Concentrated Acid Treatment Research Articles

An investigation of methods to enhance adhesion of conductive layer and dielectric substrate for additive manufacturing of electronics

Additive manufacturing of conductive layers on a dielectric substrate has garnered significant interest due to its promise to produce printed electronics efficiently and its capability to print on curved substrates. A considerable challenge encountered is the conductive layer’s potential peeling due to inadequate adhesion with the dielectric substrate, which compromises the durability and functionality of the electronics. This study strives to facilitate the binding force through dielectric substrate surface modification using concentrated sulfuric acid and ultraviolet (UV) laser treatment. First, polyetheretherketone (PEEK) and nanoparticle silver ink were employed as the studied material. Second, the surface treatment of PEEK substrates was conducted across six levels of sulfuric acid exposure time and eight levels of UV laser scanning velocity. Then, responses such as surface morphology, roughness, elemental composition, chemical bonding characteristics, water contact angle, and surface free energy (SFE) were assessed to understand the effects of these treatments. Finally, the nanoparticle silver ink layer was deposited on the PEEK surface, and the adhesion force measured using a pull-off adhesion tester. Results unveiled a binding force of 0.37 MPa on unmodified surface, which escalated to 1.99 MPa with sulfuric acid treatment and 2.21 MPa with UV laser treatment. Additionally, cross-approach treatment investigations revealed that application sequence significantly impacts results, increasing binding force to 2.77 MPa. The analysis further delves into the influence mechanism of the surface modification on the binding force, elucidating that UV laser and sulfuric acid surface treatment methods hold substantial promise for enhancing the binding force between heterogeneous materials in the additive manufacturing of electronics.

Effects of Carbon Black Surface Modification on the Morphology and Properties in Blends with Natural Rubber Studied with High‐Resolution X‐Ray Computed Tomography

AbstractTo elucidate the specific mechanical impact of carbon black (CB) filler–rubber interactions on reinforcement, CB particles are subjected to graphitization at 1300 °C and oxidation through concentrated nitric acid treatment to modulate their surface activity. Alongside untreated CB particles, the influence of surface activity and the oxygen distribution are investigated to assess their role in shaping CB aggregate structures using X‐ray absorption spectrum (XAS) and X‐ray computed tomography (CT) with spatial resolution of 30 nm. Meanwhile, virgin and modified CBs are blended in natural rubber with varying amounts (10, 30, 50 phr) and the aggregates distributions in rubber are investigated by nano‐CT. Combined with the mechanical properties of rubber composites and parameters of filler networks, the mechanical contributions arising from filler–rubber interactions are quantified. The findings underscore the robust interactions between oxidized CB and rubber matrix, exhibiting a mechanical property enhancement ratio of ≈59.2% at low strains in comparison to normal CB filler. The results indicate the synergies encompass of filler network, rubber chains, and filler–rubber interactions all play important roles for reinforcement, which aligns with the broader understanding of filler–rubber interactions and CB reinforcement mechanisms.

N-doped EG@MOFs derived porous carbon composite phase change materials for thermal optimization of Li-ion batteries at low temperature

Electric vehicles often encounter the challenge of battery capacity reduction in cold environments. Existing thermal conductive patches and partial short-circuiting for electrical heating can address the above issues. In this paper, a method to increase battery capacity was proposed by phase change material (PCM) assisted heating. Specifically, a nitrogen-doped hierarchical porous carbon (NPC) was synthesized through a combination of “low-temperature calcination + concentrated nitric acid treatment” to treat the chrysanthemum-shaped MOF-199@EG, and impregnated with stearic acid (SA) to form a stable composite PCM. With its well-developed pore structure and N-adsorbed active sites, the NPC prevents the leakage of molten SA, maintains stability effect and significantly improves the thermal properties of SA composites. The SA/NPC has a loading rate of 80.15 wt%, closely approaching the theoretical values of latent heat (137.89 J·g-1). It also demonstrates enhanced thermal conductivity (1.873 W·m-1·K-1) and thermal diffusivity (1.024 mm2·s-1). Thermal conductivity and thermal diffusivity of SA/NPC are 8.56 times and 14.06 times higher, respectively, than those of SA. Furthermore, when the lithium-ion battery is discharged 2C at −20 °C, the utilization of SA/NPC as an insulation material can increase the discharge energy by 7.89 %. Consequently, this novel composite PCM holds significant promise for the thermal optimization of batteries at low temperature.

The transformations of cellulose after concentrated sulfuric acid treatment and its impact on the enzymatic saccharification

BackgroundThe dense structure of cellulose lowers its reactivity and hinders its applications. Concentrated sulfuric acid is an ideal solvent to dissolve cellulose and thus has been used widely to treat cellulose. However, the changes of cellulose after reaction with concentrated sulfuric acid at near-limit S/L ratio and its effect on enzymatic saccharification still need further investigation.ResultsIn this study, the interactions between cellulose (Avicel) and 72% sulfuric acid at very low acid loading conditions of 1:2 to 1:3 (S/L ratio) were studied for the enhanced production of glucose. The Avicel gradually transformed from cellulose I structure to cellulose II structure during the sulfuric acid treatment. Other physicochemical characteristics of Avicel also changed dramatically, such as the degree of polymerization, particle size, crystallinity index, and surface morphology. After acid treatment, both the yield and productivity of glucose from cellulose increased significantly under a very low enzyme loading of 5 FPU/g-cellulose. The glucose yields for raw cellulose and acid-treated (30 min) were 57% and 85%, respectively.ConclusionLow loadings of concentrated sulfuric acid were proven to be effective to break the recalcitrance of cellulose for enzymatic saccharification. A positive correlation between cellulose CrI and glucose yield was found for concentrated sulfuric acid-treated cellulose, which was opposite to previous reports. Cellulose II content was found to be an important factor that affects the conversion of cellulose to glucose.

Preparation of CdS/g-C3N4 heterojunction photocatalyst with high activity sites by acid treatment

The key to achieve efficient degradation of organic pollutants lies in improving the separation efficiency of photogenerated electron-hole pairs in photocatalysts. Here, the hydrogen bonds between g-C3N4 layers were broken by concentrated acid etching and exfoliation to obtain a more dispersed and lighter g-C3N4 nanosheet structure, and then the CdS spherical nanoparticles were dispersed on g-C3N4 nanosheets by hydrothermal method. The optimal loading of CdS on g-C3N4 nanosheets was determined by testing the degradation performance of the composite photocatalysts with different loading amounts. The degradation performance was tested by simulating sunlight using a 700-800 W xenon lamp equipped with a 420 nm cut-off filter, which showed that the degradation of MB by 7% CdS/g-C3N4 photocatalyst was 90.7% for MB. It indicates that concentrated acid treatment and loading of CdS nanoparticles can significantly improve the photocatalytic activity of g-C3N4 nanosheets, which is attributed to the enhancedup conversion function of g-C3N4 by loading CdS to enhance the response range and ability of g-C3N4 in visible light and the photogenerated electron-hole pair separation rate by loading CdS, thus improving the photocatalytic performance of the composite.

Complete Degradation of Glassy Carbon Microspheres into Carbon Nanostructures: Implications for Sensing

Glassy carbon (GC) is a well-known carbon material consisting of sp2 hybrid carbon and having fullerene-like nanostructures. GC is recognized to have several advantages, such as good electroconductivity, low density, gas- and liquid-impermeability, high resistance to graphitization, unusual hardness, and good chemical inertness. However, in our recent investigation, we found for the first time that microsized GC microspheres could be completely transformed into nanostructures by concentrated nitric acid (HNO3) treatment, showing that GC did not have good chemical inertness upon exposure to oxidizing acids such as HNO3. The resultant products contain large amounts of GC-based graphene-like quantum dots, graphene-like oxide nanosheets, and some non-degradable graphite-like nanoparticles. This work not only provides an insight into chemical properties and structures of GC but also suggests an easy and efficient way to obtain strongly fluorescent and electrochemiluminescent carbon-based quantum dots implicated for sensitive chemo- and bio-sensors.

Fluorescence enhancement induced by sulfuric acid intercalation on melem-based polymer

Fluorescent materials have achieved a great success in the fields of biomedicine, photonic devices, light-emitting diodes and others; however, millions of fluorescent materials lose their emission properties owing to aggregation-caused quenching (ACQ) effect, especially in solid state. Herein, we report the enhanced fluorescence of Melem-based polymer film via sulfuric acid modification. We propose a new strategy for maintaining fluorescence in the aggregated state by sulfuric acid intercalation, which separate the fluorophores and avoid the self-quenching. The Melem-based polymer is synthesized through a simple liquid phase reaction, and exhibits excellent fluorescence in the aggregated state after treatment with concentrated acid. This anion intercalation represents a general strategy to avert ACQ effect for existing intrinsic fluorescent materials.

The alleviation of lignin inhibition on enzymatic hydrolysis of cellulose by changing its ultrastructure

Lignin is regarded as the primary factor that inhibits enzymatic hydrolysis of cellulose. However, the impact of cellulose ultrastructure on the inhibition of lignin during enzymatic hydrolysis is still unclear. In this work, the addition of lignin during enzymatic hydrolysis of cellulose with different ultrastructure was investigated. Furthermore, the influences of changing cellulose ultrastructure on cellulose conversion of pine after hydrothermal treatment (HT) without and with additives (2-naphthol (2 N) and phloroglucinol (PL)) were explored in detail. The results showed that enzymatic hydrolyzability of allomorphic cellulose was strongly inhibited by lignin. In contrast, a small inhibition degree of lignin was observed for amorphous cellulose. Surprisingly, the cellulose conversion of HT treated pine was dramatically decreased (18.45–6.25%) after ball-milling treatment (BM), while it was significantly increased (18.45–74.49%) after concentrated phosphoric acid treatment (CP). In addition, the addition of 2 N or PL during HT could promote or inhibit cellulose conversion due to the changes in the condensation degree of lignin. These results indicated that the physiochemical structure of lignin has a significant effect on cellulose hydrolysis. More importantly, the increasing degree of cellulose conversion was enhanced in sequence from HT+PL (6.19–35.00%), HT (18.45–74.49%), to HT+ 2 N (21.12–92.30%) after CP, which was attributed to the reducing lignin condensation and changing cellulose ultrastructure. Overall, this work demonstrated that the inhibition degree of lignin was highly dependent on the cellulose ultrastructure.

Highly sensitive graphene ammonia sensor enhanced by concentrated nitric acid treatment

The ammonia (NH3)-sensing performance of graphene gas sensor treated with concentrated nitric acid (HNO3) was systematically studied in this paper. The performance of graphene gas sensor has been significantly improved after simple immersion in concentrated HNO3 (65 wt%) at a certain temperature (52 °C). In the test concentration range (20 ∼ 100 ppm), the NH3-response of the treated graphene gas sensor is increased by 3.02 ∼ 3.358 times, and the theoretical limit of detection (LOD) is 0.027 ppm (27 ppb). The treated sensor also shows good repeatability, stability and ultra-high selectivity. In the same concentration test, the response of NH3 is dozens of times higher than others. XPS, FTIR and Raman spectra analysis revealed that the nondestructive introduction of oxygen-containing functional groups (NO2–) onto graphene surface by concentrated HNO3 treatment is considered to be the key to improve the NH3-sensing performance of graphene gas sensors. NO2– groups are supposed to provide abundant O atoms as effective adsorption sites to assist graphene to adsorb NH3, thus improving the NH3-response of graphene. A simple, effective and low-cost method is proposed to improve the NH3-sensing performance of graphene in this work, which is of great significance to promote the practical application of graphene gas sensor.

Potato peel waste-derived carbon-based solid acid for the esterification of oleic acid to biodiesel

Bio-waste valorization to generate carbon-based solid acid catalysts for biodiesel production from the low-grade, highly acidic feedstocks has been a research hot spot over the last decade. In this study, an abundant bio-waste from the household kitchens, restaurants, and food processing industries, potato peel (PP), was adopted as a raw material for the production of a solid acid catalyst (SO 3 H-PPAC). Firstly, PP was mixed with ZnCl 2 and activated at 450 °C for 1 h to obtain a porous carbon material (PPAC), which was subsequently sulfonated via concentrated sulfuric acid treatment. Various physicochemical techniques, such as XRD, N 2 physisorption measurements, FTIR spectroscopy, and high-resolution transmission electron microscopy (HR-TEM), were used to study the structural properties of the prepared materials. The catalytic behavior of the catalyst was tested in the acid-catalyzed esterification of oleic acid with methanol for biodiesel production. The combination of the high surface area of 827.7 m 2 / g and high concentration of acidic active sites of 1.6 mmol/g led to a high oleic acid conversion efficiency of 97.2% at 5 wt.% SO 3 H-PPAC, methanol/oleic acid molar ratio of 12:1 at 80 °C after 2.5 h. Moreover, the kinetic results unveiled that the esterification reaction obeyed the pseudo-first-order kinetic model, with an activation energy of 32.9 kJ/mol. Importantly, SO 3 H-PPAC has satisfying recyclable features and could maintain ∼ 70 % of its initial catalytic performance in the 5 th catalytic run. • Sulfonated carbon catalyst was synthesized from potato peel by ZnCl 2 activation and sulfonation. • The obtained catalyst exhibited high surface area of 827.7 m 2 g -1 . • Synthesized catalyst used in oleic esterification acid and afforded a high conversion of 97.2%. • The catalyst maintained ∼ 70 % of its initial catalytic performance in the 5 th catalytic run.

The use of increasing proportions of N-NH4+ among the total applied inorganic N to improve acidification and the nutritional status and performance of blueberry plants in soilless culture

The increased demand for blueberries and limited availability of low-pH soils have led to the increased use of soilless culture systems. The objective of this study was to evaluate the effect of a wide range of RNH4+ [RNH4+ = 100*N-NH4+/(N-NH4++N-NO3−)] values on the acidification of the growth medium and the nutrient status and performance of blueberry plants. RNH4+ treatments of 25% (AN25, control), 50% (AN50) and 100% (AN100) and a 25% N-NH4+ plus concentrated sulfuric acid (AN25-acid) treatment were applied by fertigation to southern highbush blueberry plants (Vaccinium corymbosum, cv. Sunshine Blue) grown in a soilless substrate (50% tuff, 25% peat, 25% coconut coir). The original solution for the AN25-acid treatment was adjusted to a constant pH of 4.5. The pH and mineral concentrations in the leachate, pH of the growth medium and mineral and chlorophyll concentrations in the leaves were monitored periodically. Plant water uptake was monitored periodically and foliage volumes were calculated at the end of the growing season. Application of high levels of RNH4+ decreased the pH of the leachate and medium to below 5.5 and increased the concentrations of Fe, Mn and Zn in the leachate, as compared to the control treatment. Those treatments also increased the chlorophyll concentrations, total plant water uptake, foliage volumes and leaf Mn concentrations relative to the control treatment. The effects of the high-RNH4+ treatment on acidification and plant performance were not significantly different from the effects of the commonly used AN25-acid treatment. It seems, therefore, that the increased RNH4 reduced the pH of the growth medium to the required level for blueberry production, providing a safer and more environmentally friendly alternative to the use of sulfuric acid.

Transition of cellulose supramolecular structure during concentrated acid treatment and its implication for cellulose nanocrystal yield

Cellulose nanocrystals with cellulose I and II allomorphs (CNC-I and CNC-II) were prepared from eucalyptus cellulose I substrate by controlling the sulfuric acid hydrolysis conditions, including acid concentration (56–64 wt%), reaction temperature (45 or 60 °C) and time (10–120 min). The crystalline structures were verified by XRD and 13C-NMR. CNC-II only appeared at very restricted reaction conditions. The rapid cellulose supramolecular structure transition under sulfuric acid concentration of around 60 wt% resulted in an abrupt change in CNC yield. A maximal CNC yield of 66.7% was obtained at acid concentration of 58 wt% and reaction temperature of 60 °C. CNC-I exhibited spindle-shape, while CNC-II showed a twisted strip structure. The state of order in cellulose during the acid hydrolysis process has been studied using a coagulation method. A tentative model of CNC-I and CNC-II formation was then proposed. This work provided significant knowledge for the production of CNCs with high yield and controllable allomorph.

In-situ functionalization of tetrahedral amorphous carbon by filtered cathodic arc deposition

Modification of the surface chemistry of carbon-based nanomaterials is often necessary in order to embrace their full potential. A wide variety of different post-fabrication treatments, such as acid, oxidizing plasma and heat treatments have been described in the literature. However, their specific effects on the materials surface chemistry is typically only vaguely disclosed. Here we report an in-situ method to functionalize tetrahedral amorphous carbon (ta-C) thin films by introducing high purity oxygen into the vacuum chamber during the film fabrication. Additionally, we analyze and compare the material properties of the resulting thin films to those of nitric acid and oxygen plasma treated as well as those with no treatment at all. Using x-ray absorption spectroscopy (XAS), we show that in-situ functionalizing decreases the sp2 content of the surface and increases the amount of carboxyl-like functionalities. Subsequent oxygen plasma treatment further decreases the sp2 fraction and ketone/aldehyde content as well as increases the amount of carboxyl groups. The same trends are observed with the reference ta-C exposed to oxygen plasma treatment. For both materials, a concentrated nitric acid treatment has only a subtle effect on the surface chemistry. Capitalizing on this knowledge, we can selectively produce materials with higher surface loading of specific functional groups, paving the way for application specific material fabrication.

BLACK AND WHITE LAHAR AS INORGANIC SUPPORT FOR THE IMMOBILIZATION OF YEAST INVERTASE

Volcanic ejecta or lahar can serve as an inorganic support for the immobilization of invertase. Pampanga and Bicol lahar samples were pretreated by ignition at 550oC for 5 hrs followed by concentrated hydrochloric acid treatment, activatedby reaction with aminopropyltriethoxysilane (APTS) and then covalently bound to invertase using glutaraldehyde as linker. Chemical tests confirmed the attachment of APTS to lahar and glutaraldehyde to silanized lahar. The quantity of immobilized invertase on Pampanga white, Pampanga black and Bicol black lahar were 98.73%, 96.73% and 84.27%,respectively. Conditions for maximum activity of invertase immobilized on Pampanga white lahar were pH 3.5, 45oC and 0.3 M sucrose concentration. The Kmand Vmaxfor free invertase and immobilized invertase on Pampanga white lahar were 2.37 M and 48.75 mmol/min, and 3.88 M and 38.87 mmol/min, respectively. Invertase bound to Pampanga white lahar was most stable towards repeated and continuous use and towards storage with intermittent use as indicated by its relatively greater activity.

A Study on the Aseptic Germination Method for <i>Rosa rugose</i> Seeds

In order to find a method to break dormancy of Rosa rugose seeds and interspecific hybrid seeds between Rosa rugose and Rosa hybrid quickly, and accelerate the breeding process of interspecific hybridization between Rosa rugose and Rosa hybrid, the influence of concentrated acid, seed maturity, GA3 (gibberellin) and low temperature (4°C) on seed germination of Rosa rugose from Muping was researched under aseptic condition. The results showed that aseptic germination can significantly shorten the germination time of Rosa rugose seeds and raise its germination ratio. Before inoculation, concentrated acid treatment greatly increased the germination rate and reduced the contamination rate of the seeds. The higher the degree of maturity of seeds is, the lower the germination rate would be, and the best time for seed to aseptic germination is 60 d after pollination. The addition of GA3 in 1/2MS medium could promote seeds germination better, and when the concentration of GA3 was 0.15 mg/L, the seed germination ratio was the highest; the germination time decreased and the seed germination ratio increased gradually as the treatment time at 4°C lasted longer.

Purification and dispersibility of multi-walled carbon nanotubes in aqueous solution

In this paper, the pristine multi-walled carbon nanotubes (P-MWCNTs) were purified either by the high temperature treatment (HT-MWCNTs) or by concentrated acid treatment (CA-MWCNTs). The HT-MWCNTs were prepared by heating at 500°C, while the CA-MWCNTs were treated by the mixture of concentrated nitric and sulfuric acids taken in a volume ratio of 3: 1. Ultrasonic processing and surfactants were utilized to achieve homogenous MWCNTs suspensions. The HT-MWCNTs and CA-MWCNTs were characterized by thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FT-IR). Among these three MWCNTs, the prepared homogeneously dispersed MWCNTs suspensions were characterized by UV–Vis absorbency and transmission electron microscopy (TEM). Finally, the dispersion mechanism was discussed. The results showed that both high temperature treatment and concentrated acid treatment can be used for purification of the P-MWCNTs, removing the amorphous carbon and other impurities. In these suspensions, the purified MWCNTs showed a better dispersibility in aqueous solution. The high temperature treatment was a kind of physical purification treatment method and it just burned the amorphous carbon away and strengthened the structure of MWCNTs, while the concentrated acid treatment was a chemical purification treatment method and this chemical treatment method grafted more effective groups to improve the dispersibility of MWCNTs.

Isotherm, kinetics, and process optimization for removal of Remazol Brilliant Blue dye from contaminated water using adsorption on acid-treated red mud

Red mud, which is a waste product from alumina production, has been utilized after activation with concentrated sulphuric acid treatment for removal of Remazol Brilliant Blue (RBB) dye from dye-contaminated water to investigate its potential as a low-cost adsorbent. The activation has enhanced the surface area of red mud from 20.2 to 32.28 m2/g, thus enhancing its adsorption capacity. The effect of initial dye concentration, contact time, initial pH and adsorbent dosage on percentage removal of dye using concentrated sulphuric acid-treated red mud (CATRM) was investigated. The ranges of these variables for optimization were selected based on batch studies. Acidic pH favoured adsorption and 300 min contact time was found to be suitable for attainment of equilibrium under shaking conditions of 145 rpm. Langmuir isotherm model has been found to represent the equilibrium data for RBB-CATRM adsorption system better in comparison with Freundlich model. The adsorption capacity of CATRM was found to increase with the increase in temperature, and at 40°C, it was found to be 125 mg dye/g of CATRM. The adsorption kinetics was represented by second-order kinetic model, and the kinetic constant was estimated to be 0.0063 g/mg min. Factors affecting the adsorption process were optimized by response surface methodology based on experiments designed as per central composite design. The effects of individual variables and their interaction effects on dye removal were determined. The results of the study showed that dye removal efficiency of almost 100% can be obtained with optimal conditions of initial dye concentration at 105 mg/l, red mud dosage of 2.05 g/l, initial pH of 1 and temperature of 31.65°C. pH and temperature were found to have high interaction effect on adsorption.

Responses to Seed Dormancy Breaking Treatments in WildHibiscusspecies

To determine the most suitable means of overcoming seed dormancy in seven wild spe-cies of Hibiscus (Hibiscus acetosellaWelw. ex Fic., Hibiscus calyphyllus Cav., Hibiscus surattensis L., Hibiscus lobata Kuntze, Hibiscus radiatus Cav, Hibiscus vitifolius L., Hibiscus panduriformis Burm. f) and their accessions, seeds were exposed to various pre-treatments such as scarification with hot water and sulphuric acid for varying du-rations. Treated seeds were evaluated for their viability to assess the impact of given treatments. The results revealed that concentrated sulphuric acid scarification treatment for 10 min was highly effective in breaking hard-seed dormancy in all accessions of H. calyphyllus.Concentrated sul-phuric acid treatment for 10–20 min in H. vitifoli-us; 25 min in H. surattensis; 30 min in H. radiatus; 5min in H. lobatus was effective in overcoming hardseededness. Hot water treatment at 80°C for 10 min was effective in H. acetosella and H. pan-duriformis. However in H. panduriformis concen-trated acid treatment for 5min was equally effec-tive as hot water treatment. This study therefore clearly demonstrates the efficacy of concentrated sulphuric acid pre-treatment for 10–30 min and hot water treatment at 80°C for 10 min as an ef-fective enhancer of seed germination of wild spe-cies of Hibiscus. Because of the variation in the seed size and degree of hardseededness among the species no single treatment can be recom-mended for breaking dormancy in all species.

Highly Conductive PEDOT:PSS Treated with Formic Acid for ITO-Free Polymer Solar Cells

We proposed a facile film treatment with formic acid to enhance the conductivity of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) by 4 orders of magnitude. The effect of formic acid concentration on conductivity was investigated; conductivity increased fast with increasing concentration up to 10 M and then increased slightly, the highest conductivity being 2050 S cm(-1) using 26 M concentration. Formic acid treated PEDOT:PSS films also exhibited very high transmittances. The mechanism of conductivity enhancement was explored through SEM, AFM, and XPS. Formic acid with its high dielectric constant screens the charge between PEDOT and PSS bringing about phase separation between them. Increased carrier concentration, removal of PSS from the film, morphology, and conformation change with elongated and better connected PEDOT chains are the main mechanisms of conductivity enhancement. ITO-free polymer solar cells were also fabricated using PEDOT:PSS electrodes treated with different concentrations of formic acid and showed equal performance to that of ITO electrodes. The concentrated acid treatment did not impair the desirable film properties as well as stability and performance of the solar cells.

Reclamation of Spent Automobile Engine Lubricating Oil

In this study, some of the property reclamation methods for spent lubricating oil (SLO) were demonstrated. Firstly, 3.5 L of SLO was subjected to physical methods such as natural settling, sedimentation, magnetisaton and filtration to remove all forms of particles irrespective of size. The remaining samples were either subjected to acid treatment using concentrated sulphuric acid or solvent treatment using methanol, butanol and toluene including their blends to study their performance in the extraction process to recover the lubricating oil. The key parameter considered is the volume ratio of solvent/acid to used lubricating oil. In all, 5, 10, 15 and 20 ml respectively were used for each of the treatments. Activated carbon was equally introduced as adsorbent. A ratio of 4:1 (B20 formulation) for the treated spent oil and additives was used in this study for the final reclamation of the spent oil. The performance of each of the treatments process was investigated by subjecting all samples to laboratory analysis using American Standards for Testing and Methods (ASTM) to evaluate certain lubricating/tribological properties such as density, viscosity, pour point, cloud point etc. Both virgin oil and used oil were also simultaneously subjected to analysis with other recovered oil samples. The results suggest that the oil recovered by solvent treatments, particularly methanol exhibited better lubricating properties and can be rendered as good as virgin lubricants with the addition of certain additives. However, acid treatment demonstrated improved colour and appearance recovery compared to solvents.