Use of digital image analysis combined with fractal theory to determine particle morphology and surface texture of quartz sands

The particle morphology and surface texture play a major role in influencing mechanical and hydraulic behaviors of sandy soils. This paper presents the use of digital image analysis combined with fractal theory as a tool to quantify the particle morphology and surface texture of two types of quartz sands widely used in the region of Vitória, Espírito Santo, southeast of Brazil. The two investigated sands are sampled from different locations. The purpose of this paper is to present a simple, straightforward,reliable and reproducible methodology that can identify representative sandy soil texture parameters.The test results of the soil samples of the two sands separated by sieving into six size fractions are presented and discussed. The main advantages of the adopted methodology are its simplicity, reliability of the results, and relatively low cost. The results show that sands from the coastal spit(BS) have a greater degree of roundness and a smoother surface texture than river sands(RS). The values obtained in the test are statistically analyzed, and again it is confirmed that the BS sand has a slightly greater degree of sphericity than that of the RS sand. Moreover, the RS sand with rough surface texture has larger specific surface area values than the similar BS sand, which agree with the obtained roughness fractal dimensions. The consistent experimental results demonstrate that image analysis combined with fractal theory is an accurate and efficient method to quantify the differences in particle morphology and surface texture of quartz sands.

Experimental investigation in the permeability of methane hydratebearing fine quartz sands

The permeability is one of the intrinsic parameters that determines the fluid flow in the porous media.The permeability in hydrate-bearing sediments affects the gas recovery and production of hydrate reservoirs significantly.The irregular permeability characteristics are challenging for fine-grained hydratebearing sediments.In this study,a series of experiments was conducted using an one-dimensional pressure vessel to investigate the hydrate formation characteristics and the permeability in hydratebearing fine quartz sands(volume weighted mean diameter was 36.695 mm).Hydrate saturations(0 e26%in volume)were controlled and calculated precisely based on the amount of injected water and gas,the system pressure and temperature.The results indicated that the hydrate nucleation induction period was completed during gas injection,and the average time of hydrate formation was within 500 min.The permeability of methane hydrate-bearing fine quartz sands was investigated by steady gas volume flow.For hydrate saturation lower than 13.94%,the hydrate mostly formed in grain-coating,the permeability reduction exponent calculated by Parallel Capillary,Kozeny Grain Coats and Simple Cubic Filling models were 2.00,2.10 and 1.74 respectively,and Simple Cubic Filling model was in accordance with the experimental data best.However,for hydrate saturation ranged from 13.94%to 25.91%,the permeability increased due to the flocculation structure formation of fine quartz sands and hydrate,which caused the increase of effective porosity.A new relationship among hydrate saturations,effective porosity,the ratio of permeability in the presence and the absence of hydrate was developed.This study developed the mathematical models for predicting the permeability with hydrate saturation in fine quartz sands,which could be valuable for understanding the characteristics of hydrate-bearing finegrained sediments.

S. E. M. analysis of quartz sand grains from selected Hong Kong and Chinese littoral environments

This pilot study attempts to demonstrate some underlying scanning electron microscopy themes of quartz grain surface textures. A variety of textural patterns and individual features are described for grains selected from various littoral environments. An attempt was made to differentiate samples on surface textures alone, but limitations of using this technique in sedimentological isolation were apparent. Statistical analysis of checklist data and photographic evidence revealed some of the more important feature combinations used in environmental diagnosis. The use of discriminant analysis provided quantitative sample separation.

A Study of the Adsorption of Molecular Deposition Filming Flooding Agent MD-1 on Quartz Sand

Molecular deposition filming flooding (MDFF) is a novel oil recovery technique based on the thermopositive monolayer electrostatic adsorption of the MDFF agent on different interfaces within reservoir systems. In this paper, the adsorption property of the MDFF agent, MD-1, on quartz sand has been studied through adsorption experiments at different pH and temperatures. Experimental data are also analyzed kinetically and thermodynamically. The results show that the adsorption of MD-1 on quartz sand takes place mainly because of electrostatic interactions, which corresponds to adsorption that increases with pH. Kinetic analyses show that at a higher pH the activation energy for adsorption gets lower and, therefore, the adsorption becomes quicker for MD-1 on quartz sand. Thermodynamic analyses show that pH plays an important role in the adsorption of MD-1 on quartz sand. At a higher pH, more negative surface charges result in the increase of electrostatic interactions between MD-1 and quartz sand. Therefore, the saturated adsorption amount increases and more adsorption heat will be released.

New Method for the Deep Dehydration and Desalination of Crude Oil

The present work focused on the environmentally friendly deep desalination of crude oil using ethylene glycol as the extraction solvent and quartz sand as the demulsifier.The effect of droplet size distribution in the emulsion on the dehydration results and desalination efficiency was investigated.Experimental results showed that the desalination efficiencies of Sarir and Basra crude oils were 93.3%and 90.0%,respectively.Furthermore,the desalination efficiency of Basra crude oil using ethylene glycol could be enhanced up to 96.7%by adding 30 g/L quartz sand with a particle size of 15μm.Finally,94%of the ethylene glycol and 86%of the quartz sand could be recovered from the emulsion.This process offers an alternative method to the deep desalination of crude oil.

Effects of Shear Fracture on In-depth Profile Modification of Weak Gels

Two sand packs were filled with fine glass beads and quartz sand respectively. The characteristics of crosslinked polymer flowing through the sand packs as well as the influence of shear fracture of porous media on the indepth profile modification of the weak gel generated from the crosslinked polymer were investigated. The results indicated that under the dynamic condition crosslinking reaction happened in both sand packs, and the weak gels in these two cases became small gel particles after water flooding. The differences were： the dynamic gelation time in the quartz sand pack was longer than that in the glass bead pack. Residual resistance factor （FRR） caused by the weak gel in the quartz sand pack was smaller than that in the glass bead pack. The weak gel became gel particles after being scoured by subsequent flood water. A weak gel with uniform apparent viscosity and sealing characteristics was generated in every part of the glass bead pack, which could not only move deeply into the sand pack but also seal the high capacity channels again when it reached the deep part. The weak gel performed in-depth profile modification in the glass bead pack, while in the quartz sand pack, the weak gel was concentrated with 100 cm from the entrance of the sand pack. When propelled by the subsequent flood water, the weak gel could move towards the deep part of the sand pack but then became tiny gel particles and could not effectively seal the high capacity channels there. The in-depth profile modification of the weak gel was very weak in the quartz sand pack. It was the shear fracture of porous media that mainly affected the properties and weakened the in-depth profile modification of the weak gel.

Removal of Phenanthrene from Contaminated Soil by Ozonation Process

In order to improve the ozonation efficiency for the remediation of PAHs contaminated soil,the performance experiments were carried out with quartz sand artificially contaminated with phenanthrene.The byproducts of phenanthrene were detected by GC-MS and the toxicity was evaluated by seed germination tests.The influence of the particle size and moisture content of quartz sand on the ozonation efficiency was investigated.In addition,two kinds of real soil was used to compare with the quartz sand.It was revealed that the phenanthrene removal rate reached 96%after 600 minutes by using the ozonation process.Three byproducts of phenanthrene,including 9,10-phenanthrenedione,(1,1’-biphenyl)-2,2’-dicarboxaldehyde,and(1,1’-biphenyl)-2,2’-dicarboxylic acid,were obtained.As proven by seed germination tests,the toxicity of the byproducts was lower than phenanthrene.The phenanthrene was removed more effectively by ozonation in the quartz sand with finer particle size.The ozonation efficiency was significantly improved by increasing the moisture content,which is assumed to be related to the alkalinity of quartz sand.

Allyl Glycidyl Ether-modified Animal Glue Binder for Improved Water Resistance and Bonding Strength in Sand Casting

This paper aims to develop a modified animal glue sand binder for foundry casting with improved water resistance and bonding strength.An efficient method is reported by using sodium hydroxide as the catalyst to improve the operability of animal glue binder and allyl glycidyl ether as the modifier to improve the water resistance and bonding strength.Sand specimens prepared using allyl glycidyl ether-modified animal glue binder were cured by compressed air at room temperature.The proposed method saves energy and is environmentally friendly and inexpensive.Compared with unmodified animal glue binder,standard dog bone sand specimens with allyl glycidyl ether-modified animal glue binder had higher tensile strength of 2.58 MPa,flowability of 1.95 g,better water resistance(a lower decrease in tensile strength at 25°C and relative humidity of 60%),and good collapsibility.This allyl glycidyl ether-modified animal glue binder is suitable for practical application in the foundry industry.

Comparison of quartz sand, anthracite, shale and biological ceramsite for adsorptive removal of phosphorus from aqueous solution

The choice of substrates with high phosphorus adsorption capacity is vital for sustainable phosphorus removal from waste water in constructed wetlands. In this study, four substrates were used： quartz sand, anthracite, shale and biological ceramsite. These substrate samples were characterized by X- ray diffractometry and scanning electron microscopy studies for their mineral components （chemical components） and surface characteristics. The dynamic experimental results revealed the following ranking order for total phosphorus （TP） removal efficiency： anthracite 〉 biological ceramsite 〉 shale 〉 quartz sand. The adsorptive removal capacities for TP using anthracite, biological ceramsite, shale and quartz sand were 85.87, 81.44, 59.65, and 55.98 mg/kg, respectively. Phosphorus desorption was also studied to analyze the substrates＇ adsorption efficiency in wastewater treatment as well as the substrates＇ ability to be reused for treatment. It was noted that the removal performance for the different forms of phosphorus was dependent on the nature of the substrate and the adsorption mechanism. A comparative analysis showed that the removal of particulate phosphorus was much easier using shale. Whereas anthracite had the highest soluble reactive phosphorus （SRP） adsorptive capacity, biological ceramsite had the highest dissolved organic phosphorus （DOP） removal capacity. Phosphorus removal by shale and biological ceramsite was mainly through chemical adsorption, precipitation or biological adsorption. On the other hand, phosphorus removal through physical adsorption （electrostatic attraction or ion exchange） was dominant in anthracite and quartz sand.

Removal of pharmaceutical in a biogenic/chemical manganese oxide system driven by manganese-oxidizing bacteria with humic acids as sole carbon source

Bioaugmented sand filtration has attracted considerable attention because it can effectively remove contaminants in drinking water without additional chemical reagent addition.In this study,a synthesized chemical manganese dioxide (MnO_(2)) -coated quartz sand(MnQS) and biogenic manganese oxide (BioMnOx) composite system was proposed to simultaneously remove typical pharmaceutical contaminants and Mn_(2)+.We demonstrated a manganese-oxidizing bacterium,Pseudomonas sp.QJX-1,could oxidize Mn_(2)+to generate BioMnOxusing humic acids (HA) as sole carbon source.The coaction of MnQS,QJX-1,and the generated BioMnOxin simultaneously removing caffeine and Mn_(2)+in the presence of HA was evaluated.We found a synergistic effect between them.MnQS and BioMnOxtogether significantly increased the caffeine removal efficiency from 32.8%(MnQS alone) and 21.5%(BioMnOxalone) to 61.2%.Meanwhile,Mn_(2)+leaked from MnQS was rapidly oxidized by QJX-1 to regenerate reactive BioMnOx,which was beneficial for continuous contaminant removal and system stability.Different degradation intermediates of caffeine oxidized by MnQS and BioMnOxwere detected by LC-QTOF-MS analysis,which implied that caffeine was oxidized by a different pathway.Overall,this work promotes the potential application of bioaugmented sand filtration in pharmaceutical removal in the presence of natural organic matter in drinking water.

Water softening by induced crystallization in fluidized bed

Fluidized bed and induced crystallization technology were combined to design a new type of induced crystallization fluidized bed reactor. The added particulate matter served as crystal nucleus to induce crystallization so that the insoluble material, which was in a saturated state, could precipitate on its surface. In this study, by filling the fluidized bed with quartz sand and by adjusting water pH, precipitation of calcium carbonate was induced on the surface of quartz sand, and the removal of water hardness was achieved. With a reactor influent flow of 60 L/hr, a fixed-bed height of 0.5 m, pH value of 9.5, quartz sand nuclear diameter of 0.2-0.4 mm, and a reflux ratio of 60%, the effluent concentration of calcium hardness was reduced to 60 mg/L and 86.6% removal efficiency was achieved. The resulting effluent reached the quality standard set for circulating cooling water. Majority of the material on the surface of quartz sand was calculated to be calcium carbonate based on energy spectrum analysis and moisture content was around 15.994%. With the low moisture content, dewatering treatment is no longer required and this results to cost savings on total water treatment process.