ВПЛИВ ГІДРАТАЦІЇ НА ОСНОВНО-КИСЛОТНІ ВЛАСТИВОСТІ ОКСИДІВ ЕЛЕМЕНТІВ

Various definitions (by Brǿnsted – Lauri , Lux – Flood, Lewis )of the basicity – acidity for the systems of different types have been regarded. The necessity and possibility of the establishment of a general approach to definition of the mentioned parameter for binary demonstrated. A general character of the effect of hydration of basic and acidic oxides on the interrelation of their basic-acidic properties by Lux – Flood is established. As a parameter which reflects the expression of acidic properties, a value of the effective electronegativity of oxides and hydroxides of elements is proposed. The electronegativity of 3.0 for SO3 is chosen as principal one and values of other oxides were calculated from thermochemical data for sulfates of appropriate elements in analogous to L. Pauling manner for elements. Its values are 2.2-3.1 for acidic oxides, 0.3-1.6 for basic oxides and 1.7-2.1 for amphoteric oxides. Water is known as amphoteric oxide able to react both with acid and with basic oxides. The prevalence of acidic properties over basic ones for water is shown. It is caused by difference in energetic balance of the processes of accession to and removal from the H2O molecule of O2− ions. During the processes of hydration in the series oxide – hydroxide – hydroxide hydrate – aqueous solution a decrease of electronegativity in a case of acidic oxides and its increase in a case of basic oxides are observed. It has been shown equalizing (for basic-acidic differences) role of water concerning oxides of elements. A correlation between electronegativity of oxides and hydroxides of elements and basicity and acidity of their aqueous solution is established.Розглянуто різні визначення(за Брьонстедом – Лоурі,Луксом – Флудом, Льюісом) основності –кислотності для систем різного типу. Показано потребу й можливість встановлення загального підходу щодо визначення зазначеного параметру для бінарних сполук типу оксидів та гідроксидів(основ та кислот) елементів. Встановлено загальний характер впливу гідратації оксидів елементів на співвідношення їхніх основно-кислотних властивостей за Луксом-Флудом. Як параметр, що відображає рівень кислотних властивостей, запропоновано застосовувати величину ефективної електронегативності, розраховуваної за методом, аналогічним до методу Л. Полінга щодо елементів. За базову величину прийнято значення електронегативності 3.0 для SO3, а для решти оксидів її значення було розраховано з термохімічних даних для сульфатів відповідних елементів. Її значення становлять 2.2-3.1 для кислотних оксидів, 0.3-1.6 для основних оксидів та 1.7-2.1 для амфотерних оксидів. Вода є відомою як амфотерний оксид, здатний до взаємодії як з кислотними, так і з основними оксидами. Уперше показано і обґрунтовано деяке перевершення кислотних властивостей води над основними, що викликано різницею енергетичних балансів процесів приєднання до молекул H2O та відняття від них йонів O2−. Встановлено факт поступового зниження електронегативності у ряді кислотний оксид – кислота – гідрат кислоти – водний розчин та її зростання у ряді основний оксид – гідроксид – гідрат гідроксиду – водний розчин у процесі гідратації. Таким чином, вода відіграє вирівнювальну роль щодо основно-кислотних властивостей оксидів елементів. Встановлено наявність кореляції між електронегативністю оксидів і гідроксидів елементів та константами основності і кислотності їхніх водних розчинів

THE EFFECT OF HYDRATION ON THE BASIC-ACID PROPERTIES OF OXIDES OF ELEMENTS

Various definitions (by Brǿnsted – Lauri , Lux – Flood, Lewis )of the basicity – acidity for the systems of different types have been regarded. The necessity and possibility of the establishment of a general approach to definition of the mentioned parameter for binary demonstrated. A general character of the effect of hydration of basic and acidic oxides on the interrelation of their basic-acidic properties by Lux – Flood is established. As a parameter which reflects the expression of acidic properties, a value of the effective electronegativity of oxides and hydroxides of elements is proposed. The electronegativity of 3.0 for SO3 is chosen as principal one and values of other oxides were calculated from thermochemical data for sulfates of appropriate elements in analogous to L. Pauling manner for elements. Its values are 2.2-3.1 for acidic oxides, 0.3-1.6 for basic oxides and 1.7-2.1 for amphoteric oxides. Water is known as amphoteric oxide able to react both with acid and with basic oxides. The prevalence of acidic properties over basic ones for water is shown. It is caused by difference in energetic balance of the processes of accession to and removal from the H2O molecule of O2− ions. During the processes of hydration in the series oxide – hydroxide – hydroxide hydrate – aqueous solution a decrease of electronegativity in a case of acidic oxides and its increase in a case of basic oxides are observed. It has been shown equalizing (for basic-acidic differences) role of water concerning oxides of elements. A correlation between electronegativity of oxides and hydroxides of elements and basicity and acidity of their aqueous solution is established

ВИЛУЧЕННЯ УРАНУ(УІ) І ТОРІЮ(ІУ) ІЗ ВОДНИХ РОЗЧИНІВ НЕОРГАНІЧНИМИ СОРБЕНТАМИ

Досліджено ефективність використання нового сорбенту на основі силікагелю при вилученні урану(VІ) і торію(IV) із розбавлених водних розчинів. Показано, що досліджуваний сорбент краще поглинає уран(VI) і торій(ІV), ніж відомий сорбент (силікагель). Вивчено вплив часу контакту фаз, рН середовища, природи металу та іонного складу розчину на ефективність процесу сорбції урану(VІ) і торію(IV). Експериментально отримані ізотерми сорбції оброблені за допомогою рівнянь Ленгмюра і Фрейндліха

ОСОБЛИВОСТІ КИСЛОТНО-ОСНОВНИХ ВЛАСТИВОСТЕЙ ОКСИГЕНОВИХ СПОЛУК СИЛІЦІЮ ТА ГЕРМАНІЮ

Peculiarities of the change of acid-basic properties of Silicon and Germanium oxy-compounds as a function of the position of elements in the periodic system are established. It is stated that Germanium dioxide possesses much lower (compared to SiO2 and SnO2) temperatures of melting and boiling as well as lower surface tension and dynamic viscosity. This fact points out more income of the molecular structure, hence, more expressed acidic properties. The higher value of the constant of acidity of the aqueous solution of GeO2 (i.e. H2GeO3) in comparison with H4SiO4 confirms the above mentioned. Systems of the GeO2 – MxOy type, where M – metal, exhibit more chemical diversity compared to the analogous systems on the basics of SiO2. For example, GeO2 forms rather stable ternary compounds with Ga2O3 or CeO2, but SiO2, contrary, does not. At the same time, compounds of SiO2 with P2O5 are much stronger, than analogous compounds of GeO2. This fact means that SiO2 has more basic properties than GeO2. Unfortunately we have no other quasi-binary systems of SiO2 or GeO2 with more acidic oxides for the comparison. The sum of these data indicates on the more expressed acidic and less expressed basic properties of GeO2 versus SiO2, which is an additional confirmation of the “Silicon – Germanium anomaly” in the series of elements of the IV group of the periodic system. This phenomenon, probably, is caused by completion of the previous 3d – electronic level in an atom of Germanium. So, some resemblance between Si–Ge and Al–Ga pairs of elements takes place.Встановлено особливості зміни кислотно-основних властивостей оксигенвмісних сполук Силіцію та Германію у залежності від їхнього положення у періодичній системі. Проведено зіставлення фізико-хімічних властивостей їхніх вищих (SiO2 і GeO2) і нижчих (SiO і GeO) оксидів, а також їх здатності до взаємодії з оксидами елементів (металів і неметалів) переважно основної або кислотної природи

PECULIARITIES OF ACID-BASIC PROPERTIES OF SILICON AND GERMANIUM OXY-COMPOUNDS

Peculiarities of the change of acid-basic properties of Silicon and Germanium oxy-compounds as a function of the position of elements in the periodic system are established. It is stated that Germanium dioxide possesses much lower (compared to SiO2 and SnO2) temperatures of melting and boiling as well as lower surface tension and dynamic viscosity. This fact points out more income of the molecular structure, hence, more expressed acidic properties. The higher value of the constant of acidity of the aqueous solution of GeO2 (i.e. H2GeO3) in comparison with H4SiO4 confirms the above mentioned. Systems of the GeO2 – MxOy type, where M – metal, exhibit more chemical diversity compared to the analogous systems on the basics of SiO2. For example, GeO2 forms rather stable ternary compounds with Ga2O3 or CeO2, but SiO2, contrary, does not. At the same time, compounds of SiO2 with P2O5 are much stronger, than analogous compounds of GeO2. This fact means that SiO2 has more basic properties than GeO2. Unfortunately we have no other quasi-binary systems of SiO2 or GeO2 with more acidic oxides for the comparison. The sum of these data indicates on the more expressed acidic and less expressed basic properties of GeO2 versus SiO2, which is an additional confirmation of the “Silicon – Germanium anomaly” in the series of elements of the IV group of the periodic system. This phenomenon, probably, is caused by completion of the previous 3d – electronic level in an atom of Germanium. So, some resemblance between Si–Ge and Al–Ga pairs of elements takes place

COLLOIDAL- AND CHEMICAL CONSISTENCIES OF FLOTATION-WITH-CARRIER WATER CLEANING FROM CHROME VI IONS

Size-consist and electrokinetic effects in heterogenic system generated by flotation-with-carrier water cleaning from Cr (VI) ions experimentally researched. Based on fundamental principles of DLVO Theory ascertained that effectiveness of flotation cleaning is determining by molecular attraction (Um) and electrostatic repulsion (Ui) forces balance between dispersion phase particles of test system. Approved that water can be definitely (98%) purified from Cr (VI) oxoanions (CrО42-) by flotation-with-carrier, which are previously precipitated with over equivalent amount of barium chloride (1.25 mole ВаCl2/ 1 mole К2CrО4) using as carrier a fine-dispersed paraffin (paraffin consumption is 6.31g/ 1 g BaCrO4). Determined that belaying of positive paraffin particles onto bubbles simplified by their negative charge. Total interaction energy (U = Um + Ui) between sublat particles (paraffin and barium chloride particle aggregate) and air bubbles is equal to zero upon optimal carrier consumption conditions. This points to the predominance of intermolecular attraction forces between converging particles of dispersion phase, which leads to their enlargement and as a consequence to more solid belaying onto air-bubbles surface and treated solution surface. Considering that electrolyte concentration with interaction energy hump between spherical particles is on the X-line (U = 0) and is critical, in other words causes quick disperse system coagulation; and the condition k∙Нс ≈ 2 must be met (where Нс is critical distance between particles). Computation of Нс value were performed for test flotation system: κ ∙Нс = 1,05∙106 cm-1 × 1,89∙10-6 cm = 1,99. Obtained result can lend evidence that in conditions of equal amounts of precipitator and chrome oxo anions, and optimal carrier consumption, each sublat particles collision with bubbles will lead__to heterocoagulation. Under precipitator consumption less than 1 mole ВаCl2/ 1 mole К2CrО4 Cr(VI) recovery ratio is not exceed 40%. In that case sublat and air bubbles interaction carries in sufficiently deep (-(40-50) kT) distal potential minimum. In such conditions remains the film of dispersion medium between bubble and particle, which promotes the detachment action forces of sublat particles from floating bubbles surface. Moreover in case of low precipitator consumption there is some excess amount of carrier particles which are not linked with extracted ion. In accordance with mentioned carrier particles will be extracted primarily. Under highest than optimal precipitator consumption the potential of sublat particles raising is observed, and as consequence the ion-electrostatic barrier of repulsion (Ui=10-20 kT) between them is observed. There is water layer between sublat particles remains in such conditions. This is showed by deep (over 100 kT) potential minimums on the curves. As a result on the solution surface there is crumbly coagulum visually observed, which is destroyed by floating bubbles and carried into treated solution volume due to air agitation

COLLOID-HYDRODYNAMIC REGULATIONS OF THE FLOTATION CHROM (IV) WITH VIOLATION

This paper presents theoretical and experimental studies of the regularities of colloid-hydrodynamic interactions of small particles and a collectively rising air bubble in a model and real system using finely dispersed paraffin as a carrier of BaCrO4 particles. Theoretical studies of the regularities of hydrodynamic interactions of a collectively popping bubble (with a radius of 295 μm) with small particles (with a radius of 3.2 to 12.8 μm) have been carried out. The values of dimensionless criteria were determined with the help of which the efficiency of collision of particles (taking into account their inertia) and the bubble of air rising in water in the transient hydrodynamic regime (Re = 57) was estimated. As a result of theoretical studies of the model of the flotation system, regularities of long-range and near-field hydrodynamic interaction of particles and a bubble are established, which show that the mechanism of such interactions depends on the radius of the particle and its density. It was found that particles with a small radius (from 3.2 μm) and a relatively high density (from 4.5 g/cm3) collide with the bubble surface (as a result of the predominance of inertial forces in the hydrodynamic interaction mechanism) above its equator. In this region, which is unfavorable for fixing particles on the bubble surface, relatively large particles whose density is smaller than the density of the medium also collide, and the radius exceeds 10.9 μm, which is due to the prevalence of viscous drag forces of the medium.It is shown that the extreme nature of the hydrodynamic interactions of particles with a bubble allows us to theoretically justify the optimum amount of carrier for the flotation of small particles. Thus, for example, calculations showed that for flotation of chromium (VI) using finely dispersed paraffin as a carrier, the optimal amount of paraffin corresponds to 7.2 g/g BaCrO4. The experimental values of the capture efficiency of particles by air bubbles, characterizing the joint effect of both hydrodynamic and inertial forces, as well as molecular, electrostatic and other interaction forces arising as a result of surface phenomena in similar colloidal systems are determined. At optimal paraffin consumption (6.3 g/g BaCrO4), the capture efficiency was 1.3×10-3, and the relative capture efficiency (calculated as the ratio of this value to the capture efficiency in the collision without taking into account the hydrodynamic interaction of the particle with the bubble) is 1.8×10-2. The obtained experimental values of capture efficiency agree with the data of the researchers who studied the flotation of small particles without the use of flotation reagents. It has been experimentally established that when about 4.0 g/g of BaCrO4 carrier is added to the system, then chromium(VI) is not flotated at all. A carrier that exceeds the optimum amount somewhat reduces the efficiency of chromium(VI) flotation. Theoretical and experimental data obtained in this paper are in good agreement

ЗАКОНОМІРНОСТІ ВИЛУЧЕННЯ ІОНОГЕННИХ І НЕІОНОГЕННИХ (ТВІНИ) ПАР З ЇХ БІНАРНИХ ВОДНИХ РОЗЧИНІВ

Dodecylpyridinium chloride and nonionic surfactants – Twins (Tween-20, Tween-40, Tween-80) from their binary equimolar aqueous solutions under conditions of varying the acidity of the medium from 2 to 12 have been experimentally studied. Possible mechanisms for the interaction of surfactants of various types in a wide range of pH values of the mediumare proposed. Studies have shown that Twins are not sensitive to a change in the acidity of the medium, their extraction from binary solutions with sodium dodecyl sulfate and Dodecylpyridinium chloride increases over the entire pH range of the medium and reaches 92-98%. Dodecylpyridinium chloride is best extracted from binary aqueous solutions with Twins in strong acid (pH 2) and strong alkaline (pH 12) media. In a wide range of pH values of the medium, the degree of flotation extraction of sodium dodecyl sulfate from binary solutions is increased by about 15% as compared to its extraction from an individual solution.The maximum of flotation extraction of sodium dodecyl sulfate from both individual and equimolar binary aqueous solutions with Twins is observed in acidic (pH 7) and alkaline (pH 7-10) media. The coefficient of flotation separation for binary solutions of Tween-sodium dodecyl sulfate is calculated, it which shows exactly how the surfactant is enriched with afoam fraction at a certain pH value. The formal study of the kinetics of flotation extraction of surfactants allowed to calculate the rate constant of the process and to establish the optimal flotation time. The time required for the maximum extraction of Twins and sodium dodecyl sulfate from the binary solution has reduced in comparison with individual solutions and itis about 2-3 minutes, and for extraction of Twins and Dodecylpyridinium chloride from their binary solution it is 5-7 minutes. The values of the rate constants of flotation are increased by 2-5 times for Twins, 3,5-5 times for sodium dodecyl sulfate when they are extracted from binary solutions of Tween- sodium dodecyl sulfate as compared to extraction from individualsolutions; ≈ 1,5 – 3 times for Twins and 1,5 – 3 times for Dodecylpyridinium chloride when they are extracted from binary solutions of Twin – Dodecylpyridinium chloride. The obtained results can be used in the selection of optimal technological parameters for flotation of ionicand non-ionic surfactants.Вивчені закономірності флотаційного вилучення іоногенних і неіоногенних (Твіни) поверхнево-активних речовин (ПАР) з їх індивідуальних і бінарних водних розчинів. Показано, що Твіни доцільно вилучати з водних розчинів методом пінного фракціонування у всьому інтервалі значень рН середовища, катіонні та аніонні ПАР – в кислому та лужному середовищі, при концентрації розчинів, яка не перевищує 100 мг/дм3. Змінюючизначення рН розчину, що містять Твіни і ДДСН, Твіни і ХДДП можна досягти переважного вилучення одного з них. Швидкість вилучення неіоногенних ПАР (Твіни) більша за швидкість вилучення іоногенних ПАР (ДДСН, ХДДП) з індивідуальних та еквімолярних бінарних розчинів

КОЛОЇДНО-ГІДРОДИНАМІЧНІ ЗАКОНОМІРНОСТІ ФЛОТАЦІЇ ХРОМУ (VI) З НОСІЄМ

This paper presents theoretical and experimental studies of the regularities of colloid-hydrodynamic interactions of small particles and a collectively rising air bubble in a model and real system using finely dispersed paraffin as a carrier of BaCrO4 particles. Theoretical studies of the regularities of hydrodynamic interactions of a collectively popping bubble (with a radius of 295 μm) with small particles (with a radius of 3.2 to 12.8 μm) have been carried out. The values of dimensionless criteria were determined with the help of which the efficiency of collision of particles (taking into account their inertia) and the bubble of air rising in water in the transient hydrodynamic regime (Re = 57) was estimated. As a result of theoretical studies of the model of the flotation system, regularities of long-range and near-field hydrodynamic interaction of particles and a bubble are established, which show that the mechanism of such interactions depends on the radius of the particle and its density. It was found that particles with a small radius (from 3.2 μm) and a relatively high density (from 4.5 g/cm3) collide with the bubble surface (as a result of the predominance of inertial forces in the hydrodynamic interaction mechanism) above its equator. In this region, which is unfavorable for fixing particles on the bubble surface, relatively large particles whose density is smaller than the density of the medium also collide, and the radius exceeds 10.9 μm, which is due to the prevalence of viscous drag forces of the medium.It is shown that the extreme nature of the hydrodynamic interactions of particles with a bubble allows us to theoretically justify the optimum amount of carrier for the flotation of small particles. Thus, for example, calculations showed that for flotation of chromium (VI) using finely dispersed paraffin as a carrier, the optimal amount of paraffin corresponds to 7.2 g/g BaCrO4. The experimental values of the capture efficiency of particles by air bubbles, characterizing the joint effect of both hydrodynamic and inertial forces, as well as molecular, electrostatic and other interaction forces arising as a result of surface phenomena in similar colloidal systems are determined. At optimal paraffin consumption (6.3 g/g BaCrO4), the capture efficiency was 1.3×10-3, and the relative capture efficiency (calculated as the ratio of this value to the capture efficiency in the collision without taking into account the hydrodynamic interaction of the particle with the bubble) is 1.8×10-2. The obtained experimental values of capture efficiency agree with the data of the researchers who studied the flotation of small particles without the use of flotation reagents. It has been experimentally established that when about 4.0 g/g of BaCrO4 carrier is added to the system, then chromium(VI) is not flotated at all. A carrier that exceeds the optimum amount somewhat reduces the efficiency of chromium(VI) flotation. Theoretical and experimental data obtained in this paper are in good agreement.У роботі представлені теоретичні та експериментальні дослідження закономірностей колоїдно-гідродинамічних взаємодій малої частинки та колективно спливаючої повітряної бульбашки в модельній та реальній системі з використанням тонкодиспергованого парафіну, як носія частинок BaCrO4. Проведено теоретичні дослідження закономірностей гідродинамічної взаємодії малої частинки (радіусом від 3,2 до 12,8 мкм) з бульбашкою (радіусом 295 мкм), яка спливає в колективі аналогічних бульбашок. Визначено значення безрозмірних критеріїв, які запропоновані авторами кінетичної теорії флотації для оцінки ефективності зіткнення частинки (з урахуванням її інерції) і пухирця повітря, спливаючого в перехідному гідродинамічному режимі (Re = 57). В результаті теоретичних досліджень моделі флотаційної системи встановлені закономірності дальнього і ближнього гідродинамічних взаємодій частинки і бульбашки, які показують, що механізм таких взаємодій залежить від радіусу частинки і її густини. Показано, що екстремальний характер гідродинамічних взаємодій малої частинки з бульбашкою дозволяє теоретично обґрунтувати оптимальну кількість носія для флотації дрібних частинок. Так, наприклад, розрахунки показали, що для флотації хрому(VI) з використанням тонкодисперсного парафіну як носія оптимальна кількість парафіну відповідає 7,2 г/г BaCrO4. Визначено експериментальні значення ефективності захоплення частинок бульбашками повітря, що характеризують спільний вплив як гідродинамічних, так і інерційних сил, а також молекулярні, електростатичні та інші сили взаємодії, що виникають внаслідок поверхневих явищ у подібних колоїдних системах. Отримані експериментальні значення ефективності захоплення співпадають з даними дослідників, які вивчали флотацію малих часток без застосування флотаційних реагентів. Теоретичні та експериментальні дані, отримані в даній роботі, добре узгоджуються між собою

POSSIBILITY OF PHYTOSORBENT FROM CORN STALKS FOR THE ADSORPTION REMOVAL OF CATIONIC DYES

It was obtained phytosorbent from corn stalks and studied its adsorption properties on the example of cationic dyes (methylene blue and crystal violet). It was established that phytosorbent from corn stalks is an effective low-cost adsorbent for the removal of cationic dyes from their aqueous solutions