Extraction of scandium from red mud by modified activated carbon and kinetics study

Activated carbon （AC） was modified by tri-butyl phosphate （TBP） for selectively extracting scandium from red mud and characterized by BET （Brunauer-Emmett-Teller） surface area. The modified AC had a preferential adsorption to scandium. The influences of adsorbent dos- age, adsorption temperature, and time on adsorption capacity and selectivity to scandium were examined. An optimum adsorbent dosage （-6.25 g/L）, adsorption temperature （308 K）, and adsorption time （40 min） were figured out. A pseudo-second-order kinetics model was employed for describing the adsorption process of scandium.

Study on Adsorption of Formaldehyde by Modified Activated Carbon

By using potassium permanganate impregnation method,common activated carbon was processed in 0. 079 mol/L KMnO4 solution at 650℃ to obtain modified activated carbon loaded with manganese oxide,and then different quantities of common activated carbon and modified activated carbon were used to adsorb 0. 3 mg/m^3 formaldehyde. The results showed that carbon and manganese atoms on the surface of modified activated carbon could adsorb formaldehyde,and the removal rate of 0. 3 mg/m^3 formaldehyde by 30 g of modified activated carbon reached 80%,increased one time compared with that by common activated carbon. Different amounts of activated carbon had various effects on the adsorption of formaldehyde,and the best usage of common activated carbon and modified activated carbon was 100 and 30 g respectively.

Enhancement of gaseous mercury(Hg^0) adsorption for the modified activated carbons by surface acid oxygen function groups

This article discussed the benzoic acid activated carbons which have changed the types and content of acid oxygen-function groups on the surface of activated carbons and their effect on the adsorption for Hg^0 in simulated flue gas at 140 ℃. These surface acid oxygen function groups were identified by Boehm titration, Fourier transformation infrared spectrum, temperature programmed desorption and X-ray photoelectron spectroscopy. It indicates that the carboxyl, lactone and phenolic were formed when the benzoic acid is loaded on the surface of activated carbons. Among the surface acid oxygen function groups, the carboxyl groups enhance the adsorption capacities of Hg^0 for activated carbons to a greater extent.

Simultaneous removal and oxidation of arsenic from water byδ-MnO 2 modified activated carbon

The ubiquitous arsenic in groundwater poses a great risk to human health due to its environmental toxicity and carcinogenicity.In the present work,a new adsorbent,δ-MnO2 modified activated carbon,was prepared,and its performance for the uptake of arsenate and arsenite species from aqueous solutions was investigated by batch experiments.Various techniques,including FESEM-EDX,p-XRD,XPS and BET surface area analysis,were employed to characterize the properties of the adsorbent and the arsenic adsorption mechanisms.The results showed thatδ-MnO2 covered on the surface and padded in the pores of the activated carbon.Adsorption kinetic studies revealed that approximately 90.1%and 76.8%of As(Ⅲ)and As(V),respectively,were removed by the adsorbent in the first 9 hr,and adsorption achieved equilibrium within 48 hr.The maximum adsorption capacities of As(V)and As(Ⅲ)at pH 4.0 calculated from Langmuir adsorption isotherms were 13.30 and 12.56 mg/g,respectively.The effect of pH on As(Ⅴ)and As(Ⅲ)removal was similar,and the removal efficiency significantly reduced with the increase of solution pH.Arsenite oxidation and adsorption kinetics showed that the As(Ⅴ)concentration in solution due to As(Ⅲ)oxidation and reductive dissolution of MnO2 increased rapidly during the first 12 min,and then gradually decreased.Based on the XPS analysis,nearly 93.3%of As(Ⅲ)had been oxidized to As(V)on the adsorbent surface and around 38.9%of Mn(Ⅳ)had been reduced to Mn(Ⅱ)after As(Ⅲ)adsorption.This approach provides a possible method for the purification of arsenic-contaminated groundwater.

Adsorption of Chromium （VI） onto Activated Carbon Modified with KMnO4

The adsorption capacity of activated carbon modified with KMnO4 （potassium permanganate） for Cr（VI） from aqueous solution was investigated. The modified activated carbon was characterized by SEM （scanning electron microscopy）, FT-IR （Fourier transform infrared spectrometer）, and N2 adsorption/desorption tests. Adsorption of Cr（VI） from aqueous solution onto the activated carbon was investigated in a batch system. In the present study, the effect of various parameters such as pH, contact time and initial concentration on the adsorption capacity were determined by ICP-AES （inductively coupled plasma atomic emission spectrometry）. The Cr（VI） adsorption on the activated carbon conforms to the Langmuir and Freundlich isothermal adsorption equation. The rates of adsorption were found to conform to pseudo-second order kinetic. The modified activated carbon can be an effective adsorbent for Cr（VI） from the aqueous solution.