Water Washing Process Research Articles

Water-Based Recycling Process of FTO/SnO2 Substrate for Sustainable Perovskite Solar Cell Technology.

Fluorine-doped tin oxide (FTO) substrate is an important and expensive component in perovskite solar cells (PSCs), which accounts for up to 40% of a typical PSC raw material cost. In this study, we investigated the recyclability of SnO2/FTO in PSCs by washing the spent PSCs using different solvent such as dimethylformamide (DMF), dimethylsulfoxide (DMSO), acetone, water, and acetone/water mixture. Characterisation of properties of the SnO2/FTO substrates recovered from the PSCshow the surface wettability of SnO2/FTO is largely unchanged with water washing while a higher hydrophobicity is obtained with organic solvent washing. Comparison of electronic properties of the SnO2/FTO substrate shows a downward shift of the conduction band by 180 meV with water washing, creating favourable energy alignment with adjacent perovskite for efficient interfacial charge injection. Consequently, PSCs using the water-based recycled SnO2/FTO substrates produced a high power conversion efficiency (PCE) of 19.33% which is comparable to the device using fresh SnO2/FTO substrate (PCE = 19.85%). Furthermore, we demonstrated that the water washing process could retain property of SnO2/FTO substrate for decent PSC performance up to four recycling cycles. This study opens new avenues towards recycling of valuable FTO substrates in PSCs for increased sustainability and cost-effectiveness.

Study on hydration and heavy metal leaching of washed MSWI FA as a green cementitious material

Despite municipal solid waste incineration fly ash (MSWI FA) being classified as hazardous waste, there is a consensus on its significant potential for resource utilization. The high content of soluble chlorides in MSWI FA not only limits its co-disposal in cement kilns but also hinders its application in the field of construction materials. The research aimed to investigate the viability of MSWI FA as a binding material in the construction engineering field. Through examining the impact of liquid/solid ratio and pH levels on the chemical composition of MSWI FA during the washing procedure, the study delved into the mechanisms affecting hydration and the characteristics of heavy metal contamination before and after washing pretreatment. The results indicate the feasibility of developing MSWI FA into construction engineering materials. The liquid/solid ratio is a significant factor affecting the removal of chlorides, with an optimal ratio of 30. pH plays a crucial role in the mineral composition during the water-washing process of MSWI FA. An acidic environment can remove a higher proportion of chlorides, while an alkaline environment can form more calcium salts. The compressive strength of pure MSWI FA at 28 days is 3.92 MPa, which can be increased by 0.99 MPa after washing. The washed MSWI FA not only exhibits heightened reactivity but also demonstrates reduced leaching concentrations of heavy metals, and its leaching toxicity was much lower than the safe landfill threshold. Therefore, MSWI FA, after washing, is a very promising alternative material for construction engineering.

A green and low-cost approach to recover graphite for high-performance aluminum ion battery cathode

The recovery of spent graphite (SG) from lithium-ion batteries (LIBs) has been neglected due to its relatively low value and the lack of effective recovery methods. In this study, a green and cost-effective water washing process was used to recycle the spent graphite of LIBs anode, and the recovered graphite (RG) was used as the cathode material of aluminum ion batteries (AIBs). The RG retained the integrated graphite structure after the water washing process, showing a slightly enlarged interlayer spacing. When used as a cathode material for AIBs, it exhibits better electrochemical performance than commercial artificial graphite. At a current density of 50 mA g−1, the RG shows a high specific capacity of 95.2 mAh g−1. At a high current density of 2000 mA g−1, the specific capacity still maintains 51 mAh g−1, demonstrating excellent rate performance. Meanwhile, the average specific capacity of 72.5 mAh g−1 was steadily cycled for 10,000 cycles at a current density of 1000 mA g−1, showing excellent cycle performance. This work provides a novel approach to the high-value-added application of spent graphite from lithium batteries and a development of high-performance graphite cathode materials for AIBs.

Recovery of rare earth elements from rare earth molten salt electrolytic slag via fluorine fixation by MgCl2 roasting

Rare earth fluoride molten-salt electrolytic slag (REFES) is a precious rare earth element (REE) secondary resource, and considerable amounts of REEs exist in REFES as REF3; they are difficult to dissolve in acid or water and impede efficient REE extraction. In REFES recovery, the REF3 species in REFES are usually transformed into acid-soluble rare earth compounds by NaOH roasting or sulfating roasting and then extracted by acid leaching. Moreover, the fluorides in REFES are released as HF gas in the roasting process or enter the liquid phase during the water washing process; both of these processes cause fluorine pollution. Fixing the fluorine into the solid slag provides a way to avoid fluorine pollution. In this study, a novel method was proposed to extract REEs from REFES via MgCl2 roasting followed by HCl leaching. Thermodynamics calculations and thermogravimetry‒differential thermal analyses (TG-DTA) were conducted to investigate the reactions occurring in the roasting process. First, MgCl2 reacts with the REF3 and RE2O3 to form RECl3 and REOCl, respectively. Second, the RECl3 absorbs water and forms RE(OH)3. Third, MgCl2·6H2O is gradually dehydrated to MgCl2·2H2O and reacts with REF3 and RE(OH)3, and REOCl, MgF2 and MgO are formed. Through HCl leaching, the REOCl in the roasting products is leached by HCl acid, while fluoride remains in the solid slag as MgF2. The optimum experimental conditions are as follows: mass ratio of MgCl2 to REFES of 30%, roasting temperature of 700 °C, roasting time of 2 h, hydrochloride acid concentration of 4 mol/L, leaching time of 2 h, leaching temperature of 90 °C and leaching L/S ratio of 20:1. The efficiencies for total leaching of the REEs, La, Ce, Pr, and Nd are 99.13%, 99.20%, 98.42%, 99.38%, and 99.08%, respectively. Moreover, the concentration of fluoride in the leaching solution is 2.191 × 10−6 mol/L. This method has a short process flow with low reagent costs, and the problem of fluoride pollution from REFES recovery is solved; thus, our study has great industrial application potential.

Mechanism of the denitrification of secondary aluminum dross (SAD) during water leaching with delayed addition of a low dosage of sodium hydroxide

Secondary aluminum dross (SAD) has been identified as a hazardous waste because it contains refractory AlN, fluoride, and other salts. Considering that Al(OH)3 produced during the hydrolysis of AlN in SAD hinders spontaneous AlN hydrolysis, which is amplified by the partial embedment of AlN in other oxide phases present in SAD particles, the complete removal of AlN from SAD is difficult. Herein, we propose a new catalytic hydrolytic denitrification process of SAD, which requires a low additive dose. By changing the time at which the additive (NaOH) was added to the SAD slurry, the proportion of nitrogen removed from SAD was increased. The additive (NaOH) reacted with Al(OH)3, thereby mitigating its hindering effect on spontaneous AlN hydrolysis and facilitating the complete hydrolysis of the semi-encapsulated AlN in SAD particles. Concurrently, the reaction between NaOH and Al2O3 and SiO2 phases present in SAD was mitigated, resulting in the maximal retention of residual materials (phases other than Al resources) in the solid phase. A SAD denitrification efficiency of 99.0% was achieved under optimal processing conditions (T = 95 °C, t = 240 min, Liquid-to-solid ratio = 6:1, stirring speed = 400 rpm, and the addition of 7 wt% NaOH at 0.5 h), and a slightly lower efficiency of 98.2% was achieved when 50% lower amount of NaOH (3 wt%) was used. Thus, approximately 50% less additive is required for nitrogen removal from SAD, relative to that used in traditional catalytic water-washing processes.

Undesired films with brilliant whiteness produced from a transparent amorphous polymer solution during room temperature evaporation or water washing

AbstractDuring the use, storage, or cleaning of polyetherimide (PEI) solutions, undesired white films often appear. In this study, equivalent experiments of PEI solutions involving room temperature evaporation and solvent exchange with water are conducted to simulate their air exposure and water washing processes, respectively. Specifically, we focus on investigating the phenomenon and mechanism of white appearance in their films from room temperature evaporation with a cellular‐like porous structure and solvent exchange films that exhibit a finger‐like porous structure. Results obtained from FE‐SEM, UV–Vis spectroscopy, and Datacolor reflectance spectrophotometer indicate that both types of porous structures exhibit long‐range disorderliness, leading to multiple scattering of incident light and high reflectance across the visible light spectrum resulting in a white appearance. Furthermore, due to different structures caused by phase separation, mechanical properties of solvent exchange films are significantly inferior compared with those of films from room temperature evaporation. Finally, we verify the universality of these mechanisms for white film formation in PEI through experiments using PS and PMMA. This study provides insights into efficient utilization of polymer solutions and offers new strategies for biomimetic preparation of white films.Highlights White cellular‐like porous films were prepared by solvent evaporation method. White finger‐like porous films were produced through solvent exchange by water. Multiple scattering caused by above porous structures led to white appearance. Finger‐like porous films with nanosphere as the basic scatter unit had a luster. Universality of both white formation mechanisms was verified by PMMA and PS.

Industrialized fine physical regeneration process and economic benefit assessment for recycling waste HDPE containers

The production of waste HDPE containers is enormous, and its recycling and utilization is an inevitable trend to achieve sustainable social development. However, the engineering practice of recycling waste HDPE containers is still lacking. This study provides a detailed explanation of the principles of fine recycling for waste HDPE containers, and develops a set of physical regeneration processes. By combining visual recognition assisted sorting, alkali hot water washing, physical sorting, and regranulation processes, high-quality regenerated HDPE particles are prepared. Meanwhile, various real data (sample size 50–100) of the production line and products are tracked, statistically analyzed. The results show that regenerated HDPE particles have good physical properties, the ratio of HDPE particles containing aluminum foil and multicolored impurities are extremely low, and the ratio of HDPE particles containing black spots (d＞0.1 mm) is less than 1.61 × 10−2 wt% (mean). Economic benefit analysis shows that the gross profit of recycled HDPE particles is USD $312.05 per ton. The above conclusions prove the feasibility and progressiveness of this process for the regeneration of waste HDPE containers. Meanwhile, this study provides engineering technical guidance for the large-scale fine recycling and regeneration of waste HDPE containers.

Study on dechlorination salt characteristics of pickling sludge by a water-washing process.

Steel hydrochloric acid pickling sludge (SHPS), containing the heavy metals Fe, Zn, and Ni and a high chloride salt content, is considered a hazardous solid waste. With the gradual reduction of high-grade metal mineral resources such as Fe, Zn and Ni, it is particularly urgent to recycle valuable metals such as Fe, Zn and Ni in solid waste SHPS in order to realize the resource utilization of SHPS and reduce the environmental harm caused by SHPS. In addition, SHPS usually contains different amounts of alkali chloride, which will have a serious adverse impact on the subsequent extraction and smelting process of Fe, Zn and other metals. Therefore, the removal of chloride plays an important role in the resource utilization of valuable metals in SHPS. Thus, in this study, the effects of water washing dechlorination process parameters such as liquid-solid (L/S) ratio, SHPS particle size, washing time and washing frequency on the chloride removal rate were investigated. The best experimental parameters of SHPS washing were obtained. At the same time, the microscopic morphology and crystal phase composition of SHPS before and after washing were explored. The results showed that the optimized conditions were as follows: room temperature, a L/S ratio of 3 : 1, an SHPS particle size of 100 mesh, and 10 min of water washing, repeated two or three times; under these conditions, the removal rate of Cl, Na, Ca, K, Mg, and S reached 96.64-99.68%, 97.38-99.89%, 36.40-60.37%, 49.11-54.82%, 39.18-40.22%, and 36.98-42.13% respectively. The contents of Cl, K, and Na in filter residue (FR) meets the requirements in GB/T 36144-2018 and GB/T 32545-2016. Conversely, the contents of Fe, Zn, Mn and Ni in the FR are enriched, which is more conducive to the subsequent resource utilization of SHPS. The scanning electron microscope (SEM) image shows the particle size of the FR particles is reduced after washing. The X-ray diffractometer (XRD) results proved that the chlorine salt content in the FR after washing was significantly reduced, the diffraction peaks of Al2O3 appeared in the FR, and the diffraction peak intensity of CaCO3, Fe2O3 and SiO2 increased.

Green lignocellulosic superadsorbent for superior Pd(II) removal and cascade catalytic conversion

In this study, a lignocellulosic-based adsorbent with excellent adsorption capacity for palladium and can be used for upcycling as an eco-friendly catalyst was prepared. The palladium adsorption performance of the lignocellulosic-based adsorption material was improved by 6 times compared to that of kraft lignin before the cationization modification process using polyethyleneimine. The prepared cationized lignin was introduced into a cellulose dissolution-regeneration process to be fabricated into a bead-type adsorbent, and through a cross-linking reaction using citric acid, a natural cross-linking agent, structural stability in contaminated water was achieved and adsorbent recovery and reuse were facilitated. As a result of the adsorption isothermal study, the maximum monolayer adsorption capacity for palladium of the regenerated cellulose beads containing cationized lignin was 212.5 mg/g. Palladium was recovered and reused from the beads by reducing Pd(II) to Pd(0) using the cationized lignin-containing regenerated cellulose beads as the catalyst. After reduction, Pd(0) present on and inside the beads successfully promoted the hydrogenation reaction that reduces 4-nitrophenol to 4-aminophenol with a conversion rate of 98 %. In addition, when reused 5 times after a simple water washing process, a conversion rate of 96 % or more was maintained, and high reuse catalyst efficiency was exhibited.

Remediation of heavily PAHs-contaminated soil with high mineral content from a coking plant using surfactant-enhanced soil washing

This study investigated the effectiveness of various surfactants at different concentrations in removing high concentrations of polycyclic aromatic hydrocarbons (PAHs) from soil with high mineral content, focusing on the impact of surfactant treatment on the mobility of the residual PAHs in soil. The results revealed that the cationic surfactant (CTMAB) inhibited removal of PAHs in the whole tested concentration range of 0.1–8 g/L. In contrast, the non-ionic and anionic surfactants (Triton X-100 and SDBS) significantly enhanced removal of PAHs as their amendment concentrations reached 2 g/L and above. Triton X-100 exhibited steadily increased efficacy with increasing amendment concentrations and maintained favorable solubilization capability when continuously amended, making it the preferable choice for remediating PAHs-contaminated soil. Surfactant and water washing processes altered soil physicochemical properties by removing some clay minerals (e.g., faujasite) and organic matter that can bind or sequester PAHs, potentially increasing their extractability and bioavailability in the washed soil, thereby posing higher ecological risks compared to the original one. Although soil washing decreased retention of the remaining PAHs in soil, it did not significantly impact PAHs release from soil by flowing water. These findings provide insights into the long-term effectiveness and ecological impacts of surfactant-enhanced washing as a potential remediation technique for PAHs-contaminated soil.

A LABORATORY MODEL FOR THE TWO-PHASE FLOW CONTAMINANT TRANSIENT IN MULTI-POROUS MEDIA

The environmental behavior of rock and oil pollutants in soil has long been a focus of environmental protection research. In this research, a laboratory model was established to study the oil pollutant transfer process in two stages. Two samples from porous media of sandy soil and agricultural soil (organic) were used with oil as a pollutant. The oil is pumped through a system consisting of two pipes with a length of 4 m and a diameter of 0.07 m. Each pipe is assigned to a specific type of soil. The results showed that the organic soil needs a long time for the pollutants to travel over greater distances, while the sandy soil showed its ability to absorb and drain the pollutants and get rid of them faster. However, it was also found that both soils contain a small percentage of the pollutant after the water washing process, which lasts for more than (5 hours). The remaining oil percentage is estimated at about (0.1 ml), which is a very small percentage, and it is possible to get rid of it by increasing the washing time. It was found that the physical properties of the soil such as permeability and porosity have a significant effect on slowing down the speed of the pollutant and its transmission through the porous medium.

Preliminary Results of Innovative Two-Stage Torrefaction Technology Applied for Thermochemical Treatment of Sunflower Husk

This article proposes an innovative two-stage technology for biomass torrefaction generating high-quality biochar, more specifically biocoal, as solid fuel, and offering a promising solution to the challenges posed by the combustion of biomass. In particular, the higher quality of biochar as solid fuel reduces the build-up of unmanageable deposits on fired surfaces, as these deposits inhibit heat transfer and reduce the efficiency of biomass boilers. The proposed two-stage technology involves torrefaction in a hearth-type reactor at temperatures up to 250 °C, followed by a subsequent stage of cooling achieved through washing with water. The two-stage torrefaction technology is integrated within a vertical hearth reactor vessel composed of three superimposed trays serving for biomass input, torrefaction, and water washing combined with biomass cooling, respectively. Upon contact with torrefied biomass, cooling water turned into water vapor; hence, eliminating the requirement for subsequent biomass separation and drying. The system was tested on sunflower husk, and results showed a reduction in the content of problematic elements such as alkali metal chlorides or sulfur compounds in biochar ash, suggesting lower corrosion rates of convective heating surfaces of the boiler under ash sediments. It is hypothesized that, while water exited hot biomass in the form of water vapor instead of liquid water, as is typically the case in water-washing processes, a share of undesirable elements may still have been removed from biomass through vaporization, without necessitating any additional process for ash removal. Hence, the index values calculated according to the chemical analysis of biomass ash suggested that sunflower husk biochar (biocoal) resulting from the proposed two-stage torrefaction process may display fuel characteristics similar to biomasses whose combustion ash may form reduced levels of deposits on boiler surfaces. Therefore, the proposed technology holds the potential to improve solid fuel characteristics of biomass, targeting enhanced efficiency and sustainability of biomass-fired power plants.

Elaborating the mechanism of lead adsorption by biochar: Considering the impacts of water-washing and freeze-drying in preparing biochar

This paper examined the impacts of different pretreatments on the characteristics of biochar and its adsorption behavior for Pb2+. Biochar with combined pretreatment of water-washing and freeze-drying (W-FD-PB) performed a maximum adsorption capacity for Pb2+ of 406.99 mg/g, higher than that of 266.02 mg/g on water-washing pretreated biochar (W-PB) and 188.21 mg/g on directly pyrolyzed biochar (PB). This is because the water-washing process partially removed the K and Na, resulting in the relatively enriched Ca and Mg on W-FD-PB. And the freeze-drying pretreatment broke the fiber structure of pomelo peel, favoring the development of a fluffy surface and large specific surface area during pyrolysis. Quantitative mechanism analysis implied that cation ion exchange and precipitation were the driving forces in Pb2+ adsorption on biochar, and both mechanisms were enhanced during Pb2+ adsorption on W-FD-PB. Furthermore, adding W-FD-PB to Pb-contaminated soil increased the soil pH and significantly reduced the availability of Pb.

Effect of artificial formaldehyde treatment on textural quality of fish muscles and methods employed for formaldehyde reduction from fish muscles

The influence of treatment of three different concentrations of formaldehyde on fish muscles textural quality was determined using spectrophotometric and reverse phase high-performance liquid chromatography (RP-HPLC) methods. The experimental fish treated with 1, 5 & 10 % formaldehyde for 5 min and as a result, the residual content was enhanced to almost 7, 11 and 15 times respectively. The hardness and chewiness of fish muscles increased with increase in formaldehyde concentration and the values increased by 80 and 121 % respectively in the fish treated with 10 % formaldehyde. In order to reduce formaldehyde content in fish, formaldehyde-treated fish was washed in running tap water, saline water and tepid water separately for a period up to 30 minutes and thereby the content got reduced to the acceptable label in 20, 20, and 10 min respectively. Similarly, treated fish was fried for five minutes and content was reduced to acceptable limits. Overall, this study could establish that formaldehyde treatment not only reduced bacterial load but also improved the textural properties of the fish muscles, creating the impression that the fish is fresh. Tepid water washing and frying process were effective in reducing formaldehyde content in fish muscles.

Improve toxicity leaching, physicochemical properties of incineration fly ash and performance as admixture by water washing

Incineration fly ash is a hazardous solid waste with the risk of heavy metal leaching and dioxin overload. A large amount of chloride limits its application in the cement industry. The water-washing process can enhance resourceization of waste in the cement industry. In this paper, the effects of water washing on the physicochemical properties of incineration fly ash, its toxic leaching characteristics, and its performance as a cement admixture were investigated. The results showed that water washing could remove more than 90% of chlorine and some soluble substances, However, in the water washing process, heavy metals and dioxins could accumulate, and heavy metals might be leached from raw and washed ash. In cement preparation, washed ash could reduce the water requirement and prolong the setting time compared with the cement prepared by raw ash, meet the requirement of >42.5 MPa at <15% and improve the mechanical properties of cement at 5%. Washed ash and raw ash could promote cement hydration, during which, however, Friedel salts generated. Incineration fly ash could improve the pore structure of cement and enhance its mechanical properties. Cement could solidify heavy metals well, and there was no risk of heavy metal leaching. Water washing was unable to remove dioxins. Thus, to reuse the water-washed incineration fly ash as a resource, it is necessary to dispose of dioxins and chlorides in it.

Dynamic Changes in Volatiles, Soluble Sugars, and Fatty Acids in Glutinous Rice during Cooking.

Cooking is an important process before rice is consumed and constitutes the key process for rice flavor formation. In this paper, dynamic changes in aroma- and sweetness-related compounds were tracked during the entire cooking process (including washing with water, presoaking, and hydrothermal cooking). The volatiles, fatty acids, and soluble sugars in raw rice, washed rice, presoaked rice, and cooked rice were compared. After being washed with water, the total volatiles decreased while aldehydes and unsaturated fatty acids increased. Meanwhile, oligosaccharides decreased and monosaccharides increased. The changes in fatty acids and soluble sugars caused by the presoaking process were similar to those in the water-washing process. However, different changes were observed for volatiles, especially aldehydes and ketone. After hydrothermal cooking, furans, aldehydes, alcohols, and esters increased while hydrocarbons and aromatics decreased. Moreover, all fatty acids increased; among these, oleic acids and linoleic acid increased most. Unlike with washing and presoaking, all soluble sugars except fructose increased after hydrothermal cooking. Principal component analysis showed that cooked rice possessed a volatile profile that was quite different from that of uncooked rice, while washed rice and presoaked rice possessed similar volatile profiles. These results indicated that hydrothermal cooking is the pivotal process for rice flavor formation.

A General Method for the Large‐Scale Preparation of Multifunctional Magnetic Sm‐Fe/Co Nanomaterials

AbstractA general method is reported to prepare single crystal Sm‐Fe/Co nanoparticles (NPs) on a tens of grams scale without Ca‐reduction process. The preparation starts with the fabrication of size‐controllable SmH2 NPs via evaporation‐condensation route, and then Co NPs produced from solvothermal approach are assembled with SmH2 to form SmH2/Co nanocomposites, which are directly annealed at 700 °C for 1.5 h, yielding 160 ± 15 nm SmCo5 single crystal NPs. Compared with conventional Ca‐reduction process, the method allows more low annealing temperature, and avoids the employment of Ca and the corresponding water washing process, leading to the stable SmCo5 NPs without obvious oxidation. The SmCo5 NPs show a large coercivity of 35.4 kOe and high saturated magnetic moment of 86.2 emu g−1. Furthermore, the method is extended to synthesize Sm2Fe17 NPs, which exhibits good electromagnetic wave absorption performance with a minimum reflection loss of −45.2 dB and the effective absorption bandwidth of 5.61 GHz (9.22–14.83 GHz) at 1.2 mm. More importantly, the method is very suitable to large‐scale synthesis. One synthesis can generate ≈ 42.25 g of SmCo5 or 43.30 g of Sm2Fe17 NPs, which demonstrates a promising novel strategy to scale up preparation of RE‐Co/Fe NPs for multifunction magnetic applications.

Release mechanism of impurity potassium in molybdenum concentrate treatment process

AbstractThe kinetic characteristics and mechanism of potassium release in the molybdenum concentrate treatment process were studied by kinetic analysis and analytical techniques such as SEM−EDS, MLA and ICP. The results show that the first-order kinetic model is the best kinetic model of potassium release in the water washing and ammonia leaching process. Potassium is present in molybdenum concentrate in the form of soluble potassium ions and four potassium minerals. During the roasting process of molybdenum concentrate, some muscovite decomposed into orthoclase, while other muscovite combined with impurity metal elements to form anandite. Furthermore, the transformation of muscovite to orthoclase could be effectively inhibited by the rapid cooling of molybdenum calcine. The results could provide a basis for reducing potassium content in ammonium molybdate products.

Effect of pH-Shifting Process on the Cathepsin Activity, Muddy Off-Odor Compounds' Content and Gelling Properties of Isolated Protein from Silver Carp.

Silver carp (Hypophthalmichthys molitrix) is a potential source for making surimi products. However, it has the disadvantages of bony structures, high level of cathepsines and muddy off-odor which is mainly caused by geosmin (GEO) and 2-methylisoborneol (MIB). These disadvantages make the conventional water washing process of surimi inefficient (low protein recovery rate, and high residual muddy off-odor). Thus, the effect of the pH-shifting process (acid-isolating process and alkali-isolating process) on the cathepsins activity, GEO content, MIB content, and gelling properties of the isolated proteins (IPs) was investigated, comparing it with surimi obtained through the conventional cold water washing process (WM). The alkali-isolating process greatly boosted the protein recovery rate from 28.8% to 40.9% (p < 0.05). In addition, it removed 84% GEO and 90% MIB. The acid-isolating process removed about 77% GEO and 83% MIB. The acid-isolated protein (AC) displayed the lowest elastic modulus (G'), the highest TCA-peptide content (90.89 ± 4.65 mg/g) and the highest cathepsin L activity (65.43 ± 4.91 U/g). The AC modori (60 °C for 30 min) gel also demonstrated the lowest breaking force (226.2 ± 19.5 g) and breaking deformation (8.3 ± 0.4 mm), indicating that proteolysis caused by the cathepsin deteriorated the gel quality of AC. The setting (40 °C for 30 min) considerably increased the breaking force (386.4 ± 15.7 g) and breaking deformation (11.6 ± 0.2 mm) of the gel made from the alkali-isolated protein (AK) (p < 0.05). In AC and AK gel, a clearly visible cross-linking protein band with a molecular weight greater than MHC was seen, demonstrating the presence of endogenous trans-glutaminase (TGase) activity, that improved the gel quality of AK. In conclusion, the alkali-isolating process was an effective alternative method for making water-washed surimi from silver carp.

Study on Three-Stage Counter-Current Water Washing Desalination Characteristics and Mechanism of High Chlorine Waste Incineration Fly Ash

The high chloride content of municipal solid waste incineration (MSWI) fly ash and hazardous waste incineration (HWI) fly ash has considerably affected their disposal. This study focused on investigating the three-stage counter-current (TSC) water-washing process to reduce the chlorine content efficiently under the premise of low water consumption. The liquid–solid ratio (LSR) and washing time were investigated, a chloride migration model was established, and the characteristics of the water-washing solution (WWS) and washed fly ash were investigated. The results showed that the dechlorination effect of TSC washing could reach more than 99% in a low liquid–solid ratio (LSR) of 2–4 kg/L. The most appropriate LSR and washing time were found to be around 3:1 L/kg and 15 min per stage, respectively. The concentration of Cl− in WWS reached over 90 g/L, which is very high among industrial saline wastewater. Some heavy metals were also contained in the WWS, and lead was the main heavy metal, followed by zinc, copper, and arsenic. The concentration of WWS of different stages was calculated by a model, and the transfer characteristic of chloride was strongly related to the mass balance between the liquid contained in the solid–liquid separation residue (SR) and the separated liquid. After washing, due to the dissolution of soluble salt, the specific surface area of fly ash increased, and thus the absorption ability of the washed fly ash was greater than the raw one. This study provides a washing condition reference for highly chlorinated fly ash, the basic data of WWS, and the chloride migration model that is a preliminary calculation method to improve the water-washing process.