Features of the crystallization of AlCl3·6H2O in the system AlCl3 – MeClx – HCl – H2O

A laboratory setup has been developed to study the regularities of crystallization of aluminium chloride hexahydrate from hydrochloric acid solutions. The influence of the AlCl3 content in the initial solution, the consumption of gaseous HCl, and the behavior of impurities on the crystallization of AlCl3·6H2O from aluminium chloride solutions of leaching cinder obtained as a result of chlorinating ash burning from thermal power plants in Kazakhstan have been studied. The behavior of impurity metals in the process of crystallization of aluminium chloride solution has been studied, and their distribution between the products of the crystallization process has been established. It is shown that aluminium chloride content in the solution decreases with an increase in the consumption of hydrochloric acid. It was found that under the conditions of crystallization of AlCl3·6H2O, all impurities, except for barium, pass by 98% into the mother liquor. To reduce barium and other impurities in the obtained crystals of AlCl3·6H2O, it is proposed to carry out multiple washing of the crystals with hydrochloric acid (32% HCl). It has been shown that a decrease in the acidity of the washing solution from pH = 10 to pH = 5.5 ensures the isolation of ACH crystals with a minimum content of impurity metals, ppm: 3-5 Ca; 3-6 Fe; 1-3 Mg; 0.1-0.5 Ti; 1-3 Na; 20-30 P2O5. The moisture content of the obtained crystals is 4-5%; the particle size is 400-900 microns. As a result of mathematical processing, regression equations were constructed that adequately predict aluminium chloride content in the solution and its extraction into crystalline hydrate, depending on the consumption of hydrochloric acid. The optimal parameters of the crystallization process have been established: Т = 60 ºС, HCl concentration in the solution - 26-30%, HCl gas consumption = 0.5 l/min, duration 1 hour.

Comparison of flavonoid content and antioxidant activity in calyces of two roselle varieties (Hibiscus sabdariffa L.)

Free radicals can cause various degenerative diseases such as cancer and cardiovascular disease. Flavonoids have antioxidant abilities that inhibit damage from free radicals. The roselle antioxidant mechanism is associated with high flavonoid content. Red and purple roselles are two varieties of roselle (Hibiscus sabdariffa L.) cultivated in Indonesia. The aim of this research was to analyze the differences in flavonoid content and antioxidant activity in the calyces of two varieties of roselle (Hibiscus sabdariffa L.), red and purple. Total flavonoid analysis and antioxidant activity testing were done by spectrophotometry in the visible region. Total flavonoid content was analyzed by pretreatment with aluminium chloride and sodium acetate. Antioxidant activity was tested with 2,2-diphenyl-1-picrylhydrazyl. The total flavonoids for both red and purple roselle calyces ethanolic extract were 27.55 and 39.18 mg quercetin equivalent per gram. The half maximal inhibitory concentration values obtained for both red and purple roselle calyces ethanolic extract a were 51.59 and 42.17 μg/mL. The total flavonoid content and antioxidant activity of purple roselle calyces ethanolic extract was higher and stronger than red roselle calyces ethanolic extract.

Efisiensi Penurunan Kadar COD, TSS, dan TDS pada Air Limbah Industri Pangan menggunakan Koagulan Poly Alumunium Chloride dengan metode Jar Test

Industri pangan menghasilkan air limbah berbahan organik dan padatan tersuspensi maupun terlarut yang tinggi. Salah satu proses pengolahan air limbah yaitu dengan proses koagulasi-flokulasi yang bertujuan untuk menghilangkan padatan tersuspensi dan zat organik yang dapat menyebabkan kekeruhan serta bau dengan penambahan koagulan. Penambahan koagulan pada instalasi pengolahan air limbah (IPAL) tidak dilakukan secara kuantitatif, sehingga perlu dilakukan percobaan dengan metode jar test. Tujuan percobaan untuk mengetahui pH dan dosis optimum serta efisiensi koagulan poly aluminium chloride (PAC) untuk menurunkan kadar chemical oxygen demand (COD), total suspended solid (TSS), dan total dissolved solid (TDS). Hasil uji parameter COD, TSS, dan TDS dibandingkan dengan Surat Keputusan Gubernur Tingkat 1 Jawa Barat (SK Gub TK 1 Jabar) No. 6 Tahun 1999 tentang Baku Mutu Limbah Cair Bagi Kegiatan Industri di Jawa Barat. Berdasarkan hasil percobaan diperoleh kondisi optimum koagulan PAC pada pH air limbah 6–7 dengan dosis koagulan optimum pada (80–90) mg/L. Hasil pengujian parameter TS, TDS, TSS, kekeruhan dan COD berturut-turut memberikan nilai efisiensi sebesar (52,6-57,8)%, (53,9-55,5)%, (52,4-58,1)%, (97,8-99,1)%, dan (71,6–77,1)%. Percobaan yang dilakukan membuktikan bahwa koagulan PAC mampu menurunkan kadar pada parameter uji dengan nilai efisiensi yang cukup besar.

Sustainable Silicon and High Purity Alumina Production from Secondary Silicon and Aluminium Raw Materials through the Innovative SisAl Technology

Calcium aluminate slag produced by the aluminothermic reduction of silica is tested as a candidate raw material for the hydrometallurgical production of pure aluminium chloride hexahydrate (ACH) through leaching with hydrochloric acid. The crystallization of ACH follows by sparging the pregnant liquor with hydrochloric gas. Almost total extraction of Al is achieved with the use of azeotropic HCl acid solution (5.9 M) at 80 °C and 1 h retention time. A pregnant liquor with approximately 20 wt% AlCl3 is produced as a base for ACH crystallization by sparging it with gaseous HCl. The ACH produced is re-dissolved and crystallized three to four times until high purity is achieved. High purity ACH acts as a precursor for producing High Purity Alumina (HPA), a high added value material used in LEDs and lithium-ion batteries and other niche applications.

Effect of clariflocculator and pulsator based sedimentation technology and poly-aluminium chloride coagulant type on the efficiency of the water treatment plant

Polyaluminium chloride (PAC) with different basicity is used as a coagulant in most drinking water treatment plants (WTP). The aluminium concentration in PAC and its hydrolysis mechanism varied with the basicity of PAC. Incremental addition of PAC changes various Physico-chemical properties and turbidity removal mechanisms in water. Water treatment plants use the PAC concentration beyond its optimum dose without considering other aspects, including residual aluminium concentration. In the present work, the effect of high and medium basicity of PAC on different Physico-chemical properties like pH, zeta potential, and residual aluminium concentration of water was investigated. The pH of treated water decreases with the incremental addition of PAC, and an increase in zeta potential and residual aluminium concentration in treated water was evidenced. The change in pH after PAC addition is responsible for deciding the coagulation mechanism and efficiency of the coagulation process. pH reduction is comparatively more in high basicity PAC than medium basicity. PAC hydrolysis mechanism is controlled by the zeta potential of water and can be used as an alternative method to decide the optimum coagulant dose. The performance of clariflocculator and pulsator-based WTP was also evaluated for raw water from the same source. To reduce down the turbidity below the acceptable level, the coagulant requirement for clariflocculator based WTP is comparatively less than pulsator based WTP. The floc blanket in the pulsator gets disturbed with a slight change in the coagulant chemistry and quantity.

Reverse Osmosis Treatment of Wastewater for Reuse as Process Water—A Case Study

The aim of this work was to purify mixed wastewater from three different production processes in such a manner that they could be reused as process water. The maximum allowed concentrations (MAC) from the Environmental Standards for emissions of substances released into surface water were set as target concentrations. Wastewaters contained solid particles, sodium, aluminium, chloride, and nitrogen in high amounts. Quantitatively, most wastewaters were generated in the production line of alumina washing. The second type of wastewater was generated from the production line of boehmite. The third type of wastewater was from regeneration of ion exchangers, which are applied for feed boiler water treatment. The initial treatment step of wastewater mixture was neutralisation, using 35% HCl. The precoat filtration followed, and the level of suspended solids was reduced from 320 mg/L to only 9 mg/L. The concentrations of ions, such as aluminium, sodium and chlorides remained above the MAC. Therefore, laboratory reverse osmosis was applied to remove the listed pollutants from the water. We succeeded in removal of all the pollutants. The concentration of aluminium decreased below 3 mg/L, the sodium to 145 mg/L and chlorides to 193 mg/L. The concentration of nitrate nitrogen decreased below 20 mg/L.

Difference in Bonding Strength of RMGIC according to Type of Hemostatic Agent in Primary Tooth

The purpose of this study was to compare the effect of the hemostatic agent containing aluminum chloride with hemostatic agent containing ferric sulfate on the shear bond strength of resin-modified glass ionomer cement(RMGIC) to dentin in primary tooth. Twenty extracted non-carious human primary teeth were collected in this study. The specimens were cut to expose dentin and polished. The specimens were randomly seperated into 3 groups for treatment; group I: polyacrylic acid(PAA), RMGIC; group II: aluminum chloride, PAA, RMGIC; group III: ferric sulfate, PAA, RMGIC Ten specimens from each group were subjected to shear bond strength test. The mean shear bond strength of each group was as follows: 10.07 ± 1.83 MPa in Group I, 7.62 ± 0.78 MPA in group II, 5.23 ± 0.78 MPa in group III. There were significant differences among all groups(p < 0.001). In conclusion, both aluminum chloride hemostatic agent and ferric sulfate hemostatic agent decreased the shear bond strength of RMGIC to dentin. And ferric sulfate hemostatic agent decreased the shear bond strength of RMGIC more than the aluminium chloride hemostatic agent.