Optimasi Sintesis Ligan Diheksilditiofosfat (DHDTP) Menggunakan Response Surface Method (RSM)

Dihexyldithiophosphate (DHDTP) ligand is one of the homologues of dialkyldithiophosphate which is potentially better as an extractant in solvent extraction. The longer the chain in the dialkyldithophosphate compound, ability to dissolve into the organic phase is increasing compared to the shorter chain. The purpose of this study is to synthesize DHDTP ligands and find out the optimum reaction conditions to produce DHDTP ligands with optimal purity using the BoxBehnken (BBD) response surface method (RSM). DHDTP ligands are synthesized from P2S5 by reflux after addition of n-hexanol under a nitrogen gas environment. Ammonium carbonate is added to the reflux to pH 7, then evaporated to remove the solvent. The synthesized DHDTP ligand was then purified by column chromatography with a mobile phase methanol : aquadest (2.5% gradient). DHDTP ligands were examined for purity using a reverse phase HPLC with a mobile phase methanol: aquadest 3: 2. The purity of the best DHDTP synthesis results obtained was 87.34%. The DHDTP ligand formed was characterized to confirm the structure of its ligand compound by using a UV spectrophotometer in which the synthesis product showed maximum absorption at a wavelength of 212 nm and mass spectroscopy ES- with m / z 297.1687.

Dissolution kinetics of rare earth metal phosphates in carbonate solutions of alkali metals

Treatment of apatite raw materials is associated with the formation of large-tonnage waste – phosphogypsum. The content of rare earth metals in such waste reaches 1 %, which makes it possible to consider it a technogenic source for obtaining rare earth metals and their compounds. Up to the present moment, there are neither processing plants, nor an efficient process flow to handle phosphogypsum dumps. It is rational to use a way that involves extraction of valuable components and overall reduction of phosphogypsum dumps. Such process flow is available with carbonate conversion of phosphogypsum to alkali metal or ammonium sulfate and calcium carbonate upon the condition of associated extraction of rare earth metal (REM) compounds. Associated extraction of REM compounds becomes possible since they form strong and stable complexes with hard bases according to Pearson, which among other things include carbonate, phosphate and sulfate anions. Formation of lanthanide complexes with inorganic oxygen-containing anions is facilitated by the formation of high-energy Ln-O bonds. The study focuses on the dissolution of lanthanide phosphates in carbonate media. It was established that formation of REM carbonate complexes from their phosphates is a spontaneous endothermic process and that formation of lanthanide carbonates and hydroxides serves as thermodynamic limitation of dissolution. A shift in equilibrium towards the formation of carbonate complexes is achieved by increasing the temperature to 90-100 °C and providing an excess of carbonate. The limiting stage of REM phosphate dissolution in carbonate media is external diffusion. This is indicated by increasing rate of the process with an intensification of stirring, first order of the reaction and the value of activation energy for phosphate dissolution from 27 to 60 kJ/mol. A combination of physical and chemical parameters of the process allowed to develop an engineering solution for associated REM extraction during carbonate conversion of phosphogypsum, which included a 4-5 h conversion of phosphogypsum at temperature of 90-110 °C by an alkali metal or ammonium carbonate solution with a concentration of 2-3 mol/l. As a result, a solution with alkali metal (ammonium) sulfate is obtained, which contains REMs in the form of carbonate complexes and calcium carbonate. The rate of REM extraction into the solution reaches no less than 93 %. Rare earth metals are separated from the mother liquor by precipitation or sorption on anion exchange resins, while the excess of alkali metal or ammonium carbonate is returned to the start of the process.

The Enhancement of Enargite Dissolution by Sodium Hypochlorite in Ammoniacal Solutions

The dissolution of both copper and arsenic from a copper concentrate was investigated in oxidative ammonia/ammonium solutions at moderate temperatures and atmospheric pressure. The main parameters studied were temperature, pH, concentrations of different ammonia salts, the presence of sodium hypochlorite, pretreatment with sodium chloride, and curing period. In all ammoniacal solutions studied, increasing the temperature enhanced the dissolution of copper, but the dissolution of arsenic remained marginal. Mixing the copper concentrate with sodium chloride and leaving it to rest for 72 h before leaching in ammoniacal solutions significantly increased the dissolution of copper and slightly increased the dissolution of arsenic from the concentrate. A maximum of 35% of Cu and 3.3% of As were extracted when ammonium carbonate was used as the lixiviant. The results show relatively rapid dissolution of the concentrate with the addition of sodium hypochlorite in ammonium carbonate solution, achieving a dissolution of up to 50% and 25% of copper and arsenic, respectively. A copper dissolution with a non-linear regression model was proposed, considering the effect of NaClO and NH4Cl at 25 °C. These findings highlight the importance of using the correct anionic ligands for the ammonium ions and temperature to obtain a high dissolution of copper or arsenic. The results also showed that the curing time of the packed bed before the commencement of leaching appeared to be an important parameter to enhance the dissolution of copper and leave the arsenic in the residues.

SYNTHESIS, CHARACTERIZATION AND ANTIMICROBIAL ANALYSIS OF PHENAZINEAZO-1-NAPHTHOL PRODUCED FROM PHENAZINE-1- CARBOXYLIC ACID ISOLATED FROM PSEUDOMONAS AERUGINOSA

The search for effective antibiotics continues among scientists as more resistant pathogenic microorganisms evolve, and some already existing antibiotics used in treatment of infections are gradually becoming less effective against the pathogens causing the infections thus, making life unbearable to their hosts. Phenazines are para diazine with annular two nitrogen atoms at 1,4 positions joined to two phenyl group in a side by side pattern. The derivatives of the compound are primarily produced from microorganisms and can also be synthesized, example of this is phenazine-1-carboxylic acid (PCA). In the present study, phenazine-1-carboxylic acid was biosynthesized from Pseudomonas aeruginosa isolated from soil. Subsequently, phenazineazo-1- naphthol was synthesized from the produced phenazine-1-carboxylic acid following amidation with Ammonium carbonate and Hoffmann degradation reactions to reduce the compound to phenazineamine under reflux condition of 50 °C before diazotization and coupling with 1-naphthol. The results obtained from the UV-vis, IR and NMR spectra were able to elucidate the important peaks in the compound at reasonable extents. The concentrations of 50 ?g/mL, 100 ?g/mL, 150 ?g/mL, 200 ?g/mL, 30 ?g/mL Augmentin (Au, control drug), 30 ?g/mL Oflocitoxin (OFX, control drug) and raw sample of the compound were able to inhibit Staphylococcus aureus and Escherichia coli at some millimeter ranges while Aspergillus fumigatus was inhibited by all the sample concentrations but resisted 30 ?g/mL Augmentin (Au) and Oflocitoxin (OFX) control drugs from the antimicrobial analysis carried out. In general, the compound was active against the organisms when compared to the concentrations of control antibiotic drugs used. The minimum inhibitory concentration of the compound was estimated at 50 ?g/mL concentrations.

MONITORING OF RHAGOLETIS CERASI L. THROUGH THE DECIS TRAP AT IAȘI-ROMANIA

Rhagoletis cerasi (L.) is the main agent of damage to sweet cherry plantations. Found in all sweet cherry plantations, it is important for an integrated phytosanitary protection of the crop. The population dynamics in the Iasi area was monitored at different time intervals. The climatic conditions of the year and the biological reserve favored the appearance and development of the pest studied. The first catches were recorded on 12 May and the highest number of catches was recorded on 17 June 2020. Adult monitoring Rhagoletis cerasi (L.) was performed using “Decis Trap”, an attractive trap containing ammonium carbonate, which attracts by its orange color and fights with the active substance deltamethrin providing a duration of protection of 5 months. The appearance and dynamics of pests have directly influenced the phytosanitary protection program. The observations were made during the vegetation period of the cherry plantation within the Research and Development Station for fruit growing in Iași in 2020.