Methylene Blue Value Research Articles

Evaluating the properties of zinc production wastes as filler and their effects on asphalt mastic

This study evaluated four types of zinc production waste and limestone powder to be used as filler in asphalt mixtures. The properties of the fillers, asphalt mastic and mixtures made by the fillers were investigated. Only the results for fillers and mastics are provided. The physical and chemical properties and morphology of waste fillers, namely cobalt cake, leach cake, nickel cake, and zinc ash, as well as the limestone powder, as control filler, were examined. The moisture content, particle and bulk density, methylene blue value (MBV), Rigden voids (RV), pH, chemical compositions, morphology, hydrophobicity, size distribution, solubility in water, and specific surface area of the fillers were evaluated. Also, using a constant volumetric filler to binder ratio, asphalt mastics were made and their softening point, ductility, penetration grade and rheological properties were measured and compared with neat binder. Evaluation of the properties of fillers showed that the fillers can be potentially used in asphalt mixtures. Zinc ash had comparable and even better properties than the control filler. In terms of hydrophobicity, solubility in water and moisture content, the best performance belonged to zinc ash, followed by limestone, nickel, cobalt, and leach cake, respectively. Leach and cobalt cake showed to be hydrophilic fillers. The lowest MBV was found for the zinc ash, followed by limestone, nickel, leach and cobalt cake. The highest RV was found for the leach cake, and lowest for zinc ash filler. The fillers have different levels of stiffening effect on the mastic. In terms of temperature susceptibility using the softening point test results, the lowest sensitivity was obtained for zinc ash followed by cobalt cake, leach cake, limestone, and nickel cake. However, penetration and DSR test results revealed that the highest stiffening effect was obtained using zinc ash followed by cobalt cake, nickel cake, limestone, and leach cake. The stiffening effect of the fillers can be described by the morphology of filler particles; however, RV cannot be directly related to the stiffening effect of the fillers.

Synthesis of a cleaner potassium hydroxide-activated carbon from baobab seeds hulls and investigation of adsorption mechanisms for diuron: Chemical activation as alternative route for preparation of activated carbon from baobab seeds hulls and adsorption of diuron

Lignocellulosic agricultural residues are worldwide used for the production of activated carbons with purpose of eliminate a large range of pollutants such as diuron, a very persistent herbicide found in streams. This work studies the adsorption of diuron in aqueous solution on two different activated carbons, a commercial activated carbon and a prepared one. Activated carbon has been produced from seed hulls of baobab (Andansonia digitata), as a valorization pathway for this waste. Precursors have been impregnated with potassium hydroxide and then carbonized under nitrogen flow. The porous structure of the carbon has been determined by methylen blue adsorption, iodine adsorption and nitrogen adsorption-desorption. The BET surface areas of the produced carbon was 1086 m2·g‒1 with an iodine and methylene blue values of 1854.2 mg·g−1 and 26.66 mg·g−1 respectively. Batch removal kinetics of diuron has been studied at 5, 13 and 20 ppm initial concentrations on the two activated carbons in a reconstituate solution. The results showed that adsorption of diuron can be modelled by Langmuir isotherm with a maximal adsorption capacity of 65.7 mg·g−1 for baobab carbon and 151.8 mg·g−1 for commercial activated carbon at 120 min equilibrium time. Speudo-second order reaction fits well with data collected during adsorption of diuron on carbons studied. Thus, Baobab seed hulls can be considered as good precursors for preparation of activated carbon with high specific surface area.

Correlation between Plasticity Index and Methylene Blue Value to Determining Soil Classification

Most soil classification systems developed for geotechnical engineering purposes are based on simple index properties such as grain size distribution and plasticity. In Indonesia, the use of the methylene blue value, VBS, is still rarely used, compared to Atterberg limits that commonly used to determine the value of the plasticity index, PI. Therefore, this study aims to gain a correlation between PI and VBS. Coarse-grained soil with fines (clay and silt) contents varies from 12.36% to 29.45% are used of this study. The linear correlation between PI and VBS produces a linear equation with a coefficient of determination, R2 = 0.854 for 0.62 < VBS < 2.39. The PI obtained from the correlation to VBS that combined with the sieve analysis results can then be used for soil classification based on the Unified Soil Classification System (USCS).

Quantitative evolution of the petrophysical properties of andesites affected by argillic alteration in the hydrothermal system of Petite Anse-Diamant, Martinique

The evolution of the petrophysical properties of rocks induced by hydrothermal alteration is often considered qualitatively by sorting the hydrothermal alterations encountered from low to high intensity, depending on the identified mineral paragenesis. In this paper, we studied the evolution of three different petrophysical properties (connected porosity, permeability and electrical conductivity) as a function of the argillization degree of andesites affected by argillic alteration identified in the caprock formation of the Petite Anse-Diamant hydrothermal system in Martinique. These petrophysical measurements were supplemented by quantitative mineral evaluation via scanning electron microscopy (i.e., the Quantitative Evaluation of Minerals by Scanning electron microscopy or the QEMSCAN® method), connected porosity mapping using 14C-PMMA method and measurements of methylene blue (MB) values and structural water proportions (H2O+). In the series of rocks investigated, an increasing trend of clay mineral abundances (montmorillonite and kaolinite) from 5.68 to 37.56% was revealed by the QEMSCAN® method. Based on the quantitative results, the structural water proportions were used as a proxy of argillic alteration progression. Comparison between the mineral maps provided by the QEMSCAN® system and connected porosity mapping observed in autoradiographs using 14C-PMMA method revealed a good correlation with clay mineral phases, dissolution vugs and fractures. The connected porosities evaluated with the triple weight method range from 3.74 to 35.35% and show a good correlation (R2 = 0.8835) with the H2O+ values, revealing that porosity development is mainly due to the replacement of primary phases by clay minerals. In contrast, the crystallization of silica, carbonates and, to a lesser extent, iron oxides tends to clog connected pores, inducing a local decrease in connected porosity, as revealed in autoradiographs. The Darcian permeability ranges from 7.66∙10−20 to 5.36∙10−17 m2 and shows a moderate correlation with the connected porosity. The bulk electrical conductivity measured as a function of the conductivity of the saturating solution reveals the significant contribution of surface conduction arising from montmorillonite. At a pore fluid salinity of 2 wt% (the salinity of the Eaux Ferrées thermal spring), the bulk electrical conductivity shows a relatively good correlation with the H2O+ values (R2 = 0.8591) and an even better correlation with the MB values (R2 = 0.9579). The contribution of montmorillonite to the bulk electrical conductivity was estimated with the use of the isoconductivity point, showing an increase in the BM values and a strong correlation (R2 = 0.9806).

Adsorption characteristics of reactive blue 81 by powdered activated carbon: Role of the calcium content

Adsorption by powdered activated carbon (PAC) is an efficient method for dye removal from wastewater, but the factors that influence it remain unclear. In our work, seven PACs having high performance of removal reactive blue 81 (RB 81) were screened among fourteen PACs, and three PACs showed better removal efficiency after modified with calcium. The adsorption kinetics of selected six PACs except PAC14 and modified PACs with calcium well fitted to pseudo-second-order. The isotherms of the screened PACs excluding PAC12 and PAC13 were well described by Langmuir mode dominated by monolayer adsorption. The correlation analysis indicated that contents of carbon, oxygen and chlorine, as well as Iodine number and methylene blue adsorption value of seven PACs were irrelevant to the adsorption capacity. BET surface area and total pore volume moderately correlated with absorption capacity. Sulphur (S) and calcium (Ca) content of PACs were significantly linear with the absorption capacity of PACs. The S and Ca elements in PAC had a crucial role in RB 81 adsorption, which can be taken as the priority indicators during the selection and optimization of PAC for RB 81 adsorption. This study provides support for the evaluation and optimization of the compatibility between the adsorption efficiency of different pollutants and PAC.

Comparative study for fluidized bed pyrolysis of textile dyeing sludge and municipal sewage sludge

A comparative research was performed to evaluate the products yields and chars properties for pyrolysis of textile dyeing sludge (TDS) and municipal sewage sludge (MSS). The high fixed carbon (19.36 wt%) and low volatile (23.66 wt%) contents of TDS resulted in higher char yields and lower condensate yields. TDS char (TC) had a higher sulfur (S) retention efficiency than MSS char (MC) and CaO exhibited a great S retention effect in MC. More alkali and alkaline earth metals (e.g. Na, K, Mg and Ca) in MSS contributed to enhanced catalytic pyrolysis. In comparison to non-catalytic pyrolysis, chars from catalytic pyrolysis had lower iodine number and higher methylene blue (MB) adsorption value. MB adsorption values of MC (212.28–414.20 mg/g) were much higher than those of TC (84.32–156.07 mg/g). In contrast, heavy metals risk degrees of MC (4.20–7.56) were lower than those of TC (7.55–12.87), and heavy metals in TC and MC showed slight risks to environment.

Does the Methylene Blue Test Give Equally Satisfactory Results in All Studied Igneous Rocks Relative to the Identification of Swelling Clay Minerals?

The presence or the absence of swelling clay minerals in rocks, which are used in various construction applications, constitutes a determinant factor for their strength, and consequently, in their general behavior in various construction applications, as they have the ability to swell up to 400 times of their usual volume, causing failures to any application in which they participate. The aim of this study is to respond to the question of whether the empirical method of methylene blue yields equally safe and correct results in different types of igneous rocks and if not, which is the determining factor affecting the results. The answer to this complex question is feasible by investigating the microscopic structure and the mineralogy of the studied rocks, and particularly, using the content of specific phyllosilicate minerals which may be related or not with the methylene blue values. According to the results, the methylene blue test seems to work correctly for the intermediate (Group I) and mafic (Group II) examined rocks, but it seems to be wrong for the highly serpentinized ultramafic rocks (up to 70% of serpentine) (Group III).

Adsorption of congo red on mesoporous activated carbon prepared by CO2 physical activation

Abstract This research demonstrates the production of mesoporous activated carbon from sargassum fusiforme via physical activation with carbon dioxide. Central composite design was applied to conduct the experiments at different levels by altering three operating parameters. Activation temperature (766–934 °C), CO2 flow rate (0.8–2.8 L ⋅ min−1) and activation time (5–55 min) were the variables examined in this study. The effect of parameters on the specific surface area, total pore volume and burn-out rate of activated carbon was studied, and the influential parameters of methylene blue adsorption value were identified employing analysis of variance. The optimum conditions for maximum methylene blue adsorption value were: activation temperature = 900 °C, activation time = 29.05 min and CO2 flow rate = 1.8 L ⋅ min−1. The activated carbon produced under optimum conditions was characterized by BET, FTIR and SEM. The adsorption behavior on congo red was studied. The effect of parameters on the adsorbent dosage, temperature, PH and initial congo red concentration was investigated. The adsorption properties of the activated carbon were investigated by kinetics. The equilibrium removal rate and maximum adsorption capacity reaches up to 94.72%, 234 mg⋅g−1, respectively when initial congo red concentration is 200 mg⋅ L−1 under adsorbent dosage (0.8 g ⋅ L−1), temperature (30 °C), PH7.

Activated carbon preparation from pyrolysis char of sewage sludge and its adsorption performance for organic compounds in sewage

Although sludge pyrolysis has been extensively studied in sludge disposal, it is challenging to utilize sludge pyrolysis products. Here, we report a method for preparing sludge activated carbon (SAC) by activating sludge pyrolysis carbon by zinc chloride. The effect of ZnCl2 concentration, activation temperature and activation time on the activated carbon were investigated. The prepared activated carbons were characterized by thermogravimetric analysis, thermal kinetics analysis, Fourier transform infrared spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and N2 adsorption-desorption. The results show that when the ZnCl2 concentration was 8 mol/L with an activation time of 1 h at an activation temperature of 800 °C, the SAC iodine adsorption value and methylene blue adsorption value were 816.27 mg/g and 95.25 mg/g, respectively. The SAC exhibited a high BET surface area (up to 765.88 m2/g). The experimental results for simulated wastewater adsorption by SAC prepared under the above preparation conditions show that at an initial concentration of dimethyl phthalate (DMP) of 30 mg/L, addition amount of SAC of 20 mg, adsorption time of 30 min and temperature of 25 °C, the removal ratio of DMP can reach 87%. According to the data obtained, sludge pyrolysis char is a suitable precursor for activated carbon preparation. The obtained SAC could be used as a low-cost adsorbent with favorable surface properties.

Characterization of sugarcane bagasse and &lt;i&gt;Moringa Oleifera&lt;/i&gt; as potential adsorbent for the treatment of wastewater containing heavy metals

Activated carbon from sugarcane bagasse and Moringa oleifera were prepared and their textural properties were evaluated using Fourier transform infra-red (FT-IR) and scanning electron microscope (SEM). The chemical composition of sugarcane bagasse and Moringa oleifera was determine with the aid of X-ray fluorescence (XRF) while the surface area, micropore volume and total pore volume were estimated with the aid of structural characterization (SCAC) software using the iodine value and methylene blue number as the input parameters. The calculated iodine value and methylene blue value of sugarcane bagasse was 24.56mg/g and 2.27g/100g while for moringa oleifera, it was 29.48mg/g and 3.02g/100g. Based on these values, the surface area and total pore volume of sugarcane bagasse was estimated as 234m2/g and 0.14cm3/g, for Moringa oleifera it was 277.4m2/g and 0.21cm3/g. Results of the textural analysis revealed the presence of O-H stretching (which is the site for adsorption) in both the sugarcane bagasse and moringa oleifera. In addition, significant morphological differences were observed between the sugarcane bagasse and moringa oleifera with Moringa oleifera exhibiting better irregular and porous surface characteristics of different lamellae sizes.Keywords: Sugarcane bagasse, Moringa oleifera, Adsorption, Textural analysis

Performance evaluation of asphalt concrete mixes having copper industry waste as filler

Increase in demand of copper and copper allied products have led to unavoidable generation of billions of tons of copper tailings throughout the globe. This study investigated the possibility of utilizing copper tailings (CT) of Indian origin in place of conventional stone dust as filler in asphalt concrete mixes. Detailed physical, morphological and mineralogical characterization of both fillers was done through specific gravity, plasticity index, methylene blue value (MBV), particle size distribution, German filler values, Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), hydrophilic coefficient and pH value tests. Thereafter, asphalt concrete mixes containing both fillers were designed using Marshall mix design procedure and their optimum asphalt contents were determined. At their respective OAC’s, both mixes were compared on the basis of their stabilities, volumetric properties as well as their performance against various distresses (rutting, cracking, ravelling and moisture susceptibility) using relevant testing procedures. Copper tailing mixes delivered satisfactory Marshall and volumetric properties at relatively lower OAC than conventional mixes, which was attributed to the relatively lower porosity of copper tailings. Also, copper tailings mixes were found to have superior rutting and cracking resistances due to their lower VMA and fineness of copper tailings respectively. However, copper tailing mixes displayed relatively inferior (yet satisfactory) performance than conventional mixes in terms of moisture sensitivity, ravelling resistance, active and passive adhesion. This was due predominance of silica as well as absence of calcium based water insoluble minerals like dolomite in the composition of copper tailings.

Geotechnical Identification and Classification of Soils as Flexible Pavement Subgrade of the Section Fongo Tongo-Melong

The present study is inscribed within the framework of the geotechnical characterization of the soils of the Santchou plain, their classification for employment as pavement subgrade, various identification tests were carried out on the samples. The results obtained showed that with a wide range of different grain sizes, the studied soils showed low content in clay grains and dominance of either sand grains or silt grains, this can be explaining how most of these soil are poorly graded. According to the USDA textural classification, the grain size distribution of these soils makes them to be classified as Silty Loam types to Sandy Loam types. Despite of their organic matter content which is less than 10%, according to their respective methylene blue values, the soils studied along the section should be mainly loamy soil of medium plasticity to clayed soil, therefore showing a sensibility of its behavior to variation of water content. That last one is confirmed by the consistency parameters of these soils which show intermediate plasticity to highly plastic. Also, the bearing capacity proposed by these soils at their respective optimum dry densities is relatively small, although most of these experimental CBR values of the studied soils are more important than the ones prescribed by the AASHTO Classification system for A5, A6, and A7 types, and the French Highway Earthworks Manual Classifications system (GTR) for the corresponding A2 and A3 types.

Coupled effects of the content and methylene blue value (MBV) of microfines on the performance of manufactured sand concrete

This study investigated the coupled influences of the content and methylene blue value (MBV) of microfines on the comprehensive performance of manufactured sand concrete. The results show that microfines with a low MBV improve the workability of fresh concrete and the compactness of hardened concrete, thus improving certain properties of the concrete. In contrast, microfines with a high MBV are detrimental to frost resistance and shrinkage. Furthermore, the requirements regarding the allowable content of microfines can be relaxed depending on the associated MBV in order to make full use of microfines in manufactured sand concrete. Finally, this study calculates the coefficient of the coupled effects of the content and MBV of microfines on the performance of manufactured sand concrete based on the correlation theory and provides the basis for updating the content and MBV requirements for microfines in actual engineering. Sand can be replaced with microfines in traditional construction, transportation engineering and bridge engineering, thereby alleviating shortages of river sand.

Rheological and mechanical properties of bauxite residue as hot mix asphalt filler

Bauxite residue (red mud) is a highly alkaline solid waste generated in the process of production of aluminium metal from bauxite ore. More than 5.5 million tons of red mud is generated in India. The aluminium industries, worldwide and in India, have expressed strong need for dedicated research to explore large-scale utilization of red mud. Towards this end, the objective of this study is to investigate the use of red mud as a filler in hot mix asphalt (HMA). Stone dust, a traditionally used filler material, is used as the control filler. For a comprehensive evaluation approach, the present investigation is conducted at three levels: filler, mastic and mixture characterisation. Red mud and stone dust fillers are characterised using scanning electron microscopy (SEM), pH, Rigden voids, methylene blue value, particle size analysis, and specific surface measurement. Mastic rheology is studied using the dynamic shear rheometer by temperature sweep and multiple stress creep and recovery (MSCR) tests. Finally, dense-graded bituminous concrete (BC) mixes are designed by the Marshall method followed in India, at different filler contents of both filler types. Mixture performance is investigated in terms of indirect tensile strength and Cantabro abrasion loss. Results show that addition of both fillers improved the viscoelastic response of the base binder. Red mud mixes showed higher resistance to disintegration and higher tensile strength than the control mixes with stone dust filler. Based on the findings of this study, red mud showed good potential for use as a filler in dense graded bituminous mixes.

Effect of clay in alternative fine aggregates on performance of concrete

The worldwide utilization of alternative fine aggregates (AFA) in the construction sector is increasing exponentially these days due to extensive exploitation of natural sand. However, presence of excessive clay in AFA is considered harmful for fabrication of concrete and mortar. The existence of fine sediments like clay at the interstices of AFA highly influence the performances of concrete. Three types of AFA such as crushed rock sand (CRS), coal bottom ash (CBA) and recycle fine aggregates (RFA) are used in present study. Keeping in view, assessment of clay content in AFA is carried out by methylene blue test and their effects on performance of concrete. In this study, the volume fraction of AFA is varied by 30%, 50%, 75% and 100% respectively. Efforts were also made to develop standard correlation curve of methylene blue value of fine aggregates to corresponding clay content. The methylene blue value for all fine aggregates were well within 6 mg/g and correspondingly less than 5% clay content. Results indicated that MBV greater than or equal to 1.50 is not suitable for preparing concrete. It is also observed that properties and durability of these AFA concrete depend on the amounts of clay.

Recycle of cotton waste by hard templating with magnesium acetate as MgO precursor.

As one of the hard-templating methods, MgO-templating was employed to recycle cotton to produce activated carbon with magnesium acetate as MgO precursor. Results showed that cotton carbonized while magnesium acetate decomposed to nanoscale MgO particles based on thermogravimetric and X-ray diffraction analysis. Carbonized residuals of cotton were able to replicate the MgO morphology thus creating pores. The size of MgO varied with impregnation ratio, treatment temperature, and time. Overall, the optimum conditions were MgO/cotton impregnation ratio 0.25, temperature 800 °C, and treatment time 60 min. Cotton-based activated carbon thus produced manifested surface area and total pore volume of 1139 m2/g and 0.85 cm3/g respectively. Both micropores and mesopores were detected based on iodine, methylene blue adsorption values, and N2 adsorption-desorption studies.

Preparation of high specific surface area and high adsorptive activated carbon by KOH activation

Using mangosteen shell as raw material and KOH as the activator, the effects of different conditions on the yield of activated carbon, methylene blue, and iodine adsorption value were studied. Four factors were selected as an impregnation ratio, concentration of activator, activation temperature and activation time. The optimum technological parameters for preparing mangosteen shell activated carbon was determined by orthogonal experiment. The results were analyzed by pore size analysis and spectral analysis. Potassium hydroxide as an activator can easily produce macroporous activated carbon, which is a good adsorbent for garment printing and dyeing wastewater.

Surface properties, adherence, and photocatalytic activity of sol–gel dip-coated TiO2–ZnO films on glass plates

In this study, TiO 2 –ZnO nanostructured films prepared from different Ti/water mole ratios were deposited on glass plates by a sol–gel dip-coating method. The structural and surface properties, adherence, and photoactivity of synthesized TiO 2 –ZnO coatings in methylene blue degradation were investigated. Among the as-prepared TiO 2 –ZnO coatings from sols with different Ti/water mole ratios (1, 0.66, 0.5, and 0.4), the highest sol concentration (Ti/water mole ratio of 1) showed the highest methylene blue photodegradation of almost 80% after 400 min of UV irradiation. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Transmission electron microscopy (TEM), Energy-dispersive X-ray (EDX), and UV-vis diffuse reflectance spectra (DRS) confirmed that at high sol concentrations (Ti/water mole ratios of 1 and 0.66), a mixed phase of anatase and rutile is formed, whereas at a Ti/water mole ratio of 0.5, just pure rutile is formed. In detail, decreasing the sol concentration increases the cracks, degree of agglomeration, and the thickness of coatings. UV-vis DRS studies also confirm that decreasing the sol concentration in synthesized TiO 2 –ZnO films leads to a shift in the absorption region of the coating to the UV region. Moreover, decreasing the sol concentration declines the coating adherence onto glass plates. TEM images of the TiO 2 –ZnO coating synthesized from sol with a Ti/water mole ratio of 1 revealed the formation of ZnO nanorods around a spherical TiO 2 , which indicates the presence of strong interaction between TiO 2 and ZnO nanoparticles. The TiO 2 –ZnO coating synthesized from sol with a Ti/water mole ratio of 1 was then evaluated at different methylene blue concentrations, pH values, and number of coatings. After five consecutive runs, no significant decrease in the photodegradation efficiency was observed. Scanning electron microscopy (SEM) picture of used coating showed a smooth and stable layer without any detachment. Thermogravimetric analysis (TG) and sonication test confirmed thermal and mechanical stabilities of this coating as well.

Valorization of Phosphate Mine Waste Rocks as Materials for Road Construction

The road construction sector is a worldwide high consumer of natural aggregates. The use of unusual industrial by-products in road techniques can contribute to the conservation of non-renewable natural resources and the reduction of wastes produced by some industries. Phosphate waste rocks could be considered as potential alternative secondary raw materials in road construction. The use and valorization of these wastes is currently limited according to the Moroccan guide for road earthworks (GMTR). The guide has classified these materials as waste products, which consequently, cannot be used in road construction. However, phosphate waste rocks are sedimentary natural rocks which have not been subjected to any transformation other than mechanical fragmentation. The goal of this paper is to discuss key-properties of various phosphate mine waste rocks (PMWR) to be used as road materials. Samples were taken from different stockpiles in the phosphate mine site of Gantour in Morocco. The different waste rocks samples were characterized in terms of their physical, geotechnical, chemical, mineralogical and environmental properties using international testing norms. The obtained results showed that the studied PMWR presented satisfying characteristics; the specific (particle) density: ρs &gt; 26 kN/m3, Los Angeles abrasion: 45% &lt; LA &lt; 58%), methylene blue value MBV &lt; 1 g/100g, organic matter: OM &lt; 1% and plasticity index: PI &lt; 20%. All PMWR were confirmed as possessing the requested geotechnical properties to be used as materials for embankments. Moreover, leaching tests showed that none of them released any contaminants. In field application, these materials have been also successfully used in in situ experimental pilot testing. Therefore, the PMWR have to be classified in the category of natural aggregates that are similar to conventional materials.

Preparation and analysis of straw activated carbon synergetic catalyzed by ZnCl2-H3PO4 through hydrothermal carbonization combined with ultrasonic assisted immersion pyrolysis

In this paper, wheat straw (WS), corn straw (CS) and sorghum straw (SS) were used as raw materials. ZnCl2 and H3PO4 were used as catalysts. Hydrothermal carbonization combined with pyrolysis were used to co-activate with the ultrasonic auxiliary impregnation method in order to prepare straw activated carbon (SAC). Methylene blue adsorption value and iodine value were used as the main evaluation index to optimize the process conditions. The activation process was analyzed and the optimum preparation conditions were obtained. The results showed that it was feasible to combine hydrothermal carbonization with ultrasonic assisted immersion pyrolysis using ZnCl2 and H3PO4 as catalysts for preparing SAC. WS, CS and SS showed similar characteristics in the preparation of SAC. The best preparation conditions of hydrothermal temperature and the impregnation ratio of ZnCl2 were 200 °C and 2:1. The optimum pyrolysis condition was at a heating rate of 5 °C/min and an impregnation ratio of H3PO4 equal to 2:1 with 1 h of pyrolysis at 500 °C. The temperature and time of ultrasonic auxiliary conditions were 40 °C and 30 min. For WSHUPC, CSHUPC and SSHUPC, the MB adsorption values were 165, 166 and 164 mg/g and the iodine values reached 764, 725 and 701 mg/g. It was demonstrated the three kinds of straws were highly efficient precursor for the preparation of activated carbon used to remove dyes from wastewater. The preparation method in this study combines the advantages of physical and chemical activation.