Evaluation of NH 4 + Adsorption Capacity in Water of Coffee Husk-Derived Biochar at Different Pyrolysis Temperatures

Ammonium NH 4 + is a pollutant that can be harmful to the water environment. The purpose of this study is to access NH 4 + removal capacity from water by coffee husk-derived biochar. The properties of biochar prepared at different temperatures (300, 450, and 600°C) were determined including TOC, and pH , pH pzc , functional groups of H+/OH−, cation-exchange capacity (CEC), and the characteristics of groups of organic matter (FT-IR spectrum) were identified and evaluated. The trend of NH 4 + adsorption equilibrium and kinetics of biochar have been studied. The experimental design of adsorption equilibrium was carried out by exposing biochar to a NH 4 + solution at different concentrations, ranging from 0 to 50 mg NH 4 + / L for 12 hours. Kinetic surveys were carried out when biochar was exposed to a solution containing 8.3 mg NH 4 + / L for a varying length of time. The results showed that Langmuir and Freundlich models and the pseudo-second-order kinetic model are suitable to explain the NH 4 + adsorption equilibrium and kinetics on the biochar forms derived from coffee husk. Biochar derived from coffee husk prepared at lower pyrolysis temperature has a higher adsorption capacity. The results suggest that the biochar could be used as an adsorbent ammonium from water.

SYNTHESIS OF ZEOLITE-ACTIVATED CARBON COMPOSITE FOR REMOVAL OF AMMONIUM FROM AQUEOUS SOLUTION

In this study, zeolite-activated carbon composite (Z/AC) was synthesized by hydrothermal reaction using kaolin as a source of silica and alumina. The synthesized materials were characterized by Brunner-Emmet-Teller (BET) surface area to calculate surface area, X-ray diffraction (XRD) to study the crystal structure of materials, Infrared spectroscopy (IR) to indicate the presence of functional groups on the surface and scanning electron microscopy (SEM) to determine the morphology of the composites. In this paper, adsorption equilibrium and kinetics for the removal of ammonium by prepared Z/AC materials were evaluated.

The zero length column technique to measure adsorption equilibrium and kinetics: lessons learnt from 30 years of experience

The zero length column technique has been developed over the past 30 years as a versatile experimental method to measure adsorption equilibrium and kinetics. In this review we discuss in detail the theory that forms the basis for the technique in order to understand how to design and operate efficiently a system. Experimental checks that should be performed to ensure the correct interpretation of the dynamic response are presented and examples are used to identify how to avoid major errors in determining diffusion time constants. The review concludes with an overview of all experimental studies available in the literature to date and a set of recommendations that should help improve the standard in the reported equilibrium and kinetic properties.

Mesocellular Silica Foams (MCFs) with Tunable Pore Size as a Support for Lysozyme Immobilization: Adsorption Equilibrium and Kinetics, Biocomposite Properties

The effect of the porous structure of mesocellular silica foams (MCFs) on the lysozyme (LYS) adsorption capacity, as well as the rate, was studied to design the effective sorbent for potential applications as the carriers of biomolecules. The structural (N2 adsorption/desorption isotherms), textural (SEM, TEM), acid-base (potentiometric titration), adsorption properties, and thermal characteristics of the obtained lysozyme/silica composites were studied. The protein adsorption equilibrium and kinetics showed significant dependence on silica pore size. For instance, LYS adsorption uptake on MCF-6.4 support (pore diameter 6.4 nm) was about 0.29 g/g. The equilibrium loading amount of LYS on MCF-14.5 material (pore size 14.5 nm) increased to 0.55 g/g. However, when the pore diameter was larger than 14.5 nm, the LYS adsorption value systematically decreased with increasing pore size (e.g., for MCF-30.1 was only 0.27 g/g). The electrostatic attractive interactions between the positively charged lysozyme (at pH = 7.4) and the negatively charged silica played a significant role in the immobilization process. The differences in protein adsorption and surface morphology for the biocomposites of various pore sizes were found. The thermal behavior of the studied bio/systems was conducted by TG/DSC/FTIR/MS coupled method. It was found that the thermal degradation of lysozyme/silica composites was a double-stage process in the temperature range 165–420–830 °C.