Sorption Of Chromium Ions Research Articles

PROMISING MULTIFUNCTIONAL ANIONITES FOR THE EXTRACTION OF CHROMIUM (VI) IONS

30% of the chromium ore reserves in the world are concentrated in Kazakhstan, during the processing of which large volumes of wastewater containing toxic chromium salts, are formed. Сhromium is one of the priority components both in terms of emission and toxicity (for Cr(VI), the maximum permissible concentration is 0.05 mg/l). The compounds of chromium (III) and especially chromium (VI) have a general toxic, allergenic, carcinogenic, mutagenic effect on the human body, and are among the most dangerous pollutants for the environment. The aim of this work is to develop a technological scheme for the extraction of Cr (VI) ions by multifunctional ion exchangers. Methods. Anionite, based on diglycidyl ether of dioxyphenylpropane, allylglycidyl ether and polyethylenimine – Ionite No. 1 has been synthesized by polycondensation, and epoxyamine has been synthesized from benzylamine and epichlorohydrin, by the condensation of which Ionite No.2 has been obtained with polyethylenimine. The sorption of chromium ions on newly synthesized anionites has been studied, using model solutions with the concentrations of 25, 50, 75 and 100 mg/l Cr (VI). Results and discussion. It has been established that Ionite No.1 exhibits greater affinity for Cr (VI) ions. So, its maximum sorption capacity is 13.5, and that of Ionite No.2 is 11.7 mg/g. Conclusion. We have proposed a basic technological scheme of a desalination plant, consisting of modular units: reagent-mechanical, sorption, membrane, ion exchange and bacterial purification. It has been established that reagentmechanical purification is the initial stage of water treatment, designed to isolate insoluble coarse- and fine-dispersed impurities.

Performance evaluation of saponin over other organic acid and tap water for removal of chromium in tannery sludge by electrokinetic enhancement

ABSTRACTThe performance of Saponin over different electrolyte-mediated electrokinetic (EK) process for removal of Cr(III) from tannery sludge was assessed. Saponin exhibited maximum Cr(III) removal efficiency, i.e. 67.6–80.75% as compared to other groups of processing fluids. The possible mechanistic approach for the highest removal efficiency of saponin over other electrolytes may be attributed to synchronized effect of micelle formation and subsequent complexation and sorption of chromium ions. The highest electroosmotic flow rate of saponin indicated low electroosmotic resistance during EK process, which validates the observed trend. Therefore, saponin can be considered as a promising electrolyte for EK treatment of tannery sludge.Abbreviation: CA: Citric acid; LA: lactic acid; OA: oxalic acid; BOD: biochemical oxygen demand; COD: chemical oxygen demand; EK: electokinetic.

Sorption of Chromium Ions from Aqueous Solution onto Chemically Activated Carbons Developed from Maize Cobs

Chemically activated carbons were prepared from maize cobs, using phosphoric acid of variable concentration. The textural parameters of the activated carbons were determined from the nitrogen adsorption isotherms measured at 77 K. The chemistry of the carbon surface was determined by measuring the surface pH, the pHPZC and the concentration of the carbon - oxygen groups of the acid type on the carbon surface. Kinetics of Cr(VI) sorption/reduction was investigated at 303 K. Two processes were investigated in terms of kinetics and equilibrium namely; Cr(VI) removal and chromium sorption were studied at various initial pH (1-7). Removal of Cr(VI) shows a maximum at pH 2.5. At pH<2.5, sorption decreases because of the proton competition with evolved Cr(III) for ion exchange sites. The decrease of sorption at pH>2.5 is due to proton insufficiency and to the decrease of the extent of Cr(VI) reduction. The chemistry of the surface of activated carbon is an important factor in determining its adsorption capacity from aqueous solutions particularly when the sorption process involves ion exchange.

Kinetics of Chromium Sorption on Biomass Fungi from Aqueous Solution

The kinetics of chromium ions sorption from aqueous solution on fungi biomass have been investigated in a batch system. The experimental data were analysed based on an intraparticle diffusion equation and a pseudo-second-order mechanism, in order to predict the constant rate of sorption and the equilibrium capacity with the effect of initial chromium ions concentration, temperature and initial solution pH. The results indicate that the sorption mechanism is described by a pseudo-second order equation. Intraparticule diffusion was signifiant in the lower concentration systems. The sorption of chromium onto the biomass fungi sorbent is favoured at higher concentrations of chromium solution, low temperatures. An activation energy of sorption was evaluted as 11.7 Kj.mol-1 for the sorption of chromium ions on fungi biomass. The results show that the sorption of the chromium ions on fungi biomass is exothermic nature process.