a b s t r a c tA divinylbenzene cross-linked polystyrene resin with amine functional groups (Purolite A170) was grafted with glycidol and characterized as a novel sorbent, GLY-resin, for the oxoborate removal from model solutions and post-crystallization lye. The sorption behavior of GLYresin was investigated using a batch system. The results showed that the sorption was maximal at pH¼ 9.5. The equilibrium was achieved after 24 h. Calculations based on Langmuir model show the monolayer sorption capacity q m ¼1.3 mg/g and the fitted experimental data chemisorption as a dominating mechanism of boron sorption on GLYresin. Boron removal from the solution containing 5 mg B/L and postcrystallization lye having a 9.1 mg B/L was 99% and 80% respectively. The thermodynamic calculations indicated the spontaneous and endothermic nature of the sorption process. The pseudo-secondorder model adequately described the boron sorption on GLY-resin. SorptionÀ desorption efficiency was 100%, which means the boron sorption at next cycle did not decrease.

A new adsorbent based on natural clinoptilolite and amorphous zirconium dioxide (ZrO2) was prepared for the uptake of boron from fresh water. The sorption behaviour of this adsorbent for boron was investigated using a batch system and found to obey Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherm models. The ZrO2 loading level, pH, temperature, contact time, initial boron concentration and adsorbent dose, on the removal of boron were studied. It was found that the removal of boron increased while the adsorbent dose increased and the temperature decreased at an optimum pH (pH = 8) and a contact time of 30 min. At optimum conditions, the maximum boron percentage removal was 75%. According to the D-R model, the maximum capacity was estimated to be > 3 mg B/g of the adsorbent. The adsorption energy value (calculated as 9.13 kJ/mol) indicated that the adsorption of boron on clinoptilolite modified with ZrO2 was physical in nature. The parameters of the adsorption models and the pH investigations pointed to the possibility of a chemisorption process. The thermodynamic parameters (standard entropy deltaS degrees, enthalpy deltaH degrees , and free energy deltaG degrees changes) of boron adsorption were also calculated. The negative value of deltaS degrees indicated a decreased randomness at the solid-solution interface during the boron adsorption. Negative values of deltaH degrees showed the exothermic nature of the process. The negative values of deltaG degrees implied that the adsorption of boron on clinoptilolite modified with amorphous ZrO2 at 25 degrees C was spontaneous. It was considered that boron dissolved in water had been adsorbed both physically and chemically on clinoptilolite modified with 30% ZrO2.

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This paper presents composting of the organic fraction of municipal solid waste containing 50,000 mg/kg of cellucotton and 7980 mg/kg of zinc carried out under laboratory conditions. In the initial material as well as the compost obtained, zinc, cadmium, copper, nickel, and lead were analyzed, and their forms were determined by means of sequential extraction. It was found that 65% of zinc occurs in the organically bound form. Removal of zinc from the waste through leaching and subsequent electrochemical separation from the leaching solution was also examined. A double extraction of the waste with sodium diphosphate(V) enables a reduction of zinc content to 1240 mg/kg. As a result of electrolysis of the leaching solution, 90.2% of Zn is separated on the cathode. This paper suggests a method for processing municipal solid waste with high zinc content based on extraction of the waste with sodium diphosphate(V) and composting. The leaching solution is recovered electrochemically.