Biosorption of Heavy Metal Ions to Brown Algae, Macrocystis pyrifera, Kjellmaniella crassiforia, and Undaria pinnatifida

A fundamental study of the application of brown algae to the aqueous-phase separation of toxic heavy metals was carried out. The biosorption characteristics of cadmium and lead ions were determined with brown algae, Macrocystis pyrifera, Kjellmaniella crassiforia, and Undaria pinnatifida. A metal binding model proposed by the authors was used for the description of metal binding data. The results showed that the biosorption of bivalent metal ions to brown algae was due to bivalent binding to carboxylic groups on alginic acid in brown algae

Influence of methylated milk casein flocculant dosage on removal rate of oil droplet removal from o/w in flotation

In previous study, we conducted removal of oil droplets in o/w emulsion by flotation involving addition of methylated milk casein (MeCS) as a flocculant in a batch system and proposed a simple kinetic model to evaluate the removal rate constant, K, which is proportional with two adsorption parameters and one experimental conditional parameter. The formers are adsorption rate constant, ka, of oil droplet and its floc onto bubble surface and the saturated adsorption density, Xs, the latter is the specific surface area per unit column volume, which is expressed as a product, (Sb τ)/V, where Sb, τ, and V are bubble surface production rate, bubble residence time within the column and the treated volume of o/w emulsion. This proportional relationship was verified from flotation experiments at the optimum dosage of MeCS, which was determined by the clarification experiment of flocculation. In this study, especially, the influence of MeCS dosage on the removal kinetics of the flotation and the variation of K was investigated. The result suggested that the flotation efficiency in the case of varying MeCS dosage was mainly controlled by the specific surface area of bubbles and the flocculation condition within the flotation column

Kinetic Study of Metal Biosorption to a Brown Alga, Kjellmaniella Crassiforia

A kinetic study of cadmium and lead biosorption to a brown alga, Kjellmaniella crassiforia, was carried out. The shrinking core model derived by M. Gopala Rao and A. K. Gupta (Chem. Eng. J. 24, 181, 1982) was modified and adapted for description of the rate process of cadmium and lead biosorption to the alga. The biosorption rate process was well described and average apparent diffusion coefficient of about 9×10-6 cm2 s-1 was found for both cadmium and lead ions. The value was 20 to 50 times higher than the apparent diffusion coefficients of cadmium and lead ions in strong-acid resins like Dowex 50W-X8

Adsorption of Lactose Using Anion Exchange Resin by Adding Boric Acid from Milk Whey

Influence of adding boric acid (BA) on the adsorption behavior of lactose onto an anion exchange resin (IRA402) was investigated. By adding BA, the amount adsorbed of lactose onto IRA402 was increased ca. 20 % compared with without adding BA. In the presence of BA, ca. 70% of the adsorbed lactose could desorb from IRA402, while the absorbed lactose hardly desorbed in the absence of BA. Lactose molecular was considered to bind to tertiary amine group on IRA402 by Maillard reaction. The optimum conditions of the dosage of BA and pH were found at the molar ratio of BA to lactose ranging from 1-2, and pH 7-9. The kinetics and equilibrium of lactose adsorption could be explained by Langmuir adsorption model (best model). In the case of real whey solution, phosphate strongly affected the adsorption behavior and could be removed as precipitation from the whey over pH 10. Whey proteins had little effect on lactose adsorption, which was ca. 30% less than that in the model system. Moreover, the kinds of whey proteins and amino acids had little effect on the amount adsorbed. Minerals in the whey may consider to be also responsible for the decreased adsorption in the whey

Effect of soy protein-based flocculant on flocculation and filtration of diatomite and kaolin suspensions

The effect of ethylated soy protein-based bioflocculant (EtSP) as a filter aid reagent was investigated. The efficiency of EtSP as a filter aid was evaluated in terms of the specific cake resistance, α, and was compared with chitosan and polyaluminum chloride (PAC). Diatomite and kaolin were used as model particles. Total filtration resistance, R, decreased with increasing flocculant dosage (wt.%, flocculant/particle) and was almost constant in the range of 1 wt.% or more for both particles. The α value was significantly decreased from 1.01 × 1011 to 9.01 × 1010 m/kg for diatomite and from 5.11 × 1010 to 5.20 × 109 m/kg for kaolin by the addition of EtSP in the case of 1.0 wt.%. The α value for cakes formed by EtSP was much smaller than that formed by chitosan and PAC. In the case of diatomite, in the dose range of 0.5–1.0 wt.%, the α value for cakes formed by EtSP and chitosan was almost the same. However, at the excess dose of 2.0 wt.% over, the α value formed by chitosan abruptly increased. In the case of kaolin, in the dose range of 1.0–2.0 wt.%, the α values of chitosan and PAC were mostly the same, however, these values were larger by ca. nine times than that of EtSP

Adsorption modeling by two sites Langmuir type isotherm for adsorption of bisphenol-A and diethyl phthalate onto activated carbon in single and binary system

Adsorption of bisphenol-A (BPA) and diethyl phthalate (DEP) onto activated carbon has been studied. The experimental adsorption data is reasonably well fitted by a two site Langmuir isotherm model. The estimated two equilibrium adsorption constants were almost the same even though the adsorbates were different. This suggested that the existence of two types of adsorption sites with different equilibrium adsorption constants for strong and weak sites on the present activated carbon surface. The equilibrium adsorption constant of strong site was 130 times larger than that of weak site, and the saturated adsorption density of weak site was 2.6 and 3.6 times larger than that of strong site for BPA and DEP, respectively. In addition, adsorption experiments of the binary system have also been carried out. Based on suggesting two type sites, two models, competitive adsorption or noncompetitive adsorption models, were attempted to apply to the experimental results. Judging from the model consideration, the noncompetitive model could describe well the adsorption isotherm in the binary system. Compared with the single system, in the binary system, the equilibrium adsorption constants were almost the same, but the saturated adsorption densities were 10% to 30% lower than that of the single system

Flocculation of diatomite by methylated egg albumin

A common and inexpensive protein, egg albumin, was applied to the solid-liquid separation or flocculation of diatomite. Egg albumin was methylated in a 0.1 M HCl methyl alcohol solution at room temperature. About 90% of the carboxylic groups of egg albumin could be methylated within 24 h. The adsorption of egg albumin to diatomite at pH6.8 was remarkably enhanced by methylation. The adsorption constant of methylated egg albumin to diatomite at 30°C was about 100-fold larger than that of native egg albumin however the adsorption constant of methylated egg albumin decreased to about one-hundredth with decreasing temperature from 30 to 6°C. The saturated adsorption amount of egg albumin was also increased by the methylation. The flocculating ability of methylated egg albumin was examined with a diatomite suspension at 6 and 30°C in the pH range from pH2 to pH11. The diatomite suspension was effectively flocculated by the addition of small amount of methylated egg albumin (only 0.5-1 wt-% against diatomite) over a wide pH range from pH 3 to pH10

Adsorption of Heavy Metal Ions to Floc-Type Biosorbents

Adsorption of cadmium and lead ions to floc-type biosorbents was reported in this work. Two types of biosorbents containing a marine microalga, Heterosigma akashiwo (Hada) Hada or a purple non-sulfur bacterium, Rhodobacter sphaeroides were prepared. The microorganisms inactivated by steam sterilization were immobilized in casein floc and cross-linked with glutaraldehyde. In the present immobilizing method, we obtained the biosorbents comprising as much as 67% of microorganism on a dry-weight basis. Simple metal binding models were applied to explain the adsorption mechanism of bivalent metal ions to the biosorbents. The results showed that casein acted as both the immobilizing material and the adsorbent material. The adsorption of bivalent metal ions to the biosorbents was due to bidentate binding to the acidic sites on casein and monodentate binding to the acidic sites on microorganisms. The metal binding constants and the binding capacities of microorganisms were scarcely influenced by immobilization

Kinetic Study of Lead Adsorption to Composite Biopolymer Adsorbent

A kinetic study of lead adsorption to composite biopolymer adsorbents was carried out. Spherical and membranous adsorbents containing two kinds of biopolymers, humic acid and alginic acid, were used for lead adsorption in dilute acidic solutions. The shrinking core model derived by Rao and Gupta was applied to describe the rate process of lead adsorption to spherical adsorbents (average radii of 0.12, 0.15, and 0.16 cm). Furthermore, the shrinking core model was modified and adapted for the description of the rate process of lead adsorption to membranous adsorbent (an average thickness of 0.0216 cm). The adsorption rate process for the both cases was well-described and the average apparent lead diffusion coefficients of about 6 × 10-6 and 7 × 10-6 cm2・s-1 were found for the spherical and membranous adsorbents, respectively