The electroflotation process of extracting a mixture of Cu, Zn, Ni, Co, Fe hydroxides from wastewater containing NaNO 3 , NaCl, Na 2 SO 4 , Na 2 CO 3 , Na 3 PO 4 , NH 4 OH has been investigated. It was found that the maximum recovery rates of 97-99% are observed in the pH range from 8 to 11 for NaCl solutions. The electroflotation process is the least effective in Na 3 PO 4 solutions with recovery rates of 10-20%. The cationic surfactant SeptaPAV-SKhV-70 (СептаПАВ-СХВ-70) added to the solution increases the extraction ratio in the presence of phosphates by 40-50%. Low efficiency of the electroflotation process in Na 3 PO 4 is associated with a small particle size (about 20-30 μm) and a ]-potential high negative value, what has an injurious effect on the formation of the flotation complex, negatively charged bubbles (H 2 , O 2 ) and negatively charged particles. The addition of a cationic surface-active substance (SAS) reduces negative potential of the dispersed phase and increases particle sizes. All this contributes to the efficient passing of electroflotation process. Presence of a ligand (ammonia solutions) in the sewage reduces the recovery efficiency by 20-30%, especially for copper ions, which are strong complexing agents. Adding to the solution of small amounts (5 mg/l) of industrial surfactants STMs(a) (СТМх(а)) and Flon-1(c) (Флон-1(к)) at total concentration of hydroxides of 100 mg/l leads to a more efficient passing of the electroflotation process. A process flowsheet for removing suspended matters (a mixture of metal hydroxides) using an electroflotation cell and a microfiltration module is proposed. A model series of electroflotation devices with a capacity of 1-10 m 3 /h was proposed for application of the described technical solutions. The separation time in the devices does not exceed 10 minutes, power inputs is up to 0.6 kW•h per 1 m 3 of the treated wastewater with a recovery rate of 97-99%. The cost of an installation for 10 m 3 /h does not exceed 1.5 million rubles.
The results of experimental studies of the extraction of insoluble aluminum (III) compounds from aqueous solutions in the presence of surfactants of various nature and alkaline earth metal ions (Mg 2+ , Ca 2+ , Ba 2+ ) by the electroflotation method are being explained in this study. A comparative analysis of the influence of these components on the efficiency of electroflotation extraction of aluminum (III) hydroxide is carried out. It was found that the presence in the solution of Mg 2+ , Ca 2+ , Ba 2 + at a concentration of 0.5 g/l decreases the extraction degree of Al(OH)3 by electroflotation from 92% for Mg 2+ to 31, Ca 2+ to 23%, Ba 2+ to 28% during electroflotation 20 min. Introduction to surfactant systems increases the extraction degree of Al(OH)3 64% for Mg 2+ , 93% for Ca 2+ , 95% for Ba 2+ . The high effectiveness of surfactants is associated with adsorption on Al(OH)3 and hydrophobization of the surface precipitation, which leads to an increase in the degree of electroflotation extraction of the dispersed phase.
The features of electroflotation extraction of a mixture of heavy hydroxides and non-ferrous metals (Fe 2+ , Ni 2+ , Zn 2+ , Co 2+ , Cu 2+ ) from a five-component system in the presence of various background electrolytes were studied. The influence of the nature of various background electrolytes on the kinetics of electroflotation extraction of the mixture of the studied hydroxides at pH=10 was established. It is shown that the addition of NaCl electrolyte can increase the efficiency and stabilize the electroflotation process of extraction of hard-todissolve heavy and non-ferrous metal compounds as part of multi-component systems from the wastewater of various electroplating plants, the recovery rate can reach to 99%.
Представлен анализ электрофлотационного извлечения смеси ионов меди и цинка из растворов, приготовленных смешением исходных растворов сульфата меди и гидроксида аммония. Показано, что извлечение ионов меди из аммиакатных систем протекает недостаточно эффективно в широком диапазоне pH. Установлено, что при увеличении концентрации аммония, в несколько раз превышающей содержание меди, остаточная концентрация меди после электрофлотации увеличивается до 5 -10 мг/л. Отмечено отрицательное влияние аммиачной среды на скорость электрофлотационного процесса и степень очистки. Показано влияние лиганда NH3 на снижение размера частицы в 8 -10 раз по сравнению с раствором Na2SO4. Установлено, что введение в систему с комплексообразователем (Cu, Zn) катионного ПАВ приводит к смещению ξ-потенциала в положительную сторону. При 10-кратном избытке лиганда по отношению к комплексообразователям катионов Cu, Zn степень электрофлотационного извлечения смеси труднорастворимых соединений меди и цинка снижается. Введение катионного флокулянта Zetag-8160 существенно интенсифицирует процесс электрофлотации (в 2 -3 раза). Показано положительное влияние на процесс фильтрационного извлечения смеси труднорастворимых соединений меди и цинка присутствие в системе катионного ПАВ и флокулянта. Установлено, что в присутствии в системе 10-кратного избытка лиганда (NH3), процесс электрофлотационного извлечения дисперсной фазы гидроксидов меди и цинка протекает наиболее эффективно с катионным флокулянтомZetag-8160, достигая высоких степеней извлечения.
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