Studies of the rate of gold sorption by the AM-2B anionite from cyanide-alkaline solutions

The paper presents the results of studies on the sorption leaching of gold-containing ore of the Vasilkovskoye deposit. Kinetic dependences of the sorption of gold and associated metals from cyanide-alkali solutions under different physical and chemical factors were obtained. It was found that gold on the AM-2B resin sorbed at a higher rate than, for example, copper and zinc. The solutions were analyzed using modern devices of a new generation: FT-IR spectrometer "Avatar 370". Laboratory studies were performed to determine the gold sorption rate by the AM-2B anionite from cyanide-alkaline solutions. It was found in the process of sorption of gold from multicomponent cyanide-alkali solutions on AM-2B anionite of mixed basicity, with the macroporous structure containing benzyl dimethylamine and dibenzyl dimethyl ammonium functional groups, that an important factor of qualitative and quantitative separation of gold and impurity metals is the concentration of cyanide and hydroxyl ions in solution. The temperature effect on the sorption rate of gold from cyanide-alkali solutions was studied with the temperature dependences F of t, Bt, of t, ln (l - F) of t, and D of t that show that the sorption process of dicyanoaurate ions is controlled by mixed diffusion.

CHARACTERIZATION OF CHEMICALS FROM PROSOPIS JULIFLORA (PJ) – A POTENTIAL ENHANCER FOR LIGHTWEIGHT POLYMER APPLICATIONS

The latest research is about ProsopisJuliflora’s mining and characterization officers. The fibres were cut, chemically treated using sodium and hydrochloric acid (alkali) solutions. Chemically modified and non-modified fibres have been analysed for their thermal, chemical, crystalline, electrical, morphological and tensile characteristics. The findings showed that a cellulose content was increased by 59.8 % with a reduction of amorphous content and humidity by chemical treatment with alkali. However, due to its acid-plus attacks whose values were lower than untreated, the treatment for hydrochloric acid reduced cellulosis material. There were four hundred and seventeen nm of crystalline fibre of alkaline therapy, less than one 68.01 nm. Thus the ProsopisJuliflora can be suggested for lightweight polymer applications as a possible reinforcement.

Thermally Treated Waste Silt as Filler in Geopolymer Cement

This study aims to investigate the feasibility of including silt, a by-product of limestone aggregate production, as a filler in geopolymer cement. Two separate phases were planned: The first phase aimed to determine the optimum calcination conditions of the waste silt obtained from Società Azionaria Prodotti Asfaltico Bituminosi Affini (S.A.P.A.B.A. s.r.l.). A Design of Experiment (DOE) was produced, and raw silt was calcined accordingly. Geopolymer cement mixtures were made with sodium or potassium alkali solutions and were tested for compressive strength and leaching. Higher calcination temperatures showed better compressive strength, regardless of liquid type. By considering the compressive strength, leaching, and X-ray diffraction (XRD) analysis, the optimum calcination temperature and time was selected as 750 °C for 2 h. The second phase focused on determining the optimum amount of silt (%) that could be used in a geopolymer cement mixture. The results suggested that the addition of about 55% of silt (total solid weight) as filler can improve the compressive strength of geopolymers made with Na or K liquid activators. Based on the leaching test, the cumulative concentrations of the released trace elements from the geopolymer specimens into the leachant were lower than the thresholds for European standards.

Improvements in Recovery Efficiencies of Phenols from Phenol Fraction Using Two-Stage Alkali Treatment

Experiments were carried out for the recovery of phenols from phenol fraction procured from tar distillation plant of Visakhapatnam steel plant by two stage alkali treatment, to study the effect of two-stage alkali treatment on the yield of phenols from phenol fraction. The results of the present investigation showed that two-stage alkali wash gives better yields of phenols compared to single stage alkali wash of the same phenol fraction with the same strength of alkali solution (NaOH). Also it is shown that maximum yield of phenols could be obtained with 35% strength of alkali. In the first stage 70% of 35% strength solution was used while in the second stage treatment 30% of the same strength solution was used. Improvements in the recovery efficiencies of phenols were found to be 47% more than those reported earlier in the single-stage extraction studies for the same strength of alkali solutions.

Synthesis of Inorganic Compounds in the Matrix of Polysaccharide Chitosan

Data related to the fabrication of hybrid materials based on the polysaccharide chitosan were systematized and reviewed. The possibility of using chitosan as a “host” matrix for in situ synthesis of inorganic compounds for the preparation of various types of composite materials were investigated. Coprecipitation of metal oxides/hydroxides (Fe, Ni, Al, Zr, Cu and Mn) with chitosan was carried out through the alkalinization of solutions containing metal salts and chitosan, with the addition of ammonia or alkali solutions, homogeneous hydrolysis of urea, or electrophoretic deposition on the cathode. The synthesis of transition metal ferrocyanides and hydroxyapatite was achieved from precursor salts in a chitosan solution with simultaneous alkalinization. The mechanism of composite formation during the coprecipitation process of inorganic compounds with chitosan is discussed. Composite materials are of interest as sorbents, coatings, sensors, and precursors for the production of ceramic and electrode materials.

Sensitive pH Monitoring Using a Polyaniline-Functionalized Fiber Optic—Surface Plasmon Resonance Detector

In this work, we report results on the fabrication and characterization of a surface plasmon resonance (SPR) pH sensor using platinum (Pt) and polyaniline (PANI) layers successively coated over an unclad core of an optical fiber (FO). The plasmonic thin Pt layer was deposited using a magnetron sputtering technique, while the pH-sensitive PANI layer was synthesized using an electroless polymerization method. Moreover, the formation of PANI film was confirmed by X-ray photoelectron spectroscopy (XPS) technique and its surface morphology was investigated using scanning electron microscopy (SEM). It was found that the PANI/Pt-coated FO-SPR pH sensor exhibits a fast and linear response in either acid or alkali solutions (pH operational range: 1 to 14). The proposed FO-SPR sensor could be used for biomedical applications, environmental monitoring or any remote, real-time on-site measurements.

Enzymatic Saccharification of Canola Straw and Oat Hull Subjected to Microwave-Assisted Alkali Pretreatment

Pretreatment of lignocellulosic biomass is a critical step in removing substrate-specific barriers to the cellulolytic enzyme attack. The study compared the effectiveness of microwave-assisted alkali pretreatment and alkali treatment in the enzymatic saccharification of canola straw and oat hull. Microwave pretreatments were employed by immersing the biomass in dilute alkali solutions (NaOH and KOH) at concentrations of 0, 0.75, and 1.5% (w/v) for microwave-assisted heating times of 6, 12, and 18 min. Alkali treatments were carried out using the same procedure but by soaking and without microwave heating. The highest glucose yields after enzymatic saccharification of both canola straw and oat hull were obtained when these feedstocks were ground using 1.6 mm hammer mill screen size and subjected to microwave-assisted alkali pretreatment using 1.5% and 0.75% NaOH for 18 min, respectively. SEM analysis indicated a more significant modification in the structure of biomass samples subjected to microwave-assisted alkali pretreatment compared to untreated and alkali-treated biomass samples. Results indicated that microwave-assisted alkali pretreatment with short residence time is effective in improving the glucose yield of canola straw and oat hull during enzymatic saccharification.