RESEARCH INTO DYNAMICS OF ADSORPTION OF HEAVY METALS ON ACID-ACTIVATED BENTONITE

Acid activation of bentonite clay is a common way to obtain porous adsorbents of organic and inorganic substances. Acid activation with preservation of the layered structure is the initial stage of chemical modification. Acid treatment of natural aluminosilicates is aimed at increasing their adsorption capacity and specific surface area. In industrial practice, water treatment of heavy metals is in most cases carried out bypassing the liquid through a fixed layer of backfill. Therefore, in this study, we studied the dynamics of adsorption with the definition of the main characteristics of the process: the speed of the working zone, the coefficient of protective action, the length of the working layer, the loss of protective action time, the duration of the sorption column before leakage. In addition, the establishment of the basic laws of this process can be used to determine the optimal parameters of the sorption material at a given initial characteristic — the length of the layer of the sorption column, the filtration rate. We have studied the possibilities of chemical modification of granular bentonite during acid-salt treatment. Through sorption columns with a height of 0.1; 0.2 and 0.3 m, filled with samples of modified bentonite, were passed model solutions of salts Fe2+, Mn2+, Cu2+ and Cd2+ with a concentration of cations of 0.01 g/dm3. The flow rate of the solution was 0.5; 1.0 and 1.5 m/h. Experimental data show that the optimal sorption values ​​are obtained for samples of modified bentonite: at the same height of the sorbent layer and flow rate, the duration of the layer before skipping in modified samples is 1.25—1.52 times higher than in unmodified ones. It is established that the sorption time before skipping mainly depends on the flow rate and the height of the sorbent layer. Thus, at a layer height of 0.3 m and the same rate of transmission of the solution, the sorption time is up to 3.5 times greater than at a layer height of 0.1 m for all investigated cations.

Glauconite as a sorbent of 4-nitrophenol

The sorption properties of glauconite from Beloozersk deposits (Saratov region) for 4-nitrophenol (4-NF) have been investigated. The effect of glauconite on pH and 4-nitrophenol structure in solution is estimated. It is shown that glauconite increases pH of aqueous environment to 8 and shifts the equilibrium towards the formation of aci-form 4-NF. The conditions of sorption 4-NF by glauconite are established: the sorption time 20 min, the mass of the sorbent (0.50–1.0) g. The isotherm of sorption by 4-NF glauconite has been obtained; its interpretation is given using the Langmuir and Freundlich equations. The main quantitative sorption characteristics of glauconite such as recovery (R = 64%), distribution coefficient (D = 88) and the Langmuir and Freundlich constants for 4-nitrophenol are calculated. These experiments indicate the potential use of the glauconite from Beloozersk deposits (Saratov region) for 4-NP from various waters.

The Use of Red Mud and Black Nickel Mud in Sorption of 3,5-Dichlorophenol

This article discusses the use of alternative inexpensive adsorbents – wastes from the metal production - red mud (RM) and black nickel mud (BNM) and their sorption efficiency in 3,5-dichlorophenol removal. Chlorophenols are organic compounds consisting of a benzene ring, OH groups and chlorine atoms. The effects of adsorbent dose, contact time, and temperature on sorption process were monitored. The results showed that the optimal conditions to achieve the highest sorption efficiency of 3,5-dichlorophenol were reached with the use of black nickel mud at the amount (2.0 g), sorption time (1 hour) and at increased temperature (45 °C). The sorption efficiency under these conditions was 87.99 %. With increasing sorption time, the sorption efficiency decreased and desorption occurred. The same behaviour was observed using red mud of the same amount (2.0 g) at the same temperature (45 °C); however, after 1 hour, sorption efficiency was slightly reduced (85.16 %) compared to black nickel mud. Anyway, both of used materials are suitable for the use as alternative sorbents of 3,5-dichlorophenol under suitable conditions.

Sorption of petroleum products with natural sorbents

This article presents the results of a study of cleaning the water surface from contamination with petroleum products. Kulantaussky vermiculite, the birthplace of the Turkestan region, was studied as a sorbent. Studies have shown that the modified vermiculite is able to retain the sorbed oil up to 2 days after the expiration of the main sorption time (4 hours). It is established that the oil capacity depends on the thickness of the oil film, the sorption time and the amount of the sorbent taken.

Removal of Methylene Blue and Congo Red Using Adsorptive Membrane Impregnated with Dried Ulva fasciata and Sargassum dentifolium

Biosorption is a bioremediation approach for the removal of harmful dyes from industrial effluents using biological materials. This study investigated Methylene blue (M. blue) and Congo red (C. red) biosorption from model aqueous solutions by two marine macro-algae, Ulva fasciata and Sargassum dentifolium, incorporated within acrylic fiber waste to form composite membranes, Acrylic fiber-U. fasciata (AF-U) and Acrylic fiber-S. dentifolium (AF-S), respectively. The adsorption process was designed to more easily achieve the 3R process, i.e., removal, recovery, and reuse. The process of optimization was implemented through one factor at a time (OFAT) experiments, followed by a factorial design experiment to achieve the highest dye removal efficiency. Furthermore, isotherm and kinetics studies were undertaken to determine the reaction nature. FT-IR and SEM analyses were performed to investigate the properties of the membrane. The AF-U membrane showed a significant dye removal efficiency, of 88.9% for 100 ppm M. blue conc. and 79.6% for 50 ppm C. red conc. after 240 min sorption time. AF-S recorded a sorption capacity of 82.1% for 100 ppm M. blue conc. after 30 min sorption time and 85% for 100 ppm C. red conc. after 240 min contact time. The membranes were successfully applied in the 3Rs process, in which it was found that the membranes could be used for five cycles of the removal process with stable efficiency.

Droplet Spreading on Unidirectional Fiber Beds

This study reports a method to analyze parametric effects on the spread flow kinetics of fluid droplets on unidirectional fiber beds. The investigation was undertaken in order to guide the design of droplet arrays for production of an out-of-autoclave (OoA) prepreg featuring discontinuous resin distribution, referred to here as semi-preg. Volume-controlled droplets of a resin facsimile fluid were deposited on carbon fiber beds and the flow behavior was recorded. The time to full sorption (after deposition) and the maximum droplet spread distance were measured. Experiments revealed that fluid viscosity dominated time to full sorption—doubling the viscosity resulted in an 8- to 20-fold increase in sorption time, whereas doubling fabric areal weight increased the time only by a factor of three. Droplet spread distance was nearly invariant with fiber bed architecture and fluid viscosity. A series of droplet arrays were designed, demonstrating how the results can be leveraged to achieve different resin distributions to produce semi-preg optimized for OoA cure.

DETERMINATION OF VANADIUM (V) TRACE AMOUNTS IN OIL SLUDGE AFTER PRELIMINARY CONCENTRATION WITH POLYMER SORBENT

A modified sorbent based on copolymer of maleic anhydride with methacrylic acid was proposed for sorption of vanadium (V) concentration. A polymer chelating sorbent with fragments of para-amino salicylic acid was used in the work. Optimal sorption conditions were determined and the dependence of sorption capacity on the acidity of the solution studied. At pH 5, the degree of sorption attains its maximum. The effect of ionic strength on vanadium sorption was studied. Studies have shown that the ionic strength up to 0.6 mol/l does not affect the sorption, after 0.6 mol/l the increase in the ionic strength at the beginning gradually, and then sharply decreases the sorption. The effect of ionic strength on vanadium sorption was studied to show that the ionic strength up to 0.6 mol/l does not affect the sorption, and after 0.6 mol/l the increase in the ionic strength at the beginning gradually, and then sharply decreases the sorption. All further experiments were carried out in the solutions with an ionic strength of 0.6. It was found that as the concentration of vanadium rises in the solution, the amount of sorbed metal increases, and at a concentration of 8.10-3 mol/l it becomes maximum (pH = 5, CV5+ = 8.10-3 mol/l, vtotal = 20 ml, msorb. = 0.03 g, SC = 243 mg/g). The isotherm of vanadium (V) sorption with the synthesized sorbent was constructed. Sorption equilibrium is achieved within 1 hour of contact between the solution and the sorbent. Further growth in the sorption time does not change sorbent’s characteristics. The sorbent extracts vanadium (V) from solutions with a recovery rate of 93%. The effect of different mineral acids (HClO4, H2SO4, HNO3, HCl) of identical concentrations on vanadium (V) desorption from the sorbent was also studied. The results of the analysis showed that the maximum desorption of vanadium (V) occurs in perchlorate acid. The developed method was applied to determine the trace amounts of vanadium in oil sludge with preliminary concentration.

Sorption of Uranium (VI) Ions by a Sorbent Based on a Copolymer of Maleic Anhydride with Styrene Modified by N, Nand#39;-diphenylguanidine

In this paper the results of a study on the extraction and concentration of micro-quantities of uranium (VI) with a polymeric chelating sorbent with fragments of N, N and#39;diphenylguanidine is discussed. There was studied a static sorption capacity on K+ ions ((SSC = 9.3 mmol / g) and there were determined the ionization constants of ionogenic groups ( =3.97; =8.47) by potentiometric titration. The optimal conditions of the sorption of elements (pHopt, sorption time - τ, the influence of ionic strength - μ) were determined by the dependence of the sorption capacity (SC, mg/g) on the parameter being studied; the sorption capacity of the sorbent (SC) was determined from the saturation curve constructed under optimal sorption conditions. The maximum degree of extraction of uranium by sorbents is achieved from solutions with pH 5. Sorption equilibrium is achieved within 2 hours of contact of the solution with the sorbent. With an increase in the concentration of the uranyl ion in the solution, the amount of the sorbed metal increases, and at a concentration of 8•10–3 mol/l, it becomes maximal (pH = 5, = 8•10–3 mol/l, Vgen = 20 ml, msorb. = 0.05 g, SC = 1258 mg/g). Limits of detection (3, n=20) are 13.9 ng/ml. The effect of various mineral acids(HClО4, H2SО4, HNО3, HCl) with the same concentrations on the desorption of uranium (VI) from the sorbent was studied. The developed technique was applied to determine uranium in oil sludge.

Kinetics of Oil Sorption by Material Based on Leaf Litter

Studies of leaf litter as a sorption material with respect to oil at various temperatures have been carried out. It has been revealed that with process temperature increasing, the samples sorption capacity decreases. The oil sorption mechanism has been studied. It has been shown that the active sorption time was in the interval from 60 to 600 seconds. It has been proved that at the time of oil and sorption material contact for more than 600 seconds, the desorption process began. Kinetic dependencies of oil absorption by the proposed sorption material have been constructed and analyzed. The reaction order determination by a graphic method has showed that obtained functions with a high degree of correlation can be attributed to first-order heterogeneous reactions. Have been calculated thermodynamic parameters confirming the absence of a chemical reaction between oil and leaf litter. The carried out researches determine the most acceptable parameters of oil sorption by material based on leaf litter.

Biomass Modification Using Cationic Surfactant Cetyltrimethylammonium Bromide (CTAB) to Remove Palm-Based Cooking Oil

Adsorption based on natural fibre seems to widely used for oily wastewater recovery due to its low cost, simplicity, feasibility, easy handling, and effectiveness. However, oil sorbent based on natural fibre without modification has low adsorption capacity and selectivity. Thus, this paper proposes chemical modification of sago hampas to improve its adsorbent efficiency for the removal of palm-based cooking oil. The chemical modification was performed using a cationic surfactant, cetyltrimethylammonium bromide (CTAB). The chemical and surface properties of both unmodified and modified sago hampas were characterized by Fourier-Transform Infrared (FTIR) and Scanning Electron Microscopy (SEM). Parameters studied for the removal of cooking oil using modified sago hampas were sorption time, adsorbent dosage, and initial pH. The removal capacity was also compared using unmodified sago hampas. The results showed that additional functional groups were introduced on the surface of modified sago hampas. Modified sago hampas also showed a greater porosity than unmodified sago hampas. These properties enhanced the adsorption of palm-based cooking oil onto the surface of modified sago hampas. Modified sago hampas shows better removal of palm-based cooking oil than unmodified sago hampas, where 84.82% and 68.08% removal were achieved by modified and unmodified sago hampas, respectively. The optimum adsorption of palm-based cooking oil was identified at 45 min sorption time, pH 2, and 0.2 g adsorbent dosage.