔpK = pK2 – pK1) decreases, giving rise to a higher surface charge density on a nanopore surface than that on an unconfined solid-solution interface. The change in surface acidity constants results in a shift of ion sorption edges and enhances ion sorption on that nanopore surfaces.

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