Formulation and performance evaluation of a novel coconut oil–based metalworking fluid

Metalworking fluid (MWF) supplies a film of lubricant to abate friction, acts as a cooling media to rebate induced heat, and prevents metal pick-ups by flushing away the chips. Hence a liquid used as a cutting fluid reduces wear on the tool, reduces the energy consumption, and produces a better surface quality on the work piece. This paper describes the formulation of a novel water-soluble MWF and its performance evaluation during straight turning and end milling experiments carried out with AISI 304 stainless steel, mild steel, and cast iron as work piece materials. The MWF was prepared by mixing water with white coconut oil as the base oil and food-grade additives as surfactants. Viscosity, pH value, and biodegradability were measured and compared with a commercially available non-vegetable oil–based MWF. The surface roughness and tool surface temperature were measured throughout the machining experiments, and better performances were observed with the coconut oil–based MWF. Tool tip geometry and flank wear for straight turning machining operation were identified by observing scanning electron microscope (SEM) images.     

Anaerobic biodegradability and treatment of grey water in upflow anaerobic sludge blanket (UASB) reactor

Feasibility of grey water treatment in an upflow anaerobic sludge blanket (UASB) reactor operated at different hydraulic retention time (HRT) of 16, 10 and 6h and controlled temperature of 30 degrees C was investigated. Moreover, the maximum anaerobic biodegradability without inoculum addition and maximum removal of chemical oxygen demand (COD) fractions in grey water were determined in batch experiments. High values of maximum anaerobic biodegradability (76%) and maximum COD removal in the UASB reactor (84%) were achieved. The results showed that the colloidal COD had the highest maximum anaerobic biodegradability (86%) and the suspended and dissolved COD had similar maximum anaerobic biodegradability of 70%. Furthermore, the results of the UASB reactor demonstrated that a total COD removal of 52-64% was obtained at HRT between 6 and 16 h. The UASB reactor removed 22-30% and 15-21% of total nitrogen and total phosphorous in the grey water, respectively, mainly due to the removal of particulate nutrients. The characteristics of the sludge in the UASB reactor confirmed that the reactor had a stable performance. The minimum sludge residence time and the maximum specific methanogenic activity of the sludge ranged between 27 and 93 days and 0.18 and 0.28 kg COD/(kg VS d).     

A Review on the Applications of Ozonation for the Treatment of Real Agro-Industrial Wastewaters

Regarding agro-wastewaters, the strong loads in bio-refractory substances and seasonality reduce the efficiency of biological treatments and ozonation can play an important role, so that this article reviews its application for such streams. Indeed, biodegradability and toxicity removal was assessed for a wide range of agro-effluents such as olive mill, wineries and distilleries, pulp and paper, cork and cheese production. Solid catalysts reveal promising potential, even though literature is still scarce reporting their use to actual streams. Thus, forthcoming research must embrace catalytic ozonation and continuous pilot-scale reactors behavior on the depuration of real agro-wastewaters to ensure future industrial application.     

Synthesis and Surface Properties of Novel Quaternary Ammonium Gemini Surfactants with Polar Head Groups Containing 2-Hydroxypropyl Moieties

The purpose of this paper is to comprehend in-depth the effect of the surfactant structure on its and physicochemical properties such as surface/interfacial properties, foam stability, wettability, and biodegradability. To this end, quaternary ammonium Gemini surfactants, alkanediyl-α,ω-bis[(2-hydroxypropyl)dodecylammonium] dibromide (abbreviated as C_m-n-C_m[iso-Pr(OH)]₂ with m = 12, 14 and n = 2, 3, 4) were synthesized via substitution and quaternization reactions, and their chemical structures were characterized by Fourier transform infrared (FT-IR) and nuclear magnetic resonance (¹HNMR) spectroscopies. The results showed that with the decrease of the spacer length, the surface tension was reduced more strongly, and with the increase of the alkyl tail length, micelles were more easily formed. Besides, the highest surface activity of C₁₄-2-C₁₄[iso-Pr(OH)]₂ was observed by increasing NaCl concentration to 200 g L⁻¹. The temperature had a great influence on thermodynamic parameters of the adsorption and micellization. The interfacial tension between 0.26 g L⁻¹ C₁₄-2-C₁₄[iso-Pr(OH)]₂ solution and oil could reach 0.022 mN m⁻¹. An elongation of the spacer chain in C₁₄-n-C₁₄[iso-Pr(OH)]₂ was unfavorable to foam stability. Besides, the oil-wetted core, which was aged in 0.6 g L⁻¹ C₁₄-2-C₁₄[iso-Pr(OH)]₂ solution, exhibited more hydrophilicity. C_m-n-C_m[iso-Pr(OH)]₂ surfactants produced higher biodegradable rates in river water (≥ 90% after 28 days) than the biodegradable surfactant of international recommendation (71% after 28 days) at 30 °C.     

Green Engineered Polypropylene Biodegradable Fibers Through Blending with Recycled Poly(lactic) Acid Plastic Wastes

The modification of polypropylene (PP) fibers via blending with recycled poly(lactic) acid (r-PLA) flakes by a melt spinning method was investigated. Mechanical and morphological properties, biodegradability, differential scanning calorimetery (DSC) analysis, and dyeing behavior were carried out for physical and structural characterization of the fiber samples. The results showed that the PP/r-PLA blend fibers with the different blend ratios could be successfully melt spun along with suitable continuity. Acceptable tenacity and initial modulus and suitable biodegradability were obtained for the modified PP fibers. Dye uptake of the modified PP fiber samples was improved and the washing and light fastness of some them were excellent.     

A comparison of the structure, thermal properties, and biodegradability of polycaprolactone/chitosan and acrylic acid grafted polycaprolactone/chitosan

The effects of replacing PCL with acrylic acid grafted PCL (PCL-g-AA) on the structure and properties of a PCL/chitosan composite were investigated. The properties of both PCL-g-AA/chitosan and PCL/chitosan were examined and compared using FTIR, ¹H and ¹³C nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), and a biodegradation test. With PCL-g-AA in the composite, compatibility with chitosan and, consequently, the properties of the blend were both much improved due to the formation of ester and imide groups that conferred better dispersion and homogeneity of chitosan in the matrix. Moreover, PCL-g-AA/chitosan had a lower melt temperature and was, therefore, more easily processed than PCL/chitosan. Resistance to water was higher in the PCL-g-AA/chitosan blend, and consequently so was its resistance to biodegradation in soil and in an enzymatic environment. Nevertheless, weight loss of blends buried in soil or exposed to an enzymatic environment indicates that both blends were biodegradable, especially at high levels of chitosan content. Both blends suffered deterioration in tensile strength and elongation at break after exposure to soil or enzymatic environments.     

Controlled release of doxorubicin from amphiphilic depsipeptide–PDO–PEG-based copolymer nanosized microspheres

Novel biodegradable amphiphilic ABA triblock copolymers, i.e. poly(3(S)-methyl-morpholine-2,5-dione-co-p-dioxanone)-block-poly(ethylene glycol)-block-poly(3(S)-methyl-morpholine-2,5-dione-co-p-dioxanone) [P(MMD-co-PDO)-b-PEG-b-P(MMD-co-PDO)], were successfully prepared by ring-opening polymerization of 3(S)-methyl-morpholine-2,5-dione (MMD) and p-dioxanone (PDO) in the presence of poly(ethylene glycol) 6000 as an initiator. These triblock copolymers were characterized by ¹H NMR, ¹³C NMR, Fourier transform infrared, gel permeation chromatography and differential scanning calorimetry measurements. P(MMD-co-PDO)-b-PEG-b-P(MMD-co-PDO) could self-assemble into stable nanosized microspheres with critical micellar concentrations of 0.41–0.66 μg/mL. The microspheres showed high hydrolytic degradation. In addition, doxorubicin (DOX) was chosen as a model drug and successfully encapsulated into the microspheres by hydrogen-bond interaction and hydrophobic effect. The transmission electron microscopy and dynamic light scattering measurements revealed that these microspheres were ellipsoidal nanoparticles with diameters ranged from 50 to 100 nm. These copolymer microspheres exhibited high loading capacity (LC), encapsulation efficiency (EE) of DOX and sustained drug release behavior in phosphate buffered solution (PBS). Moreover, the release rate of DOX from those microspheres in pH 4.0 PBS was faster than that in pH 7.4 due to pH sensitivity of the polymer–drug systems and the degradation of the matrix polymers. These amphiphilic depsipeptide multiblock copolymers would be potential promising carriers for anti-tumour drug delivery.     

Effects Of Ozone On Kraft Process Pulp Mill Effluent

Effluent from a kraft process pulp mill was studied in a batch reactor for ozone doses between 50 and 200 mg O₃/L to identify the relative suitability of ozone application locations in the treatment process and see the improvements in biotreatability of wastewaters from a kraft process pulp mill. Laboratory acclimatized seed were used for BOD tests for ozonated and unozonated samples. The inhibitory effects were minimized by using optimum dilutions. The studies were divided into three major sections: characterization of mill effluent; ozone system calibration, and reactor design; and ozonation of mill effluent. Seed for Biochemical Oxygen Demand tests were acclimatized in batch units for primary, bleach and secondary effluents separately. The inhibitory effects which were noted with unacclimatized seed, were reduced by using laboratory acclimatized seed and optimum dilution which were determined during the characterization phase.

The batch reactor designed for the studies consisted of a cylindrical section for holding effluent, and a top spherical section for ozone/oxygen mixture. The reactor proved to be effective for controlling ozone dose. The variation in the applied ozone dose was less than 5 mg/L.

Bleach and primary effluents were treated with 50 and 100 mg/L ozone doses. Duplicate experiments were conducted for these effluents. Secondary effluent was studied for 50,100,150 and 200 mg/L ozone doses. Six replicate experiments were conducted for 50 and 100 mg/L ozone doses, whereas two experiments were carried out for 150 mg/L and one experiment for 200 mg/L ozone dose.

The results were analyzed using 't' test for paired experiments and ANOVA table for statistical confirmation. Residuals were plotted to check the assumptions of constant variance and normal distribution. The results indicated that 50 and 100 mg O₃/L effectively removed color from bleach effluent and primary effluent, but did not significantly change the BOD. Ozone was found to be effective for secondary effluent, as BOD₅ was increased by 65% for 50 and 100% for 100 mg O₃/L doses. The corresponding reduction in color was 62% and 82%, respectively. K_e and L_o values for the BOD equation were calculated by using the non-linear least square method for the BOD equation, giving joint confidence regions for the calculated parameters. It was concluded that ozone is most effective for the removal of color and the increase of BOD in secondary effluent.     

Characterizations of NOM included in NF and UF membrane permeates

The characteristic changes in the natural organic matter (NOM), from the feed to the permeate, due to nanofiltration (NF) and tight-ultrafiltration (UF), were investigated in terms of size (molecular weight), structure (hydrophobic and hydrophilic fractions), and functionality (charge density in terms of carboxylic acidity). These characteristic changes were expected to be associated with the reactivity of the disinfection by-products (DBP), fractions of biodegradable dissolved organic carbon (BDOC), and assimilable organic carbon (AOC) relative to the total organic carbon. The BDOC and AOC analyses demonstrated that the NOM included in the NF and tight-UF permeates were more biodegradable than those included in the feed waters, which were relatively hydrophilic and smaller, than those in the feed waters. The influence of the hydrodynamic operating condition in terms of the J₀/k ratio on the characteristics of the NOM included in the NF and tight-UF permeates was also demonstrated. In addition, the effects of the pH, ionic strength, and calcium ions on the specific UV absorbance (SUVA) values of the NOM in each of the feed and permeate waters, were demonstrated for a better understanding of the above characteristic changes, and to determine the applicability of the SUVA analysis for the characterization of the NOM.     

Ozonation of NSAID: A Biodegradability and Toxicity Study

This work deals with the biodegradability and toxicity of three non-steroidal anti-inflammatory drugs (NSAID) (diclofenac, ibuprofen and naproxen) treated by ozonation. The results show that the total removal of 200 mg L^?1 of diclofenac and 100 mg L^?1 of naproxen is possible using an ozone dose of 0.20 and 0.04 g L^?1, respectively. For 200 mg L^?1 of ibuprofen, 90% removal is achieved using an ozone dose of 2.3 g L^?1. The BOD₅/COD ratio, the Zahn-Wallens test and EC₅₀ toxicity test (Microtox) are chosen as biological and toxicity indicators of NSAID intermediates. The evolution of BOD₅/COD ratio during 1 hour of treatment is evaluated and the results show that ozonation improves the biodegradability for the three NSAID treated solution. The Zahn-Wellens test for diclofenac and ibuprofen solutions shows that biological mineralization, after 28 days, is higher for diclofenac than for ibuprofen solution. According to the Microtox test, the treatment with ozone removes the toxicity of the naproxen solution. Taking into account the results obtained with the biocompatibility tests it could be assumed that ozonation is an adequate treatment for removal NSAID in aquatic medium, and the ozonated effluents could be post-treated in a biological wastewater facility.