Dynamic Filtration Experiments Research Articles

Enhanced Antifouling Capability of In Situ-Grown Hydrophilic-Hydrophobic Nanodomains on Membrane Surface in the Ultralow Pressurized Ultrafiltration Process.

Although hydrophilic modification of the membrane surface is widely adopted, polymeric membranes still suffer from irreversible fouling caused by hydrophilic components in surface water. Here, an ultrathin hydrogel layer (40 nm) with hydrophilic-hydrophobic textures was in situ grown onto the polysulfone ultrafiltration membrane surface using an organic-radical-initiated interfacial polymerization technique. The interfacial polymerization of hydrophilic and hydrophobic monomers ensured the molecular-scale distribution of hydrophilic and hydrophobic nanodomains on the membrane surface. These nanodomains, with their molecular lengths, facilitated dynamic repulsion interactions between the uniformly textured surface and foulant components with different degrees of hydrophilicity. Chemical force characterization confirmed that the adhesion force between the hydrophilic-hydrophobic textured membrane surface and foulants (dodecane, bovine serum albumin, and humic acid) was greatly reduced. Dynamic filtration experiments showed that a hydrophilic-hydrophobic textured membrane always possessed the largest water flux and the best antifouling performance. Furthermore, the foulant coverage ratio on the membrane surface was first evaluated by measuring changes in surface streaming potentials, which demonstrated a 69% reduction in the amount of foulant adhering to the hydrophilic-hydrophobic textured membrane surface. Therefore, the construction of hydrophilic-hydrophobic nanodomains on the membrane surface provides a promising strategy for alleviating membrane fouling caused by both hydrophobic and hydrophilic components during ultralow pressurized ultrafiltration processes.

Molecular design of antifouling ultrafiltration membranes via copolymerization of bactericidal and hydrophilic polymers

Membrane fouling is still a significant obstacle to applying polyvinylidene fluoride (PVDF) ultrafiltration membranes. We developed bactericidal and hydrophilic comb copolymers to address this issue by introducing quaternary ammonium compounds (QAC) and sulfobetaine methacrylate (SBMA) onto PVDF powder. Utilizing atom transfer radical polymerization, we synthesized a series of polymer brushes by adjusting the QAC and SBMA functional monomers ratio. These polymer brushes were then employed to fabricate modified membranes featuring diverse alkyl chain lengths and hydrophilic layers. All modified membranes exhibited antibacterial and anti-adhesion properties. Increasing the SBMA monomer ratio resulted in reduced membrane pore size, a smoother membrane surface, and enhanced hydrophilicity. This balanced approach synergistically integrates “defensive” and “offensive” strategies, adjusting polymer proportions to confer dual functionality of hydrophilicity and bactericidal action in ultrafiltration membranes. Notably, the functionalized PVDF powder with copolymer chains exhibited a high inhibition efficiency of 100% against E. coli and 52.0% against E. faecalis, and the optimized membranes have an impressive performance of effectively preventing bacteria adhesion and inactivating attached bacteria. Dynamic filtration experiments further revealed the superior anti-biofouling capabilities of the modified membrane. Furthermore, the membrane containing 50% SBMA and 50% QAC exhibited a 69.5% improvement in anti-organic performance compared to those with only QAC. Our study presents a straightforward and efficient approach for designing antifouling PVDF membranes, showing great promise for wastewater treatment applications.

Quorum Quenching-Mediated Biofilm Mitigation on Functionalized Ultrafiltration Membranes via Atom Transfer Radical Polymerization

Quorum sensing (QS) critically affects biofilm formation during membrane filtration, which can be manipulated for membrane biofouling mitigation. This study demonstrates a quorum quenching strategy for combating membrane biofouling by functionalizing poly(vinylidene fluoride) (PVDF) membranes via atom transfer radical polymerization of a QS inhibitor, vanillin. Poly(vanillin) brushes are successfully grafted on the membrane surface, which is verified by extensive membrane characterization. The effective biofilm inhibition ability and mitigation mechanism of poly(vanillin) brushes are evaluated by analyzing the QS-related gene expression and acyl-homoserine lactone (AHL) signal molecule concentrations. We show that poly(vanillin) brushes can inhibit the bacterial QS system and decrease the AHL concentration to mitigate membrane biofouling. In dynamic filtration experiments, the vanillin-grafted PVDF membrane exhibits a 50% increase in stable flux compared to that of the pristine PVDF membrane. Our results provide an alternate strategy for mitigating membrane biofouling by regulating the bacterial QS system via inhibitor-functionalized membranes.

Viscose-Derived Activated Carbons Fibers as Highly Efficient Adsorbents for Dimethoate Removal from Water.

Extensive use of pesticides resulting in their accumulation in the environment presents a hazard for their non-target species, including humans. Hence, efficient remediation strategies are needed, and, in this sense, adsorption is seen as the most straightforward approach. We have studied activated carbon fibers (ACFs) derived from viscose fibers impregnated with diammonium hydrogen phosphate (DAHP). By changing the amount of DAHP in the impregnation step, the chemical composition and textural properties of ACFs are effectively tuned, affecting their performance for dimethoate removal from water. The prepared ACFs effectively reduced the toxicity of treated water samples, both deionized water solutions and spiked tap water samples, under batch conditions and in dynamic filtration experiments. Using the results of physicochemical characterization and dimethoate adsorption measurements, multiple linear regression models were made to reliably predict performance towards dimethoate removal from water. These models can be used to quickly screen among larger sets of possible adsorbents and guide the development of novel, highly efficient adsorbents for dimethoate removal from water.

Zwitterionic hydrogel modified reduced graphene oxide/ZnO nanocomposite blended membrane with high antifouling and antibiofouling performances

Membrane fouling and biofouling are major challenges in the application of membrane technology for wastewater treatment. The synthesis of antifouling and antibiofouling dual functionality membranes is a promising approach to tackling these problems. In this work, we fabricated a high-efficiency dual functionality polyethersulfone (PES) ultrafiltration membrane by blending an antibacterial reduced graphene oxide-ZnO nanocomposite into a PES matrix (rGO/ZnO–PES) followed by surface grafting of a low-fouling polyampholyte hydrogel (rGO/ZnO–z–PES). The antibacterial activity of the blended membrane was optimized by changing the nanocomposite fraction in the PES dope solution. Surface characterizations (SEM-EDS, XPS, ATR-FTIR, contact angle, and Zeta potential) confirmed the successful grafting of the zwitterionic hydrogel on the rGO/ZnO–PES membrane surface. Contact killing assays revealed that the polyampholyte hydrogel grafting did not affect the high antibacterial activity of the rGO/ZnO–PES membrane. Dynamic filtration experiments demonstrated the very high antifouling and antibiofouling of the rGO/ZnO–z–PES membrane, and significantly higher than those of the rGO/ZnO-PES and pristine PES membranes. The measured concentration of zinc ions in the permeate was low. Overall, our results demonstrate that the rGO/ZnO–z–PES membrane has excellent antifouling and antibiofouling performance and is stable and safe, and therefore very promising for wastewater treatment.

Electrostatic assembly construction of polysaccharide functionalized hybrid membrane for enhanced antimony removal

There is a growing demand for heavy metal removal by membrane technology in real applications. However, few studies were reported concerning antimony (Sb) removal by membrane technology. Herein, a novel thin film nanocomposite (TFN) membrane comprising an alginate (SA) selective layer and a polyether sulfone (PSF) support membrane incorporating chitosan functionalized iron nanocomposite has been firstly developed for Sb removal via electrostatic self-assembly. The support matrix membrane contained iron nanocomposite (denoted as CIM) retained high water flux and porosity, and it reached a maximum removal capacity of 16.5 and 13.6 mg/g for Sb(III) and Sb(V) with nanofiller loading rate of 20% during static experiments, respectively. The coated SA top layer endowed the hybrid membrane (denoted as SA-CIM) to have a lower membrane flux, and have stronger retention abilities for Sb species than that by CIM during dynamic filtration experiments. The SA-CIM membranes also possess tolerable reversibility towards Sb removal. Benefiting from the negatively-charged dense selective layer and high adsorption capacity of the iron nanocomposites, the SA-CIM membranes demonstrated an enhanced removal capacity for Sb species via steric hindrance effect, electrostatic repulsion and adsorption. Our study offers a simple method to remove Sb by a novel polysaccharide functionalized hybrid membrane.

Properties and performance of Ag(I) ion imprinted PVDF-PVA/GO composite membrane: Enhanced permeability, rejection and anti-microbial ability

A novel composite membrane with enhanced permeability, rejection and anti-microbial ability was fabricated through chemical modification of PVDF membrane with silver (Ag) ion imprinted poly(vinyl alcohol)/graphene oxide (PVA/GO) thin layer. The physico-chemical properties of the membranes were investigated by a series of analysis techniques. The membrane filtration performance, i.e., pure water flux and rejection efficiency of NaCl, MgSO4 and bovine serum albumin (BSA), was found to be highly affected by the modification processes. Although rejection performance of the H-PVDF-PVA/GO-m-Ag membrane was observed to be slightly decreased compared to that of the H-PVDF-PVA/GO membrane, the uniform imprinting of Ag ions on the membrane surface can endow the membrane with excellent anti-microbial ability. According to results from both batch and dynamic filtration experiments, the H-PVDF-PVA/GO-m-Ag membrane can effectively inactivate 58% and 100% of Pseudomonas aeruginosa cells after incubation for 1 and 4 ​h, respectively and reduce approximately 94% of surface adhesion density. The prepared membrane with the excellent anti-biofouling ability exhibited a promising application potential in water treatment processes.

A novel membrane biofouling mitigation strategy of D-amino acid supported by polydopamine and halloysite nanotube

D-amino acid (DAA) an environmentally friendly biofilm inhibitor, has low efficiency for membrane biofouling control due to its instability. To address this challenge, a novel nanocomposite was prepared with DAA adhering to polydopamine (PDA)-coated halloysite nanotube (HNTs) through the interactions of H-bonding and π-π stacking between PDA and DAA. Membrane modified with such nanocomposite was fabricated via blending phase inversion, and the nanocomposite was uniformly distributed in the modified membrane matrix. In comparison with the pristine membrane, the addition of nanocomposites resulted in robust mechanical property for modified membrane with the ultimate stress and strain increased by 23.97% and 35.62%, respectively. Moreover, an excellent tradeoff between water flux (2.5 folds of pristine membrane) and selectivity was achieved, probably due to the improved membrane hydrophilicity. Meanwhile, bovine serum protein (BSA) static adsorption as well as dynamic filtration experiments exhibited excellent antifouling ability of the modified membrane. Most importantly, a superior anti-biofouling stability over a 10-day period was obtained for the membrane modified with nanocomposite, indicating that the activity of DAA to mitigate biofouling was effectively maintained. This study developed a novel and promising strategy for membrane biofouling mitigation.

Functionalization of ultrafiltration membrane with polyampholyte hydrogel and graphene oxide to achieve dual antifouling and antibacterial properties

Membrane modification using zwitterion polymers is an excellent strategy to reduce organic fouling and initial bacterial deposition, and functionalization of the membrane surface with antibacterial material can reduce biofilm formation. In this study, we combined these two approaches to develop an ultrafiltration polyethersulfone (PES) membrane with dual antifouling and antibacterial properties. At the beginning, a zwitterion polyampholyte hydrogel was UV grafted onto PES membrane surface (p-PES membrane). Then, the hydrogel was loaded with graphene oxide (GO) nanosheets using vacuum filtration strategy (GO-p-PES membrane). Raman spectroscopy and scanning electron microscopy (SEM) confirmed the successful incorporation of the GO nanosheets into the zwitterion hydrogel, and contact angle measurements indicated that the membrane hydrophilicity was enhanced. Static adsorption and dynamic filtration experiments demonstrated that the p-PES and GO-p-PES membranes exhibited similar organic fouling propensity. Moreover, the loading of GO induced antibacterial property for the membrane as evidenced by contact killing and antibiofouling filtration experiments. Leaching of GO was very low, with over 98% of the GO remaining on the membrane surface after 7 days. Our findings highlight the potential of this GO-functionalized polyampholyte hydrogel for long-term wastewater treatment.

Internal pore decoration with polydopamine nanoparticle on polymeric ultrafiltration membrane for enhanced heavy metal removal

Novel ultrafiltration-adsorption membranes (UFAMs) were designed via decorating the walls of membrane internal pores with polydopamine (PDA) nanoparticles for heavy metals removal. Specially, self-polymerized dopamine solution was penetrated through the polyethersulfone (PES) UF membrane from reverse direction (i.e., from bottom to top) by circulatory filtration, leading to the formation of a PDA nanoparticle coating around the walls of finger-like pores (labeled as PES/PDA-R). The conventional PDA-decorated membrane (labeled as PES/PDA-F) prepared with forward filtration was used for comparison. The results indicated that the introduction of PDA nanoparticles on the walls of internal pores endowed the PES/PDA-R membrane with enhanced UF performance and remarkable adsorption capacity for heavy metals. PES/PDA-R membrane exhibited ascendant bovine serum albumin (BSA) rejection (92.9%) and maintainable pure water flux (166L/m2h). The static adsorption capacities for Pb2+, Cd2+ and Cu2+ on PES/PDA-R membranes were 20.23mgPb/g, 17.01mgCd/g and 10.42mgCu/g, respectively, which are 1.69, 2.25 and 1.91times higher than that of the PES/PDA-F membranes. Importantly, dynamic filtration experiments revealed 4.13times adsorption capacity for Pb2+ was achieved on PES/PDA-R membrane over PES/PDA-F membrane. The significant enhancement of dynamic adsorption capacity on PES/PDA-R membrane is derived from the three dimensional distribution of PDA nanoparticles on the cross section of PES membrane which provide the more active sites and increase the contact time between PDA and metal ions. This novel approach paves a way to design specific composite membranes for a cost-effective water treatment.

Grafting of oligodeoxynucleotide hairpin onto membrane surface to improve its anti-fouling performance

Polyacrylonitrile (PAN) membrane has been widely used in traditional ultrafiltration processes. However, the nonspecific adsorption of proteins on PAN membrane reduces the flux and increases the operation cost by requiring extra process of cleaning. Generally, hydrophilic and electrically neutral reagents such as polyzwitterionic materials were used to improve its anti-fouling performance. In the present study, a negatively charged oligodeoxynucleotide with a hairpin structure was first grafted onto PAN membrane to improve its anti-fouling capacity. The oligodeoxynucleotide modified (OPAN) membranes were characterized in terms of chemical composition, morphology, and surface properties indicating that the oligodeoxynucleotide could successfully be bonded onto the PAN membrane. The anti-protein-fouling properties of the membrane were tested using static protein adsorption and dynamic-filtration experiments. The experimental results indicate that the flux ecovery rate of the OPAN membrane was much higher than that of the pure PAN membrane. The improved anti-fouling performance of the membrane is suggested to be attributed to the steric hindrance and electrostatic repulsion between the oligodeoxynucleotides and the proteins.

Polyacrylonitrile-based zwitterionic ultrafiltration membrane with improved anti-protein-fouling capacity

The adhesion of proteins to the surface and pores of ultrafiltration membrane is one of the most important causes of membrane fouling, consequently lead to deterioration of membrane performance. In the present study, a polyacrylonitrile (PAN)-based zwitterionic ultrafiltration membrane was developed to improve its anti-protein-fouling capacity. 3-Dimethylaminopropylamine was first grafted onto the hydrolyzed PAN membrane by activation. Subsequently, carboxylic zwitterions were produced on the membrane surface by quaternization with 3-bromopropionic acid. The zwitterionic membranes were rigorously characterized in terms of chemical composition, morphology, and surface properties indicating that the zwitterion could successfully be bonded onto the PAN membrane without having significant effects on the membrane morphology. The anti-protein-fouling properties of the membrane were tested using static protein adsorption and dynamic-filtration experiments. The experimental results show that, although the hydrophilicity of the zwitterionic membrane decreased, the flux recovery rate of the zwitterion-grafted membrane was much higher than that of the hydrolyzed PAN membrane. Therefore, the formation of zwitterionic hydration layer may effectively prevent the adsorption interaction between protein and membrane surface, which is beneficial for the improvement of the anti-protein-fouling capacity.

Improving Anti-Protein-Fouling Property of Polyacrylonitrile Ultrafiltration Membrane by Grafting Sulfobetaine Zwitterions

Zwitterions show great superiority in the field of polymer membrane surface functionalization, as the synthesis process is simple, the adaptability of functional groups is strong, and zwitterions with strong hydration capacity in aqueous solutions can inhibit protein adsorption. In this study, a polyacrylonitrile ultrafiltration membrane was modified to improve anti-protein-fouling capacity by grafting short-chain sulfonic type zwitterions. 3-Dimethylaminopropylamine was first grafted onto hydrolyzed polyacrylonitrile (PAN) membrane by the activation of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC). Subsequently, sulfobetaine zwitterions emerged on the membrane surface by quaternization of 1,3-propane sultone. The sulfobetaine zwitterionic membranes were analyzed for surface chemical composition, hydrophilic properties, and surface and cross-sectional structure of the membrane, by a combination of Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, contact angle measurement, and scanning electron microscopy. Static protein adsorption and dynamic filtration experiments were undertaken to show that the modified membrane had excellent resistance to protein adsorption. It was found that the molecular weight cutoff of the substrate membrane had great influence on the flux recovery rate of the modified membrane.

Electrospun fibrous mats as a skeleton for fabricating hierarchically structured materials as sorbents for Cu2+

Based on the combination of the electrospinning and evaporation-induced self-assembly mesopore-forming technique, a facile strategy is developed to fabricate self-standing thiol-functionalized membranes with hierarchical structures (Macro-Mesopores and binding sites). This membrane is prepared using electrospun polystyrene (PS) fibers as the skeleton and non-ionic surfactant F127 as the structure-directing agent with co-condensation of tetraethyl orthosilicate (TEOS) and 3-mercaptopropyltrimethoxysilane (MPTMS). The prepared membranes were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope (SEM), nitrogen sorption, mercury intrusion porosimetry, and Fourier transform infrared (FT-IR) spectra. The macropore constructed by the electrospun PS membrane ranged from 1 to 10 μm, while the highly ordered mesopore formed by F127 was around 5 nm and heavy metals binding cites of thiol groups were also presented, respectively. Using Cu2+ ions as the model bivalent cation, an excellent removal capacity of the prepared membrane was confirmed by the static sorption and dynamic filtration experiments with a high flux up to 1.30 × 104 L h−1 m−2bar−1. We find that regeneration of the membranes and the metal ion recovery can be facially realized by the treatment using acid solution. These results demonstrate that the developed strategy has significant potential for the design and fabrication of high-performance membranes with hierarchical structures and could find impactful application in the field of industrial catalysis, separation, and environmental pollution control and resources reuse.

Heavy metal-contaminated groundwater treatment by a novel nanofiber membrane

The morphology, interspace and surface properties of a novel nanofiber membrane are characterized by scanning electron microscopy (SEM), pore percent and contact angle. The membrane, named M-1, is prepared from chloridized polyvinyl chloride by high-voltage electrospinning process. The removals of divalent metal cations including Cu 2+, Pb 2+ and Cd 2+ from the simulated groundwater by M-1 have been investigated. To obtain the best heavy metal removal, several experimental methods using M-1 have been presented, including static adsorption, direct filtration, soil-addition filtration, diatomite-addition filtration and micellar enhanced filtration (MEF). Specially, MEF experiments are performed as a function of SDBS concentration and applied membrane layers. From static adsorption experiments, maximum uptakes of Cu 2+, Cd 2+, Pb 2+ and their adsorption equilibrium time have been obtained respectively in the simulated groundwater. Dynamic filtration experiments indicate that the best experimental method for M-1 to remove heavy metal cations is MEF whose optimal experimental conditions are 10-layer filtration and sodium dodecyl benzene sulfonate (SDBS) concentration of 5mmol/L. The experimental results show that the rejections of copper in the simulated groundwater by MEF using M-1 can reach more than 73%; the rejections of lead more than 82%; and the rejections of cadmium more than 91%. It is indicated that MEF method using M-1 can be used for the treatment of the groundwater containing Cu 2+, Pb 2+ and Cd 2+ with high efficiency.

Formation Damage vs. Solid Particles Deposition Profile During Laboratory-Simulated Produced-Water Reinjection

SummaryThe importance of produced water reinjection (PWRI) is unquestionable. It is in many cases the cheapest and most environmentally friendly solution for wastewater disposal. It is also a feasible method for enhanced oil recovery (EOR) as a waterflooding mechanism.PWRI, however, suffers from a major limitation, which is the current inability in accurately predicting the lifespan and performance of its injection wells. This is because of the multitude of parameters that affect it. Current models1,2 that incorporate the thermal effects3 of PWRI leading to fracture growth exist. However, the leakoff pattern of this injection differs from that of clean water (seawater) injection because of the damage caused by the produced water to the formation, especially to the fracture faces. Thus, static filtration experiments with refined post-mortem analysis have been conducted to obtain quantitative deposition profiles along the core. This allows for the testing and verification of existing models.4–8The post-mortem analysis introduced in this paper will be used for future dynamic filtration experiments as well as experiments specifically devised to simulate the fracture tip area. A unified model that will accurately reproduce the permeability decline and deposition profile for all three sets of experiments will follow, thus advancing the predictability of injectivity decline associated with PWRI.The purpose of this paper is to provide a detailed description of the post-mortem analysis, while rigorous testing of the existing heuristic models (for instance, Wennberg and Sharma6 and Bedrikovedski et al.7) will be published in the near future.9

Performance Evaluation and Formation Damage Potential of New Water-Based Drilling Formulas

Summary Formation damage risks are well documented for standard mud formulations but they are poorly analyzed for new types of non-polluting muds. This paper describes extensive laboratory work aimed at evaluating the behavior of these new types of mud formulations. First, static and dynamic filtration experiments were conducted on paper filters and rock slices. Examination of mud cakes by means of cryo-SEM has permitted correlation of filtration behavior with the structural characteristics of both external and internal mud cakes. Then, the simulation of the full process of mud invasion in oil-bearing reservoirs was achieved by performing static and dynamic filtration experiments in a specially designed core-holder cell containing 40 cm long sandstone core samples. Cumulative filtrate losses and pressure drops across six sections of the core, while circulating the mud and back flushing the oil, were continuously monitored to evaluate the permeability damage. Damage arising from overbalanced conditions has been evaluated in terms of cake permeability, fluid loss characterization and reduction in oil permeability after mud exposure. For the three mud compositions tested here, the filtration process in high permeability sandstones is mainly controlled by external mud cakes. Damage is severe but an additional damage due to the trapped aqueous filtrate phase can strongly affect the oil relative permeabilities. This approach has given a complete behavior understanding of new water based drilling fluid formulations including evaluation of their performances, limits of use at high temperature and assessment of risks for different operational conditions.

Impact of catalytic ozonation on the removal of a chelating agent and surfactants in aqueous solution

The present work consisted in the study of the oxidation yield induced by catalysts during ozonation of sodium gluconate, toluene sulfonic acid and Triton X100 in dilute aqueous solution (TOC ≈ 8 mg C/L). Two operating conditions have been used to demonstrate the enhancement brought about by catalytic ozonation: continuous filtration experiments and batch tests. Dynamic filtration experiments have been performed on catalysts previously saturated to simulate the behavior of the catalyst over a long period of use. Batch experiments which allowed us to distinguish the part due to adsorption, ozonation and catalytic effect were carried out on three catalysts with intent to test their efficiency.

On the Effect of Mobile Oil Saturation On Fracturing Fluid Leakoff Characteristics In High-permeability Reservoirs

Abstract This paper presents the results of experiments and simulations conducted to investigate the effect of mobile oil saturation on the fracturing fluid leakoff characteristics under dynamic conditions in high permeability reservoir rocks. The fluid leakoff behaviour is examined for samples of varying permeability. In addition, the effectiveness of fluid loss additive in the presence of mobile oil saturation is investigated. A conceptually consistent model to predict the leakoff rate in the presence of mobile oil saturation at the fracture face has been developed. The model is validated using data obtained from dynamic leakoff tests. The results demonstrate that the presence of mobile oil saturation at the fracture face causes the leakoff characteristics to be very different from the tests for which the fracture face is completely saturated with brine. The leakoff characteristics are also affected by the fracture face permeability. Introduction In recent years, increasingly higher permeability formations are being hydraulically fractured (frac-pack) to overcome formation damage and/or prevent sand production problems(1–3). It is usually assumed that during initial stages of frac-pack treatments, a large amount of spurt loss occurs, which contributes to low fluid efficiency and high pumping cost(4). Spurt loss should be controlled in order to reduce the pumping cost and improve the economics of frac-pack treatments. Fluid loss additives are expected to reduce spurt loss by blocking the pore throats of the reservoir rock in the vicinity of the fracture face. In the design of fracturing fluid, the presence of oil in the reservoir which can significantly affect spurt loss and the performance of fluid loss additives, is usually ignored. Very few studies have been published on dynamic fracturing fluid leakoff behaviour in high permeability formation core samples. Further, the core samples in the available studies(4–6) were completely saturated with brine, in contrast to the in situ reservoir samples that have significant oil saturation. The effect of mobile oil saturation in the reservoir on the leakoff characteristics and quality of filter cake has rarely been addressed in the literature. The objective of the present study is to investigate the leakoff behaviour of fracturing fluids in the presence of mobile oil saturation. This objective is accomplished by conducting dynamic filtration experiments on core samples containing mobile oil saturation. A rigorous interpretation of these experiments involving cake build-up and multiphase flow is accomplished by using a mathematical model that incorporates the current understanding of the flow of non-Newtonian fluids, filtration and cake build-up, and multiphase flow in porous media(7). Experimental Setup and Procedures An experimental setup was designed and assembled for studying dynamic leakoff of fracturing fluids in the presence of mobile oil saturation. This setup is similar to the one used in an earlier study(7) except that the core holder is mounted horizontally. Experimental Setup Figure 1 illustrates the schematic of the experimental setup. A detailed description of the setup is presented by Gadiyar et al.(7) The major components of the flow system are: dynamic leakoff core holder, fluid displacement and pumping unit, pressure transducer manifold, and data acquisition system.