A simple sulfuric acid pretreatment method to improve the adsorption of Cr(VI) by chitosan

Abstract

An optimum pH of 5.0 for the adsorption of Cr 6ϩ by chitosan was determined by using a stirred-batch reactor method at constant pH. When a column containing chitosan was used to bind Cr 6ϩ in a situation where pH could not be held constant because of pH changes caused by the chitosan itself, significant binding occurred only at solution pH 1 and 2. When chitosan was pretreated with sulfuric acid in a range of 7-70 mol % sulfuric acid : moles glucosamine residue, maximum binding occurred at pH 6.0. Under these conditions, a column containing 0.500 g acidtreated chitosan (35% mole ratio) reduced the concentration of Cr 6ϩ in 713 bed volumes of 25 ppm Cr 6ϩ solution to Յ5 ppm in the effluent. A similar column of pretreated chitosan reduced Cr 6ϩ concentration in 1042 bed volumes of industrial chromium plating rinse water initially containing 18 ppm Cr 6ϩ to Յ5 ppm. Capacity experiment results indicated 60 mg chromium bound per gram of treated chitosan at pH 6.0. Commercial resin IRA-67 was also investigated as a Cr 6ϩ binding agent.

Microwave preparation and copper ions adsorption properties of crosslinked chitosan/ZSM molecular sieve composites

“…[1][2][3] Copper, in particular, is extensively utilized in the electrical plants, and in the manufacture of fungicides and antifouling paints. It could cause harmful, acute and even fatal effect when Copper ions are ingested at high concentration.…”

“…As a result of today's widely industrialized society, heavy metal contamination of various water resources is becoming of great concern because of the toxic effect to human beings and other animals and plants in the environment. [1][2][3] Copper, in particular, is extensively utilized in the electrical plants, and in the manufacture of fungicides and antifouling paints. It could cause harmful, acute and even fatal effect when Copper ions are ingested at high concentration.…”

Preparation and application of alumina/chitosan biocomposite

“…The band at 2921/cm indicates the -CH stretching vibration in -CH and -CH 2 . A band at 1639/cm corresponds to -NH bending vibration in -NH 2 and 1065/cm indicates the presence of -CO stretching vibration in -COH [33]. The bands observed between 1000 and 500/cm could be the characteristic vibrations of aluminium oxide [34].…”

Preparation of biomimetic‐bone materials and their application to the removal of heavy metals

“…It can be seen from Table 6 that all the amino-containing resins remove Cr(VI) under near-neutral conditions. Chitosan is an effective agent for the removal of Cr(VI) in acidic conditions, 32 but under near-neutral condition it is not very effective. The mechanism for the removal of Cr(VI) by the amino-containing resins will be discussed in a later section.…”