Acidic Waste Research Articles

An improved Hummers method to synthesize graphene oxide using much less concentrated sulfuric acid

The production of graphene oxide with less acid is beneficial to reduce the costs and lower the impact on the environment, but it is still a great challenge. In this work, a relatively simple, safe method for synthesizing graphene oxide with much less acid (decrease ∼40%) is proposed. With assistance of the heat absorbed from environment and reaction system, the temperature of reaction system of low acid can be well controlled. More interestingly, the graphite can be completely oxidized into graphite oxide by using much less acid, with lowering the production of high-concentration aqueous waste acid (> 1 mol/L, decrease ∼40%). A series of characterizations show that the prepared graphene oxide has similar yield and functional groups compared with that of using the conventional method. This work provides a safe and environmentally friendly choice for the large-scale production of graphene oxide and its derivative materials. Graphene oxide was synthesized by using much less concentrated sulfuric acid. The graphite can be completely oxidized into graphite oxide, with lowering the production of high-concentration aqueous waste acid (> 1 mol/L, decrease ∼40%).

Extraction Separation of Ti(IV) and Fe(II) Using D2EHPA from the Raffinate Obtained After Extraction of Scandium from Titanium Dioxide Waste Acid

Extraction Separation of Ti(IV) and Fe(II) Using D2EHPA from the Raffinate Obtained After Extraction of Scandium from Titanium Dioxide Waste Acid

Polyphosphate‐Grafted Fe3O4 Nanomagnets for the Removal of Trivalent Radionuclides from Acidic Nuclear Waste Solution

AbstractThe removal of radionuclides from nuclear waste solution is one of the biggest environmental challenges in today's world. In this aspect, polyphosphate grafted Fe3O4 nanomagnets (PPNMs) were investigated for its efficiency in removal of trivalent radionuclides from acidic nuclear waste solution. Various characterization techniques like XRD, FTIR, TEM and DLS were used to characterize these PPNMs, which showed successful formation of single phase, polyphosphate functionalized aqueous stable Fe3O4 nanostructure with average size ∼10 nm. The kinetics of sorption for Am(III) and Eu(III) by the PPNMs was found to be very fast with equilibrium being attained within ∼5 min. The sorption of both the radionuclides was following pseudo second order kinetic model. With increasing pH of the solution, the sorption efficiency of PPNMs for both the radionuclides was found to increase, whereas it decreased with increasing ionic strength of the medium. These observations clearly suggested that the sorption process proceeds through electrostatic interaction between the nanomagnets and trivalent radionuclides. Moreover, the PPNMs retained their sorption efficiency for at least 10 successive cycles when desorbed with 0.2 M HNO3. Thus, these magnetic nanosorbents can be used as highly effective, separable and reusable materials for removal of trivalent radionuclides from acidic nuclear waste solution.

Optimal performance of electrodialysis process for the recovery of acid wastes in wastewater: Practicing circular economy in aluminum finishing industry

This work aimed to apply electrodialysis (ED) for the recovery of diluted sulfuric acid (H2SO4) waste liquor generated at rinsing baths in the aluminum anodizing industry. A bench-scale ED process was used to recover acid and water from diluted waste acid liquors in the aluminum anodizing process. The optimal conditions and parameters defined in bench-scale studies were utilized to treat a real industrial acid solution. A bench-scale ED system was run continuously with a connected rinse water line of aluminum plating to concentrate diluted sulfuric acid for recovery. Industrial-scale studies confirmed that the produced concentrated acid and water solutions were of sufficient quality to be reused during the aluminum anodizing process. Besides, diluate characteristics allowed it to be reused as rinse water and reduced the effluent volume sent to the wastewater treatment plant by 90%. Electrodialysis treatment provided a near-zero pollutant discharge. Closed cycle water and acid usage loop were achieved for the aluminum galvanic process, which lessens the environmental and economic impacts of the process. Overall, electrodialysis presented a promising option for the aluminum industry.

Rare Earth Elements Recovery Using Selective Membranes via Extraction and Rejection.

Recently, demands for raw materials like rare earth elements (REEs) have increased considerably due to their high potential applications in modern industry. Additionally, REEs’ similar chemical and physical properties caused their separation to be difficult. Numerous strategies for REEs separation such as precipitation, adsorption and solvent extraction have been applied. However, these strategies have various disadvantages such as low selectivity and purity of desired elements, high cost, vast consumption of chemicals and creation of many pollutions due to remaining large amounts of acidic and alkaline wastes. Membrane separation technology (MST), as an environmentally friendly approach, has recently attracted much attention for the extraction of REEs. The separation of REEs by membranes usually occurs through three mechanisms: (1) complexation of REE ions with extractant that is embedded in the membrane matrix, (2) adsorption of REE ions on the surface created-active sites on the membrane and (3) the rejection of REE ions or REEs complex with organic materials from the membrane. In this review, we investigated the effect of these mechanisms on the selectivity and efficiency of the membrane separation process. Finally, potential directions for future studies were recommended at the end of the review.

Recovery of Ti from titanium white waste acid with N1923 extraction and leaching of low‐grade pyrolusite using raffinate

AbstractTitanium dioxide industry produces a large amount of titanium white waste acid every year. In this work, to make full use of and recover valuable components in titanium white waste acid, a processing for recovery of Ti from titanium white waste acid with N1923 extraction and leaching of low‐grade pyrolusite using raffinate was proposed. After a two‐stage countercurrent extraction, 99.93% Ti was extracted, while 6.51% Fe, .11% Mg, .06% Mn, and .08% Al were co‐extracted under N1923 concentration of 25% and phase ratio (O/A) of 2/1. The scrubbing efficiency of iron reached 98.53%, while the loss efficiency of titanium was only .94% with 1.5 mol/L sulfuric acid solution under the phase ratio of 1/1. Then, the Ti‐loaded organic phase could be effectively stripped by .8 mol/L ammonia water; the single‐stage stripping efficiency of titanium was 99.23%. Subsequently, the raffinate could be used for the extraction of manganese from low‐grade pyrolusite. The leaching efficiency of manganese was 99.39% at the S/L ratio of 48.00 g/L, leaching temperature of 50°C, and leaching time of 40 min. In addition, thermodynamic calculations revealed that the titanium extraction process by N1923 from titanium white waste acid was an exothermic reaction. The proposed approach is suitable for co‐recovery of titanium from titanium white waste acid and manganese from low‐grade pyrolusite.

The Recycling of Acid Wastewater with High Concentrations of Organic Matter: Recovery of H2SO4 and Preparation of Activated Carbon

Little work has been focused on the recycling of hazardous acid waste with high concentrations of organic matter from petroleum refining. This study developed an innovative, effective, and simple method for the recycling of acid waste that can successfully resolve this significant problem in industry. After parameter optimization, the optimal process is as follows. (1) Through heat treatment at 170 °C, liquid acid waste was transformed into solid; (2) by washing the solids, 70% by weight of sulfuric acid was recycled; and (3) the solid residue after washing was activated by alkali (NaOH or KOH) at an alkali and organic carbon ratio of 2:1, at a temperature of 650 °C for 60 min, producing superior-grade activated carbon with a specific surface area of 1378 m2/g, a pore volume of 0.5107 cm2/g, an iodine number of 1800 mg/g, and a methylene blue adsorption capacity of 240 mg/g. Thus, in this way, both waste sulfuric acid and organic impurities are turned into valuable resources, and no hazardous waste gypsum residues are generated. This method both reduces carbon emissions and recycles valuable resources, which is of important environmental and economic significance.

Preparation of Antimicrobial Iron Oxide Nanostructures from Galvanizning Effluent

Galvanization is the process of applying a protective zinc coating to iron or steel to prevent rusting. In the batch hot-dip galvanizing process, large amounts of wastes originate in liquid, solid and gaseous forms. Acidic waste containing iron and zinc ions is produced due to the cleaning of steel prior to zinc coating, which is considered the galvanizing acid waste. The galvanizing effluent used was collected from LTL Galvanizers Pvt. Ltd., Sapugaskanda, Sri Lanka, and converted into antimicrobial hematite (α-Fe2O3) nanoparticles. These nanoparticles were synthesized using a chemical precipitation method. X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) were used to characterize the nanomaterials produced. Two pathogenic bacteria and one pathogenic fungus were used to analyze the antimicrobial activity of the nanomaterials. All the samples showed excellent antibacterial and antifungal properties. And the material can inhibit the growth of both Gram-positive and Gram-negative bacteria. According to the SEM images, some of the hematite particles were around 100 nm in size or less, which confirms that the describing method is viable in synthesizing hematite nanostructures. As shown in the XRD, the major diffraction peak, located at 2θ of 35.617° (110) in addition to minor peaks at 24.87° (012), 33.07° (104), 42.08° (113), 51.18° (024), 53.52° (116) and, 57.46° (018) confirm the spinel structure of iron oxide (α-Fe2O3). The estimated average crystallite size of the nanomaterial is calculated to be 36.74 nm. The durability of the manufactured nanomaterial is excellent. This method is a time-efficient, environmentally friendly, cost-effective and industrially viable way to manufacture antimicrobial hematite (α-Fe2O3) nanomaterials from a galvanizing effluent.

A novel method for alumina preparation by electrotransformation AlCl3 solution under NH4Cl-catalyzed and CO2-injected conditions

As a refractory industrial solid waste, high-alumina fly ash is discharged into nature in large quantities, causing serious environmental harm. The extraction of valuable components, such as aluminum, from high-alumina fly ash has become a research hotspot at home and abroad. The shortcomings of traditional alumina extraction from high-alumina fly ash include long technological processes, large amounts of waste acid and alkali, and serious equipment corrosion. A novel method for alumina preparation by electrotransformation AlCl3 solution(EAS) under NH4Cl catalysis with injected CO2 has been proposed by Northeastern University. The process has advantages, such as short flow and no waste acid discharge. In this study, the influence of initial NH4Cl concentration in the cathodic chamber on solution pH, phase and morphology of electrotransformation products, phase, D(50) and D(90) of roasting products, and Al recovery rate were examined. Simultaneously, EAS was examined and compared with and without injected CO2, as well as EAS under NH4Cl catalysis with and without injected CO2. The results showed that, when the solution in the cathodic chamber was NH4Cl with CO2 injection, with electrotransformation time extension, pH increased slowly and the morphology of electrotransformation products were all rough and fluffy block structures. Increasing initial NH4Cl concentration effectively improved the product crystallization states, roasting products D(50) and D(90), and Al recovery rate.

Biochars Loaded Iron Phosphides and Cu Hybrides Deriving from Solid Waste and Waste Acids: An Efficient Catalyst to Eliminate Refractory Organic Pollutants from High-Salinity Pharmaceutical Wastewater

Biochars Loaded Iron Phosphides and Cu Hybrides Deriving from Solid Waste and Waste Acids: An Efficient Catalyst to Eliminate Refractory Organic Pollutants from High-Salinity Pharmaceutical Wastewater

An insight into the sequestration of tetra and hexavalent actinides by tri ethoxysilyl-amino-propyl-3-oxa-glutaramic acid (SAPOGA) functionalized titania.

Silyl-amino-propyl-3-oxa-glutaramic acid (SAPOGA) functionalized titania has been synthesized for highly efficient solid phase sequestration of thorium and uranyl ions from an aqueous acidic waste stream. The XRD pattern suggested that the grafting was performed on the anatase phase, leading to a rougher surface resulting in better interaction with actinides. The successful grafting of SAPOGA bridging was confirmed using spectroscopic methods. The Langmuir isotherm and the intraparticle diffusion-based kinetics model were found to be operative with sorption capacities of 231 mg g-1 and 458 mg g-1 and rate constants of 51 mg g-1 min-1 and 48 mg g-1 min-1 for U and Th, respectively. The entropy driven sequestration process was thermodynamically favourable (ΔGU = -6.0 kJ mol-1 and ΔGTh = -9.1 kJ mol-1) and endothermic in nature. The experimentally corroborated complexation pattern was assisted by density functional theory (DFT) calculations, which gave further insight into the metal-ligand interaction.

Selective recovery of Pb(II) from a waste electrolyte via ion flotation with iminodiacetic acid-functionalized graphene oxide as a nanocollector

In this work, iminodiacetic acid-functionalized graphene oxide (IDA@GO) is prepared and used as a nanocollector for enhancing and selectively recovering Pb(II) from a strongly acidic waste electrolyte via ion flotation. IDA@GO is characterized by Fourier transform infrared spectroscopy, zeta potential measurements and atomic force microscopy. The effects of pH, reaction time, cetyl trimethyl ammonium bromide (CTAB) dosage and aeration rate on the Pb(II) concentration and turbidity of the residual solution are examined systematically. The experimental results show that the adsorption capacity of Pb(II) on IDA@GO can reach 91.21 mg/g at pH 2. After froth flotation, the turbidity of the treated solution decreased to 0.55 NTU under the optimal CTAB dosage and aeration rate. In addition, as compared with GO, the relative selectivity coefficients of IDA@GO are up to 1.304, 1.471, 1.807 and 1.509 for Co(II), Ni(II), Zn(II) and Cd(II), respectively, thereby exhibiting better selectivity performance. Moreover, IDA@GO can be reused as a nanocollector in ion flotation and exhibits ideal regeneration performance. In addition, the recovery mechanism is found to proceed through Pb(II) adsorbing on IDA@GO by electrostatic attraction, ion exchange and surface complexation, with the addition of CTAB improving the hydrophobicity of Pb(II)-loaded IDA@GO flocs, thus achieving the recovery of Pb(II) via froth flotation.

An Efficient Process for Recovering Copper as Cuo Nanoparticles from Acidic Waste Etchant Via Chemical Precipitation and Thermal Decomposition: Turning Waste into Value-Added Product

An Efficient Process for Recovering Copper as Cuo Nanoparticles from Acidic Waste Etchant Via Chemical Precipitation and Thermal Decomposition: Turning Waste into Value-Added Product

Vanadium(IV) ions extraction in the aqueous two-phase system based on poly(ethylene glycol)

Vanadium has found wide applications in various industries: metallurgy, electronics, batteries, and others. This element, being dispersed, does not form its minerals and, therefore, is mined along the way. An alternative approach of vanadium extraction is to separate it from heavy oil, by flushing the oil with strong acids solutions and further hydrometallurgical processing. The existing methods of oil dehydration solutions processing for the vanadium extraction are not perfect - they do not meet the “green” chemistry principles. Thus, we investigated V(IV) ions extraction in the aqueous two-phase system (ATPS) based on poly(ethylene glycol) 1500 (16.3wt%) – NaNO3 (36wt%) – H2O. The dependences of V(IV) extraction efficiency on phases time contact, and dependences V(IV) distribution coefficients on salt phase acidity have been obtained. This system is shown to be a prospective solution for the vanadium(IV) recovery from acidic waste steams problem as it is possible to extract vanadium with an efficiency of more than 81.6% per one extraction step (the distribution coefficient of vanadium (IV) was 4.84).

Removal of Cu and Sb from Waste Acid Process of Copper Smelters for Minimizing Waste Generation

Removal of Cu and Sb from Waste Acid Process of Copper Smelters for Minimizing Waste Generation

Continuous kilogram-scale process for the synthesis strategy of 1,3,5-trimethyl-2-nitrobenzene in microreactor

1,3,5-trimethyl-2-nitrobenzene is a valuable synthetic intermediate with essential applications in the dyes industry. Because of poor micro-mixing and the large consumption of waste acid using the traditional reactor, the content of impurity and the yield of 1,3,5-trimethyl-2-nitrobenzene are not stable. Therefore, a continuous kilogram-scale process for the synthesis strategy of 1,3,5-trimethyl-2-nitrobenzene in microreactor was reported in this paper. Two microreactors and three pumps quickly assemble the microflow system. Mesitylene was first mixed with nitric acid and then combined with sulfuric acid under-designed experimental parameters. The effects of process parameters in the three synthetic strategies, including an organic solvent, temperature, molar ratio, flow rate, and sulfuric acid content, were systemically investigated. Based on the results of process parameter optimization, the production of 1,3,5-trimethyl-2-nitrobenzene at the kilogram level was achieved in a microreactor with two microreactors in series. Compared with the traditional batch reactor, sulfuric acid consumption was decreased by 7.6 times, and the reaction time was reduced from 4h to 60s. Compared with the synthesis methods reported in the literature, the two-step synthesis method proposed in this paper has better advantages in terms of reaction time, product purity, and conversion rate. It provides a new synthetic strategy for the industrial production of aromatic compounds by nitration reaction.

The neutralizing of Acidic Wastewater Produced From Trinitrotoluene (TNT) Factory by Rock granules

Acidic wastewater treatment for the TNT factory which located in the middle of the mountains is characterized by part of its nature with alkaline properties, which prompted the researcher to take advantage of it in the treatment of acidic water instead of caustic soda. Acidic waste water is originated from spent acid treatment building, nitration, purification building, drying and packing building in TNT factory. The objective of this study is to use treated Acidic water TNT Factory by rock granules. Acidic waste water is mixed together with rock granules lye after crushed process of these rocks. The results the pH value of water after neutralizing reaction showed a significant rise in pH from 1.20 to 7. 00. This is within the SSMO. These data included reduction in BOD from 30.00 to 7.00 mg/l which is also within the range of SSMO. The COD value of the acidic wastewater which is 65.00 mg/l to 11 mg/l which is also within the range of SSMO. The use of rock granules for treatment will save an amount 9.45kg/t of caustic soda per ton of product TNT product.

Preparation of Graphene Oxide/Cellulose Composites with Microcrystalline Cellulose Acid Hydrolysis Using the Waste Acids Generated by the Hummers Method of Graphene Oxide Synthesis.

The Hummers method is the most commonly used method to prepare graphene oxide (GO). However, many waste acids remain in the raw reaction mixture after the completion of this reaction. The aim of this study was to reuse these waste acids efficiently. In this study, microcrystalline cellulose (MCC) was directly dissolved in the mixture after the high-temperature reaction of the Hummers method. The residual acid was used to hydrolyze MCC, and the graphene oxide/microcrystalline cellulose (GO/MCC) composites were prepared, while the acid was reused. The effects of MCC addition (0.5 g, 1.0 g, and 1.5 g in 20 mL) on the properties of the composites were discussed. The structure, composition, thermal stability, and hydrophobicity of GO/MCC composites were characterized and tested by SEM, XRD, FTIR, TG, and contact angle tests. The results showed that MCC could be acid hydrolyzed into micron and nano-scale cellulose by using the strong acidity of waste liquid after GO preparation, and it interacted with the prepared GO to form GO/MCC composites. When the addition amount of MCC was 1 g, the thermal stability of the composite was the highest due to the interaction between acid-hydrolyzed MCC and GO sheets. At the same time, the hydrophobic property of the GO/MCC composite is better than that of the GO film. The freeze-dried GO/MCC composites are more easily dispersed in water and have stronger stability.

3D printed honeycomb cellular beams made of composite materials (plastic and timber)

The abundance of the waste materials of wood and plastic inspired the authors to explore the possibility of 3D printing the recycled materials as composite beams. This paper addresses the design, fabrication, and structural testing of 3D printed composite beams under 3-point bending. The authors believe that 3D printing of beams from timber waste and Polylactic Acid (PLA) is a state-of-the-art and has excellent potential to be transformed to state-of-the-practice in the construction industry. Beams with different compositions of materials and printing densities were designed, printed and tested to failure. This paper elaborates details of the design and printing of the beams, which then will be followed by detailed discussions as to how each beam reacts under flexural loading in terms of deformability, stiffness, strength-to-mass ratio, failure, and load-carrying capacity. General deformations of the specimens implied that the design of the specimens was quite successful in avoiding any premature failure. Large deflections of all specimens indicated that the shear strengthening performed effectively as the shear-vulnerable areas were not affected by the shear failure. The infill density affects the flexural capacity, which is obviously due to the amount of material present against loading. The capacity of the specimens with PLA at the top and bottom sections of the beams was higher than the equivalent beams with timber flanges. Overall, very promising results were obtained with a view to extending the idea into more advanced elements and techniques to develop various 3D printed structural elements towards the ongoing discussion on automation in the construction and prefabrication.

Rhodotorula toruloides: an ideal microbial cell factory to produce oleochemicals, carotenoids, and other products.

Requirement of clean energy sources urges us to find substitutes for fossil fuels. Microorganisms provide an option to produce feedstock for biofuel production by utilizing inexpensive, renewable biomass. Rhodotorula toruloides (Rhodosporidium toruloides), a non-conventional oleaginous yeast, can accumulate intracellular lipids (single cell oil, SCO) more than 70% of its cell dry weight. At present, the SCO-based biodiesel is not a price-competitive fuel to the petroleum diesel. Many efforts are made to cut the cost of SCO by strengthening the performance of genetically modified R. toruloides strains and by valorization of low-cost biomass, including crude glycerol, lignocellulosic hydrolysates, food and agro waste, wastewater, and volatile fatty acids. Besides, optimization of fermentation and SCO recovery processes are carefully studied as well. Recently, new R. toruloides strains are developed via metabolic engineering and synthetic biology methods to produce value-added chemicals, such as sesquiterpenes, fatty acid esters, fatty alcohols, carotenoids, and building block chemicals. This review summarizes recent advances in the main aspects of R. toruloides studies, namely, construction of strains with new traits, valorization of low-cost biomass, process detection and optimization, and product recovery. In general, R. toruloides is a promising microbial cell factory for production of biochemicals.