Jianfeng Ma

Mechanism of adsorption of anionic dye from aqueous solutions onto organobentonite

Organobentonite is suggested as potential super-sorbents for the removal of dyes from wastewater. All kinds of organobentonites are synthesized to adsorb dyes; however, the mechanism of the adsorption is still unclear. In this paper, organobentonites were first modified with hexadecyltrimethylammonium bromide at various amounts to reveal the adsorption mechanism. Subsequently, four kinds of organobentonites were utilized to adsorb acid dyes. Results show that the main mechanism of the adsorption of acid dye is an anionic exchange. The counter-ion bromide in the organobentonite was replaced by the dye anion. The study reveals that the adsorption capacity of organobentonite is affected by the surfactant alkyl chain length. When the longer alkyl chain surfactant was modified, bentonite showed higher adsorption capacity. Specific surface areas had no effect on the adsorption. However, the XRD patterns show that interlamellar distance and lamellar distribution have some effects on the adsorption. High adsorption capacity and low residual concentration were obtained by the organobentonite adsorbents. The revelation of the adsorption mechanism makes it possible to obtain more novel and suitable organobentonite adsorbents for anionic dye removal from wastewater.

Adsorption of Orange II dye from aqueous solutions using phosphoric-acid modified clam shell powder

AbstractIn this study, the clam shell, a waste biomaterial, was modified with phosphoric acid to improve the adsorption amount of Orange II dye. The effects of initial concentration, contact time, and temperature on the adsorption were studied. The equilibrium adsorption data of Orange II on the phosphoric acid-modified clam shell powder (PCSP) were adequately represented by Langmuir isotherm with an adsorption capacity of 1,017.13 mg/g, which is higher than that obtained using raw clam shell powder. Adsorption kinetics followed the pseudo-second-order rate expression. Thermodynamic parameters show that the process is exothermal, feasible, and spontaneous. The effect of temperature inferred that the type of adsorption in the study is a physical adsorption. Therefore, PCSP is an efficient and economical adsorbent for dye removal.

Treatment of Dye Wastewater by Zero Valent Iron Composited Organobentonite

A novel material, zero valent iron composited organobentonite (NZVI-OB), was synthesized to adsorb dye from wastewater and to degrade the dye for avoiding secondary pollution. The crystal structure was characterized with X-ray diffraction (XRD). The effect of initial Orange II concentration and reaction time on the removal of Orange II by the NZVI-OB was studied. And the removal mechanism of Orange II was discussed. The results show that the Orange II can be removed by NZVI-OB efficiently. The maximal adsorption amount is 112.66 mg/g. The iron can effectively degrade the organic compounds after adsorption pollution, the carbon contents of organic pollutions after catalyzed and oxidized by the iron are lowered to the 19% of the original.

Enhancement Effect of CTAB in Dye Wastewater Treatment by Bentonite

. The adsorption capacity of Orange II by Cetyltrimethyl Ammonium Bromide (CTAB)+bentonite mixture system and bentonite were tested and compared. The influence factors on removal rate of Orange II such as surfactant, the pH, the contact time and temperature were studied. The results showed that the presence of cationic surfactant such as CTAB could greatly enhance the removal efficiency compared with the system only bentonite supplied. The results showed that the highest removal rate of Orange II appeared on pH＜3, and when the pH value was from 3 to 5, the removal rate would drop 30%-50%.The effect of reaction temperature on the Orange II removal was then discussed, showed that the removal rate of Orange II descended 5%-10% when the temperature was higher than 25°C.

Adsorption and Catalysis of Orange II from Wastewater by Inorganic-Organic-Bentonite

Inorganic-organic-bentonite was synthesized by modification of bentonite by Hydroxy-iron and surfactant, which could be applied in dye removal by adsorption and catalysis. The removal of acid dye Orange II was studied at various factors such as time and pH of solution. The results showed that the inorganic-organic-bentonite could efficiently remove the dye with efficiency of 96.22%. The maximum adsorption capacity is 76 mg/g. The pH of solution has significant effect on both adsorption and catalysis. When pH was 4, the maximum removal efficiency of adsorption and catalysis were 97.57% and 87.23%, respectively. After degradation, the secondary pollution was diminished and the bentonite could be reused.