Kinetic and equilibrium studies of some heavy metal ions adsorption by agricultural wastes

Other Title(s)

الدراسات الحركية و التوازنية لإمتزاز بعض الفلزات الثقيلة على المخلفات الزراعية

Dissertant

Sharif, Huda Yusuf

Thesis advisor

Sharif, Kafyah Mawlud

University

Salahaddin University-Hawler

Faculty

College of Science

Department

Chemistry Department

University Country

Iraq

Degree

Master

Degree Date

2011

English Abstract

The presence of heavy metals in waste and surface waters is becoming a severe environmental problem.

In the present study, the kinetic and equilibrium study for Cu, Ni and Zn ions removal from synthetic waste water by low cost adsorbents.

The locally present low cost adsorbents used in this study were Rice Husk (RH), Rice Husk Ash (RHA), Sesame seed Husk (Ses) and Sunflower Seed Husk (Sun).

Batch adsorption experiments were done to study the effect of various parameters such as ; the initial concentrations of heavy metals, contact time, adsorbent particle size, adsorbent to sorbent ratio, on the adsorption behavior of the studied adsorbents.

The pseudo-first order, pseudo-second order and Elovich kinetic models were applied to explain our kinetic experimental data for Cu, Ni and Zn ions removal by RH.

Values of pseudo-second order rate constant k were 0.1389, 0.225 and 0.1389 gμg-1min-1for Cu, Ni and Zn ions removal respectively ; this indicates that the adsorption proceeded with almost the same rate.

Data of equilibrium adsorption experiments were analyzed by Langmuir, Freundlich, and Temkin and Dubinin-Radushkevich adsorption isotherm models.

The results from equilibrium adsorption experiments at all conditions were fitted to the applied models in the following order : Freundlich > D-R > Temkin > Langmuir The selectivity sequence and the competitive adsorption of each metal from a mixture of the Cu, Ni and Zn ions revealed that the removal percentage was in the following sequence ; Zn > Cu > Ni.

The selectivity sequence and competitive adsorption from a mixture of the studied ions was attributed to the nature of adsorbents and adsorbents.

The FTIR spectra of RH, SES and Sun before and after adsorption of Cu, Ni and Zn ions were used to determine the frequency change in the functional groups of adsorbents.

FTIR spectra of all three adsorbents before and after adsorption of Cu, Ni and Zn ions showed small changes in the frequencies of functional groups on the studied surface.

Small values of adsorption energies together with FTIR spectra of the studied adsorbents, suggested that the sorption process was dominated by physical forces at all condition and that these forces were more important than ion-exchange and particle diffusion.

Kinetic and equilibrium adsorption data provided information on metal removal and difference in metal removal between various species.

From these results, high Cu, Ni and Zn ions removal is observed by all studied adsorbents in the following order; Sun > Ses > RH.

The highest removal of Cu, Ni and Zn ions are obtained with Sunflower, adsorption capacity for Cu, Ni and Zn removal by sun were 92.5, 95.5 and 99.5 % respectively.

Removal of Cu, Ni and Zn ions by RH, Ses and Sun were subjected to temperature which ranged from 10C° to 45C˚ Adsorption capacity was found to increase with pH, increasing pH up to pH = 6 then remained slightly constant with further increase in pH.

While the values of qe for Cu, Ni and Zn removal were increased with increasing the concentration of foreign ions (Na, Ca and K).

The amounts of Ni ions adsorbed at equilibrium (qe) were higher at low concentrations of Na, Ca and K ions and decreased with increasing their concentrations.

Main Subjects

Chemistry

Topics

• Minerals
• Heavy metals
• Adsorption

No. of Pages

102

Table of Contents

• APA
• MLA
• AMA

Language

English

Data Type

Arab Theses

Record ID

BIM-311067