Addition Of Alkali Research Articles

Air side-stream ammonia stripping in a thin film evaporator coupled to high-solid anaerobic digestion of sewage sludge: Process performance and interactions

Air side-stream ammonia stripping in a thin-film evaporator (TFE) is proposed for the first time to control total ammonia nitrogen (TAN) concentration in a centralized full-scale plant performing high-solid anaerobic digestion (HSAD) of sewage sludge (SS). In this process, anaerobically digesting sludge (ADS) is continuously recirculated from the digester to the TFE unit where ammonia is stripped by an air stream. The stripped ammonia reacts with sulfuric acid in an absorption unit to produce ammonium sulfate. Overall, HSAD coupled to air side-stream ammonia stripping results in a twofold production of fertilizers (i.e. ammonium sulfate and SS digestate) recycling nutrients from organic wastes in agreement with the principles of circular economy. This study evaluates the influence of different operational airflow rates, temperatures and CO2 concentrations on air side-stream ammonia stripping in the TFE without alkali addition and the impact of air-based ammonia stripping on HSAD performance at full-scale. The study also investigates the chemistry and the interaction between the ammonia and carbonate subsystems of ADS and clarifies the stoichiometric relationship between ammonia and CO2 stripping.

Influence of alkali treatment on physio-mechanical properties of jute–epoxy composite

ABSTRACT The present study deals with development of jute epoxy composite using compression moulding technique and assessing the influence of sodium hydroxide (NaOH) on the mechanical properties of the developed composite. Three different concentrations of NaOH alkali (5%, 10% and 15%) is considered in the present study. Various tests carried out indicates that the addition of alkali enhances the tensile strength, flexural strength and impact strength up to 5% concentration of NaOH. Further addition of NaOH results in reduced mechanical properties. It is found that the impact strength of the alkali treated composites are better than non treated composites. The optimal concentration of 5% NaOH is suggested for treatment of the fibres used in composites.

Properties of lightweight alkali activated controlled Low-Strength material using calcium carbide residue – Fly ash mixture and containing EPS beads

This research aims to use of alkali activated binder containing expanded polystyrene (EPS) beads for producing lightweight controlled low strength materials (CLSM). Sodium hydroxide (NH) solution and sodium silicate (NS) were used as alkali activators. NH concentration was set as a constant of 6 Molar. The mixture of fly ash (FA) and calcium carbide residue (CR) at a ratio of 75:25 by weight was used as a binder. EPS beads was used as a lightweight aggregate and the binder to EPS beads ratio was varied from 1:2.50 to 1:3.00 by volume. Workability in terms of flow was controlled between 200 and 300 mm. The compressive strength at 6 h up to 28 d and water absorption of lightweight alkali activated CLSM were determined. In addition, XRD and SEM of lightweight alkali activated CLSM were also investigated. The results revealed that the compressive strengths of lightweight alkali activated CLSM rapidly increased in the first 12 h, which were from 451 kPa to 731 kPa. The ratio of binder to EPS beads at 1:2.50 by volume was the optimum ratio and the ratio of NH:NS at 1:0.4 gave the highest compressive strength of lightweight alkali activated CLSM. Lightweight alkali activated CLSM obtained from this study had the compressive strength of 1,500–3,000 kPa and the density of 750–900 kg/m3 at 28 d, which can be used as structural backlinking.

Forced hydrolysis of FeCl3 solutions in the presence of Cr3+ ions

Forced hydrolyses of FeCl3 solutions in the presence of Cr3+ ions without alkali addition were investigated at 160 and 200 °C. These precipitation systems were compared to corresponding reference systems. The isolated precipitates were characterized with XRD, 57Fe Mössbauer, FT-IR, FE SEM and photocatalytic measurements. Although chromium was not detected by EDS (Energy Dispersive X-ray Spectroscopy), the analysis of samples precipitated in the presence of Cr3+ ions showed several effects which can be attributed to the presence of these ions in the starting solutions. These effects are specifically well pronounced for samples obtained at 200 °C. For the highest concentration of Cr3+ ions and upon heating at 200 °C the transformation kinetics β-FeOOH to α-Fe2O3 was impeded. Relative intensities of prominent diffraction lines 104 and 110 of α-Fe2O3 changed as a result of the presence of Cr3+ ions. Changes in the size and formation of lemon-like particles instead of cube-like α-Fe2O3 particles were also noticed. The presence of Cr3+ ions in hydrolysing FeCl3 solution influenced the photocatalytic degradation of rhodamine B. Since no specific adsorption of Cr3+ ions occurred in the acidic pH medium, it was inferred that traces of Cr3+ ions enter into the structural tunnels of β-FeOOH crystals. The associates Cl−-Cr3+ are formed, which in the next step destabilize the crystal structure of β-FeOOH particles. Cr3+ ions leave the crystal structure upon dissolution of β-FeOOH. It can be assumed that α-Fe2O3 crystals start to grow on very fine and thin β-FeOOH crystallites which were not completely dissolved, but were previously affected by Cr3+ ions.

Increasing the strength of pellets made of titanium-magnetite concentrates when using additives containing barium and strontium

In the process of pelletizing of titanium-magnetite ores concentrate, the high viscosity of the forming titaniferous melts makes the pellets sintering difficult resulting in their low strength. The reserves of the existing methods of solving the problem by addition of oxides of waste rock and therefore decreasing titanium concentration or by assortment of optimal heat mode of the technological process are exhausted. An ability to decrease the viscosity of titaniferous melt by application monoxides of iron, manganese, boron and alkali oxides of potassium, sodium and strontium for its dilution was considered. It was shown that the alkali additives were a powerful method to decrease the viscosity of silicate melts. The purpose of the study was to estimate an ability to in-crease the strength of iron ore pellets of titanium-magnetite concentrates by addition barium-strontium carbonate ores of Murunskoye deposit into the charge, which have and increased content of oxides of barium and strontium (up to 19% BaO and up to 5% of SrO). As a result of the experiment a mechanism of pellets strengthening at addition carbonate barium-strontium ores was established. The increase of the burnt pellets strength was reached up to 35–40%. It was shown, that the pellets strengthening was stipulated by modi- fication of slag melt structure with destruction of polymer chains and by decrease of melt viscosity. The increase of pellets strength will contribute to decreasing of fines yield during their transportation and to improving of gas-dynamic mode of shaft facilities – blast furnaces and metallization furnaces. The forecast effect due to application of additives in the pellets is estimated as follows: decrease of coke rate by 4.5–5.8 kg/t of hot metal and decrease of cast iron cost by 49.5–64.3 Rbl/t of cast iron.

Printing with Natural Dye Extracted from Impatiens glandulifera Royle

Invasive alien plants that damagingly overgrow native ecosystems can be beneficially used to produce natural dyes. Natural dyes are healthier and more environmentally friendly than synthetic dyes, so their use on textiles and other products that come into contact with humans is desirable. In this study, the possibility of using a natural dye extracted from the purple petals of the invasive plant Impatiens glandulifera Royle (Himalayan balsam) for screen printing on various substrates; woven fabrics and different papers made from virgin fibers, recycled fibers, and from fibers of Japanese knotweed, was investigated. The prints were evaluated by color measurements and fastness properties. With the violet dye extract, purple-brown prints were obtained on papers made from Japanese knotweed, and more brown prints on other substrates. They had excellent rub fastness but faded significantly when exposed to light. The wash fastness of the prints on cotton fabrics was moderate and poor on polyester fabrics, but the prints had good resistance to wet ironing. The addition of acid to the printing paste resulted in a lighter violet color, the addition of alkali caused a drastic color change to green, both additives increased the light fastness of the prints but reduced the fastness on fabrics to wet treatments.

Enhanced biomethanization of waste polylactic acid plastic by mild hydrothermal pretreatment: Taguchi orthogonal optimization and kinetics modeling

Polylactic acid (PLA) plastic is becoming a popular alternative to traditional petroleum-based plastics, but the biodegradability in engineered biological system is still a matter of concern. In this study, the biodegradability of PLA plastic at mesophilic and thermophilic AD were investigated, and a hydrothermal pretreatment was proposed to enhance the hydrolysis of PLA plastic and subsequent biomethanization. For raw PLA plastic, the biodegradation results indicated that PLA was hardly biodegraded at mesophilic conditions (only 50.5 ± 0.5 mL/g VS after 146 days). Although it was converted into biogas at thermophilic conditions after long incubation period (442.6 ± 1.1 mL/g VS), the long digestion time (T90 95.8 days) was destined to be infeasible for practical application. In contrast, hydrothermal pretreatment significantly enhanced the hydrolysis rates of PLA plastic in AD process from 0.001 day-1 for raw PLA plastic to 0.004–0.111 day−1. By balancing biogas production efficiency, energy and reagent cost, the conditions of 200 °C, 10 min and no alkali addition were recommended for hydrothermal pretreatment of waste PLA plastic in practice. At the optimized hydrothermal pretreatment conditions, 460.1 ± 25.0 mL/g VS was achieved in less than 30 days, which was comparable for AD of food waste (FW). Furthermore, LC-QEMS analysis proved that cleavages of ester bonds in PLA and its reaction with water molecule was the mechanism of triggering the hydrothermally decomposition of PLA. These results suggested the PLA-plastic waste co-mingled with OFMSW could be efficiently biomethanized into biogas by involving a mild hydrothermal pretreatment in practical application.

Performance and stability of biogas recirculation-driven anaerobic digestion system coupling with alkali addition strategy for sewage sludge treatment

Wastewater treatment plants are particularly challenging with the treatment and disposal of sewage sludge produced from the treatment units due to its high costs and environmental hazards. In this study, a biogas recirculation-driven anaerobic digestion (AD) system was developed with upward shear force being provided by biogas recirculation coupled with the alkali addition strategy, targeting biogas upgrading, sludge stabilization, and sludge flocculation simultaneously, thus reducing the sludge management costs. Compared to the conventional AD system, the novel biogas recirculation-driven AD system could achieve biogas upgrading with 10% higher CH4 content. Besides, the combination of NaOH and Ca(OH)2 addition strategy obviously improved sludge settleability and dewaterability compared to the single NaOH addition strategy. Owing to the attraction between negatively charged sludge particles and Ca2+ ions, the available Ca2+ in the former AD system may facilitate the re-flocculation and P immobilization in solid digestate, fix partial CO2 with less CO2 emission, and bridge with some sludge flocs. Moreover, 12.6% lower net cost for sludge management was achieved by this biogas recirculation-driven AD system together with the combination alkali addition strategy, which is regarded as a promising integrated multi-purpose system for sludge treatment.

Effect of Silane Coupling Agent on Flexural Strength and Hardness of Wheat Straw Polystyrene Composites

In the present research work, the effect of silane treatment along with alkali treatment on flexural strength, flexural modulus, and hardness investigated. Wheat straw as a filler was added (5%, 10%, 15% and 20%) to polystyrene matrix to prepare wheat straw polystyrene composite. The wheat straw fibre was first treated with 20% NaOH and 1% silane coupling agent to prepare wheat straw polystyrene composite. The compounding process was carried out in twin-screw extruder and samples were prepared by the compression moulding process. There was an increase in flexural modulus (214%), flexural strength (44%), and hardness (28%) of composite with the addition of alkali and silane treated wheat straw fibre.

Relationship between Phase Composition and Mechanical Properties of Peat Soils Stabilized Using Oil Shale Ash and Pozzolanic Additive

Construction of road embankments in peatlands commonly involves replacement of the peat with a fill-up soil of an adequate load-bearing capacity. This usually requires a lowering of the water level, turning a peatland from a carbon sink to a source of greenhouse gases. Thus, alternatives are sought that are less costly in both economic and ecological terms. Mass-stabilization technology can provide a cheap substitute for Portland cement. Calcareous ashes (waste materials), supplemented with pozzolanic and alkali additives to facilitate and accelerate the setting and hardening processes, are attractive alternatives to soil excavation or replacement techniques. Silica fume and waterglass were used as pozzolanic agents and KOH as a soil-alkalizing agent. X-ray fluorescence (XRF), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) analyses and stress–strain tests were performed for the hardened samples. Crystallization of alkali feldspars was observed in all test samples. Comparable hardening of peat soil was achieved for both ashes. It was shown that the ashes of Estonian kukersite (oil shale) from both pulverized firing and a circulating fluidized bed incineration process (produced in energy sector as quantitatively major solid waste in Estonia) can be used as binding agents for peat stabilization, even without the addition of Portland cement. Hardened peat soil samples behaved as a ductile material, and the cellulose fibers naturally present in peat gave the peat–ash composite plasticity, acting mechanically in the same way as the steel or glass fiber in ordinary reinforced concrete. The effect of peat fiber reinforcement was higher in cases of higher load and displacement of the composite, making the material usable in ecological constructions.

The effect of alkali type on IFT value for surfactant-alkali injection

The aim of this research is to acknowledge alkali effect on surfactant-alkali on IFT value and to acknowledge temperature on surfactant-alkali IFT stability. There are six surfactant-alkali solutions utilized in this research. Meanwhile solution compatibility test in this research consist of Aquos Stability, CMC, IFT, phase behaviour test by utilizing micro emulsion observation for 24 hours and thermal stability on reservoir temperature (60o C) for 7 days. There are two surfactant-alkali solution type that pass selection stage, which are 5% salinity OGEP 400 OLEAT with 0.3% concentrate and NaOH with 0.1% concentration with surface tension of 5.176x10-3 dyne/cm, phase behaviour reading in phase 1, unstable thermal stability test with IFT measurement after thermal as much as 1.385×10-2 to 2.416×10-2 dyne/cm, filtration ratio of the filtration test is as much as 1.2 ml/second and recovery factor of imbibition result is as much as 75.5%. Meanwhile for alkali Na2CO3 in 0.5% concentration with surface tension test result of 3.379×10-3 dyne/cm, phase behaviour reading in phase 1, a relatively stable thermal stability test with IFT measurement after thermal of 2.42×10-2 to 2.871×10-2 dyne/cm, filtration ratio of filtration test as much as 1.17 ml/second and recovery factor from imbibition result as much as 57.8%. The obtained result shows that alkali addition is proven to be able to lower surfactant IFT to 10-3 dyne/cm. This finding can be utilized as a basic of EOR application in sand stone formation.

Tailoring growth modes by excess alkali addition in magnetron sputtered potassium sodium niobate thin films

This work reports on the deposition of thin film potassium sodium niobate sputtered from equimolar and excess alkali targets, showing that the growth mode can be shifted towards recrystallized grain growth without substrate heating, while structural and electrical material properties are improved. In particular, we investigate the influence of abnormal grain growth and its attenuation in KNN thin films. This is accompanied by a comprehensive crystallographic analysis of the obtained crystal structures involving wide-range reciprocal space mapping, temperature-dependent X-ray diffraction and elemental analysis associated with the different growth modes. Moreover, we report on the phase segregation within the processed thin film discovered by scanning transmission electron microscopy, which does not show in conventional elemental analysis of the film surface. Verification of the ferroelectric properties of the films is given by piezoresponse force microscopy, which also enables a study of the ferroelectric domains.

A New Benzylated Fatty Acid Amide Amphoteric Surfactant Derived from Hydrogenated Castor Oil with Ultra‐Low Interfacial Tension between Crude Oil and Brine

AbstractHydrogenated castor oil from castor oil is promisingly used as raw materials for lubricants, coatings, cosmetics, and pharmaceutics due to high melting point and stable physical properties. However, the chemical modification of the hydrogenated castor oil has been rarely investigated. Here, we report a N‐phenyl‐fatty‐amido‐1‐propyl‐N,N‐dimethyl‐amino‐carboxyl‐betaine surfactant derived from hydrogenated castor oil with excellent interfacial properties through a rapid synthetic process, including direct alkylation, amidation, and quaternization. The interfacial tension between crude oil and brine was ultra‐low for a low dosage of 0.007 g L−1 of surfactant in aqueous solution without any alkali addition, which implies a potential application in enhanced oil recovery.

Influence of Surfactant and Weak-Alkali Concentrations on the Stability of O/W Emulsion in an Alkali-Surfactant-Polymer Compound System.

Emulsions have emerged as advanced materials for wide industrial applications because of their unique properties. In the actual application in oilfields, emulsions can significantly enhance oil recovery. In the present study, the stability test shows that the concentrations of a surfactant and alkali and salinity have a great influence on the stability of the emulsion, but the addition of excessive chemical agents may adversely affect the emulsion stability. The addition of excessive alkali causes the phase inversion behavior of the emulsion to be discovered, which is also the main reason for the destabilization of the oil-in-water emulsion. Rheological experiments reveal that the emulsion produced by the chemical-flooding fluid is a pseudoplastic fluid, and the apparent viscosity decreases with the increase of the shear rate. Core-flooding experiments were conducted to study the effect of the emulsion stability on enhanced oil recovery, and the results indicate that the system with a better emulsion stability has higher oil recovery and displacement pressure.

Enhanced charge carrier lifetime and mobility as a result of Rb and Cs incorporation in hybrid perovskite

Alkali addition in organic–inorganic perovskite has become the standard recipe for achieving solar cells with efficiencies exceeding 20%, but the mechanism is not well understood. We use non-contact carrier lifetime measurements, mobility measurements, and synchrotron-based x-ray characterization techniques to show that there is a unique benefit to adding hybrid perovskite samples with Rb and Cs simultaneously. When either Rb or Cs is added, charge carrier mobility increases with alkali concentration. Charge carrier lifetime benefits from alkali incorporation as well, but is optimized with only moderate concentration at 1%. When both Rb and Cs are introduced, however, the high mobility is maintained and the charge carrier lifetime increases considerably. Our results show that when incorporated alone, Rb and Cs have very similar roles in a perovskite crystal, but when co-added, halide distribution becomes homogenized correlating with improved charge transport properties.

A practical and economically feasible surfactant EOR strategy: Impact of injection water ions on surfactant utilization

One grand challenge of surfactant technologies in high salinity sandstone reservoirs is the surfactant retention and its utilization for commercial projects. A proven mitigation strategy to reduce surfactant retention is to soften the seawater or produced brine and add alkali with the surfactant and polymer. However, softening produced brine can be costly and the addition of alkali can impose other issues such as scale and produced fluid separation. A comprehensive chemical enhanced oil recovery (CEOR) laboratory program was carried out to compare different surfactant formulations for both alkali-surfactant-polymer (ASP) and surfactant-polymer (SP) implementation in a giant Middle East sandstone oil reservoir with high salinity on the order of 160,000 ppm. The efficacies of ASP and SP floods were investigated in laboratory corefloods and simulations with emphasis on surfactant retention to improve techno-economic feasibility.Both ASP and SP floods were designed with low operational cost in mind and were tested in laboratory corefloods under reservoir conditions. Different injection water salinities were considered for practical field application. The handling and availability of injection water with a suitable composition has significant implications in CEOR projects. The SP design using produced brine with minimum water treatment is an attractive option for field commercial deployment. We considered different injection water salinities, surfactant molecules, and brine treatment requirements for several ASP and SP formulations and injection design strategies.ASP and SP corefloods recovered nearly all the remaining oil after waterflooding. The surfactant retention was lower for SP floods when brine with reduced concentration of Ca2+ and Mg2+ (hardness) was used. Both ASP and SP formulations were also tested for crude oil samples from different zones. A minimal adjustment in injection salinity was required for different oils with our surfactant formulations. Field implementation strategies were evaluated via numerical simulation. The effect of strong aquifer drive on SP performance was shown to be minimized with optimized injection/production strategies. SP was shown to be technically and economically an attractive candidate tertiary process.

Robust Nitritation of Anaerobic Digester Centrate Using Dual Stressors and Timed Alkali Additions.

Nitrogen is commonly removed from wastewater by nitrification to nitrate followed by nitrate reduction to N2. Shortcut N removal saves energy by limiting ammonia oxidation to nitrite, but nitrite accumulation can be unstable. We hypothesized that repeated short-term exposures of ammonia-oxidizing communities to free ammonia (FA) and free nitrous acid (FNA) would stabilize nitritation by selecting against nitrite-oxidizing bacteria (NOB). Accordingly, we evaluated ammonium oxidation of anaerobic digester centrate in two bench-scale sequencing batch reactors (SBRs), seeded with the same inoculum and operated identically but with differing pH-control strategies. A single stressor SBR (SS/SBR) using pH set-point control produced HNO3, while a dual stressor SBR (DS/SBR) using timed alkalinity addition (TAA) produced HNO2 (ammonium removal efficiency of 97 ± 2%; nitrite accumulation ratio of 98 ± 1%). The TAA protocol was developed during an adaptation period with continuous pH monitoring. After adaptation, automated TAA enabled stable nitritation without set-point control. In the SS/SBR, repeatedly exposing the community to FA (8-10 h/exposure, one exposure/cycle) selected for FA-tolerant ammonia-oxidizing bacteria (Nitrosomonas sp. NM107) and NOB (Nitrobacter sp.). In the DS/SBR, repeatedly exposing the community to FA (2-4 h/exposure, three exposures/cycle) and FNA (4-6 h/exposure, two exposures/cycle) selected for FA- and FNA-resistant AOB (Nitrosomonas IWT514) and against NOB, stabilizing nitritation.

The effect of sodium carbonate on reducing the interfacial tension of petroleum sulfonate

In current chemical flooding technology, surfactant and polymer (SP) rather than alkali, surfactant and polymer (ASP) flooding is preferred, because the addition of alkali in ASP flooding has been linked to environmental problems. However, in the absence of added alkali, the interfacial performance of petroleum sulfonate (PS) in SP flooding is greatly impaired. Therefore, an important task in SP flooding is to understand the interaction between PS and alkali in reducing interfacial tension (IFT), with the goal of finding a more eco-friendly alternative to alkali. In this study, PS was separated according to its composition: sodium PS, unsulfonated oil, inorganic salt and water. A comparison of the effects of Na2CO3, NaCl and ethanolamine on IFT showed that the electrolyte property of Na2CO3, rather than its alkalinity, played a major role in reducing the IFT. The unsulfonated oil was found to be an indispensable component of PS. A subsequent analysis showed that the unsulfonated oil and the hydrophobic chains of PS had similar carbon numbers, which explained the improved adsorption of PS at the oil-water interface. The oil-water partition coefficient and the minimum cross-sectional area of PS were also studied. The effect of NaCl on the oil-water partition coefficient was stronger than that of Na2CO3, and the effect of Na2CO3 on the minimum cross-sectional area was slightly stronger than that of NaCl. These results demonstrate the potential of NaCl to replace Na2CO3 in supporting the PS-mediated reduction of IFT in SP flooding.

Method for improving of activated sludge drying by the appropriate foaming pre-treatment

Due to the high viscosity and stickiness of dehydrated sludge, the combination of foaming pretreatment and drying process is an effective method to improve the drying performance of dehydrated sludge. In this study, alkali and industrial lignin fiber addition followed by mechanical whipping was employed for foaming the dewatered sludge. Using alkali alone as foaming agent, the optimal NaOH addition was found at 2.5 wt%, which was superior to adding CaO. Considering the maximum foaming efficiency, 2% industrial lignin fiber FH-300 collected as a conditioner and 1% NaOH was optimal. The foams in dewatered sludge were highly stable. The total number of bubbles of sludge with different densities had big differences. The diameters of bubbles concentrated on the range of 0.1 mm-0.3 mm.

New approach to consecutive CO oxidation and CO2 chemisorption using Li2CuO2 ceramics modified with Na- and K-molten salts

The addition of alkali carbonates to Li2CuO2 improved the CO oxidation and the subsequent CO2 with a high ratio of captured/released CO2. Materials modified with a single carbonate presented the best enhancement for the removal of both COX.