Carboxymethyl starch/montmorillonite composite microparticles: Properties and controlled release of isoproturon.

Preparation of novel high substituted carboxymethyl starch-based microparticles containing sodium montmorillonite (MMT) by crosslinking with Al(3+) was described. For preparing nanocomposite granules carboxymethyl starch (CMS) from native potato starch as well as CMS from amylopectin has been used. The hydrophilic CMS/MMT composite systems were used for herbicide, i.e. isoproturon encapsulation (ca. 75% encapsulation efficiency). The herbicide release rate from CMS/MMT composites in water was significantly reduced when compared to commercial isoproturon: 95% released after ca. 700 h and ca. 24h, respectively. Leaching in soil from composite systems was relatively slower than release in water. After a series of eight irrigations leached about 10% of isoproturon loaded. The CMS/MMT carriers could reduce the potential leaching of herbicide and beneficially reduce pollution of the environment.

Removal of carbamazepine from aqueous solution by adsorption on fly ash-amended soil.

Carbamazepine (CBZ), nonbiodegradable pharmaceutical residue, has become an emerging pollutant in several aquatic environments. The effectiveness of the mixture of soil and fly ash (FA) in adsorbing CBZ from aqueous solution has been studied as well as agitation time, FA content, initial CBZ concentration and desorption as a function of FA content. The adsorption kinetics fits a hyperbolic or pseudo-second-order model. The maximum adsorbed amounts for natural soil and a mixture of soil/FA ranged from 77 to 158 mg kg(-1). Rate constants were considered relatively low (4.15-15.59 × 10(-4) kg mg(-1) min). The logarithmic form of the Freundlich equation gave a linearity and the Kf constants increased with the increase of FA content in adsorbent mixtures and with the affinity between the adsorbent surface and adsorbed solute. The mean removed amounts of CBZ by adsorption batch experiments in a soil mixture with 30% FA content were up to 92.8% for coal FA and 33% in natural soil. This work proved that the mixture of the coal FA and soil can be used as an efficient adsorbent material for removal of CBZ from water.