Acid Neutralizing Capacity Research Articles

Evaluating acid resistance of Portland cement, calcium aluminate cement, and calcium sulfoaluminate based cement using acid neutralisation

Cementitious materials are alkaline in nature. As a result, they are prone to neutralisation reaction by acids and possible deterioration. Among the existing binders, the acid resistance of calcium sulfoaluminate (CSA) cement is not well explored. Moreover, the phase composition of CSA cement varies significantly to reflect its expansive and non-expansive characteristics. In this article, the effect of chemical composition on acid resistance is evaluated in terms of acid neutralisation capacity (ANC) or acid consumption, providing a novel approach to evaluate the durability of CSA cements in low pH environment. This research focuses on evaluating citric acid and sulfuric acid resistance of Portland cement (PC), high ye'elimite CSA cement (CSA (HY)), and calcium aluminate cement (CAC). The tests were performed on monolithic specimens as well as powdered hydrated samples using an autotitrator. The acid resistance of three binders could be evaluated from total acid consumption and predicted based on early period of test depending on a binder's acid - pH interaction curve. Furthermore, a procedure was developed to correlate powder and monolithic tests.

Seasonal variations of low molecular alkyl amines in PM2.5 in a North China Plain industrial city: Importance of secondary formation and combustion emissions

Atmospheric amines have unique acid-neutralizing capacity and play an important role in atmospheric chemical reactions. An integrated observation of PM2.5 samples (from Dec 2015 to Nov 15, 2016) was conducted in a typical industrial city (Xuzhou), China. Concentrations of total measured amines (∑amines, including methylamine (MA), ethylamine (EA), dimethylamine (DMA), propanamine (PA) and trimethylamine (TMA) + diethylamine (DEA)) were 172.0 ± 98.2 ng m−3, accounting 1.5 ± 0.6 ‰ of PM2.5 mass. ∑amines were higher in winter (249.0 ± 112.3 ng m−3) and spring (192.4 ± 75.9 ng m−3) than in summer (114.7 ± 33.3 ng m−3) and autumn (103.7 ± 34.3 ng m−3). Concentrations of MA and EA (the dominant amines) were highest in winter, while DMA, PA and TMA + DEA showed opposite seasonality. EA/MA ratios ranged from 0.04 to 8.7 with a median value of 0.3, and the averaged EA/MA ratio was 2.0 in winter, indicating large contribution of EA. Environmental factors including temperature (T), relative humidity (RH) and atmospheric oxidizing capacity (O3 and Ox represented) were found to influence concentrations of amines in PM2.5. The Positive Matrix Factorization (PMF) model identified secondary products (41.6 %), combustion emissions (39.8 %), soil and waste incineration emissions (13.2 %) and biological emissions and aging products (5.4 %) as the 4 sources of amines in PM2.5. MA was mainly secondary products (82.5 %) and had high contribution of local secondary formation, while EA was mainly derived from combustion emissions (83.7 %) and influenced by regional transportation. In winter, combustion emissions (including coal combustion, biomass burning and traffic emissions, contributed 57.7 %) surpassed secondary products (31.6 %) as the predominant sources of amines, especially under the influence of regional transportation (75.7 %).

An expert opinion on antacids: A review of its pharmacological properties and therapeutic efficacy

Acidity caused by common gastric conditions such as non-ulcer dyspepsia, duodenal ulcer, gastric ulcer, stress gastritis, gastroesophageal reflux disease (GERD), pancreatic insufficiency, bile acid-mediated diarrhea, biliary reflux, and constipation can be treated by administration of potent and efficacious acid suppressant (anti-secretory) agents such as antacids, histamine H2 receptor blockers, and proton pump inhibitors (PPIs). Antacids provide symptomatic relief from hyperacidity as well as other associated conditions by neutralizing the gastric acid directly, thereby raising the gastric pH, attenuating the pepsin activity, restoring acid-base balance, and increasing prostaglandin and bicarbonate secretion. The effectiveness of antacids is determined by its acid neutralizing capacity (ANC) and buffering capacity. Antacids containing a combination of aluminum hydroxide, magnesium hydroxide, and other ingredients such as those present in Digene showed better therapeutic efficacy even at low dosage with fewer side effects, persistent increase in gastric pH, faster and longer duration of pain relief, and fast relief from gas. Various clinical studies suggest that to obtain fast symptomatic relief, the treating physician can utilize antacids with the highest neutralizing capacities like Digene.

Nitrogen and sulfur deposition reductions projected to partially restore forest soil conditions in the US Northeast, while understory composition continues to shift with future climate change.

Human activities have dramatically increased nitrogen (N) and sulfur (S) deposition, altering forest ecosystem function and structure. Anticipating how changes in deposition and climate impact forests can inform decisions regarding these environmental stressors. Here, we used a dynamic soil-vegetation model (ForSAFE-Veg) to simulate responses to future scenarios of atmospheric deposition and climate change across 23 Northeastern hardwood stands. Specifically, we simulated soil percent base saturation, acid neutralizing capacity (ANC), nitrate (NO3 -) leaching, and understory composition under 13 interacting deposition and climate change scenarios to the year 2100, including anticipated deposition reductions under the Clean Air Act (CAA) and Intergovernmental Panel on Climate Change-projected climate futures. Overall, deposition affected soil responses more than climate did. Soils recovered to historic conditions only when future deposition returned to pre-industrial levels, although anticipated CAA deposition reductions led to a partial recovery of percent base saturation (60 to 72%) and ANC (65 to 71%) compared to historic values. CAA reductions also limited NO3 - leaching to 30 to 66% above historic levels, while current levels of deposition resulted in NO3 - leaching 150 to 207% above historic values. In contrast to soils, understory vegetation was affected strongly by both deposition and climate. Vegetation shifted away from historic and current assemblages with increasing deposition and climate change. Anticipated CAA reductions could maintain current assemblages under current climate conditions or slow community shifts under increased future changes in temperature and precipitation. Overall, our results can inform decision makers on how these dual stressors interact to affect forest health, and the efficacy of deposition reductions under a changing climate.

Speciation, leachability and bioaccessibility of tungsten in tungsten ore processing residue.

Tungsten ore processing residue (TOPR) poses a potential risk due to tungsten (W) leaching. However, the leachability of W in TOPR is not well understood. Herein, the mechanism of W leachability from TOPR was investigated using complementary characterization techniques and leaching experiments. Our X-ray absorption near edge structure (XANES) analysis resolved wolframite in TOPR with a distorted octahedral coordination. The sequential extraction procedure showed that 78% of mobile fraction W in TOPR were bound to Fe oxides, and consequently W leachability was positively correlated with dissolved Fe concentration as evidenced by the general acid neutralizing capacity (GANC) test. The GANC results showed that the W release was negatively correlated with Ca concentration due to CaWO4 precipitation. The in vitro gastrointestinal procedure (IVG) results indicated that organic acids, abundant in fruits and vegetables, significantly improved the bioaccessibility of W from 10% to 20% of total W in TOPR. As a consequence, accidental ingestion of TOPR with a chemical daily intake at 0.8mgkg-1 day-1 evidenced its emerging concern in the environment and human health.

Development and Evaluation of Kukkutandatvak bhasma tablet by using Dry Granulation Techniques

Aims: This study aimed to formulate and evaluate Kukkutandatvak (Hen Eggshell) bhasma tablet intended for optimum disintegration and release in the gastrointestinal tract. Methods and Material: Calcium content in Kukkutandatvak bhasma was determined using the titrimetric method. 9 formulations (F1 to F9) were prepared with Polyvinylpyrrolidone and SGS as super disintegrants. The granules were then evaluated for angle of repose, bulk density, tapped density, Hausner's ratio and Carr's index. The granules were then converted into caplet shaped tablets and were evaluated for uniformity of weight, drug content, friability, Hardness, Disintegration (in a sec) and % drug release. Results and Discussions: Calcium content in Kukkutandatvak bhasma was found to be 98%. The granules were found to be free-flowing and compressible. The Kukkutandatvak bhasma tablet had good strength and lower disintegration time (less than 135 sec), indicating a better balance between the binding and disintegration properties. The antacid activity of the tablet was evaluated by preliminary antacid test, i.e. acid-neutralizing capacity test and Rosset-Rice test. Conclusions: It was observed that Kukkutandatvak bhasma tablet (500 mg) prepared by both methods comply with Preliminary Antacid Test U.S.P. The tablet prepared neutralized 15.15 mEq of respectively in just 9.25min.

Phosphorus removal by steel slag from tile drainage water: Lab and field evaluations

Basic oxygen furnace (BOF) and blast furnace (BF) steel slags are well suited for phosphorous (P) removal from nonpoint sources such as agricultural runoff. However, the reported mechanism(s) of removal varies from study to study which complicates implementation for unique environmental conditions that may interfere with the removal mechanism(s). This work compared laboratory column experiments and field filter experiments to provide insights on the influence of relevant field conditions (water alkalinity, slag grain size distribution, BF:BOF slag ratio, and water stagnation) on P removal by BF and BOF steel slag mixtures. Alkalinity was the most influential variable in lab-scale slag columns that received 250 mg/L alkalinity water and achieved complete P removal throughout the 3-h experiment, while identical columns receiving 500 mg/L alkalinity water averaged 52% P removal and only 14% removal after 2.5 h. Batch regeneration and adsorption experiments were conducted on the exhumed BOF/BF slag mixture from the field filter to evaluate strategies for increasing field P removal capacity. The adsorption capacity of steel slags was effectively regenerated by 0.01 M Al2(SO4)3, which allowed for an additional 34% P removal in batch adsorption tests. The acid neutralization capacity of slag samples was effectively regenerated by 1 M NaOH, which allowed previously expended slag to reach a pH of 9.7 even in high alkalinity test water. The results presented here show that BF slag and Al2(SO4)3 regeneration of BF slag is best suited for high alkalinity influent conditions and removes P through adsorption while BOF slag and NaOH regeneration perform best under low alkalinity conditions and removes P through mineral precipitation.

Study on the accelerated carbonation of MSWI fly ash under ultrasonic excitation: CO2 capture, heavy metals solidification, mechanism and geochemical modelling

The current carbonation technology of municipal solid waste incineration fly ash (FA) has disadvantages such as low carbon sequestration efficiency, harsh conditions, and complicated equipment. An ultrasonic chemical method coupled with wet-carbonization technology is proposed. The effects of the FA ultrasonic carbonation (UC) method on CO2 capture, heavy metals (HMs) release and solidification were investigated, and geochemical model of FA was explored. The results showed that UC improved the CO2 capture capacity, and the carbonation efficiency increased from 14.1 % to 18.8 % because the ultrasonic physical and chemical excitation improved the mass transfer efficiency and strengthened the gas–liquid-solid three-phase carbonation reaction. UC inhibited the release of Pb and Zn into the liquid phase (0.002 mg/L and 0.004 mg/L) and increased the solidification efficiency of Pb and Zn in FA (99.99 % and 100 %) because free Pb and Zn converted carbonates completely. UC FA had a single component, small particle size, high degree of homogenization, and contained slender nano-CaCO3 crystals. The acid neutralization capacities of original FA, FA4, and FA9 were 10, 8, and 3 meq/g because the carbonation reaction neutralized the alkaline substance. The content of carbonate minerals was the highest in UC FA and the pH of carbonate-minerals controlled dissolution/precipitation was mainly between 6 and 10. The HMs were in a soluble state (pH < 6) and the amphoteric HMs were affected by soluble hydroxides, the leaching concentration increasing (pH > 10). Therefore, UC FA had the potential of economical, environmentally friendly, and resource-based applications when avoiding strong acid and alkali application scenarios.

The potential of using alkaline gold mine tailing as a cover material to mitigate AMD formation from acidic gold mine tailing pile at Sabie-Pilgrim's Rest Goldfields, South Africa.

Acid mine drainage (AMD) caused by the oxidation of sulphide minerals found in mine waste is a global environmental concern, especially in water-restricted countries with heavy mining industries. Implementing AMD treatment and prevention programs can be extremely expensive, hence the need to identify environmentally sustainable treatment and preventative techniques to mitigate the potential of AMD formation. Soil covers and blends have been identified as an attractive approach. However, prior studies on the characteristics of the soils concerned and the acid-neutralisation rate should be carried out before considering the implementation of a soil cover or blending system to mitigate AMD formation. This study evaluated the acid generation capabilities of acidic gold mine tailings (AG), alkaline gold mine tailings (AN) and blends (MIX25, MIX50). Acid-base accounting (ABA), net acid generation (NAG) and acid-buffering characteristic curve (ABCC) test methods were used to evaluate the acid-generating and acid-neutralising capabilities of AG, AN, MIX25 and MIX50 samples. Leach column tests were conducted using alkaline gold mine tailings (AN) as the top pH neutralising cover (COV25) to determine the potential of the alkaline gold mine tailing to serve as a pH neutralising cover material to prevent and treat AMD generated by the acidic gold mine tailings. The ABA, NAG and ABCC results showed that AN has a high acid-neutralising capacity while AG has the potential to generate acid. The results further indicated that the AN to AG blend ratio of 1:3 by weight (MIX25) would neutralise the acid generated by AG. Leach column experiment (COV25) found that using AN as a pH neutralising cover would be a feasible option.

Rapid improvement of lake acid–base status in Atlantic Canada following steep decline in precipitation acidity

Policy measures resulted in reductions in acidic emission of sulfur and nitrogen in North America. Here, we conducted trend analyses on a 37-year database for atmospheric depositions and lake ( n = 78) chemistry in the provinces of Nova Scotia, New Brunswick, and Newfoundland and Labrador, in Canada. Sulfate, and particularly nitrate deposition, began to decrease strongly around the year 2000, resulting in strong pH increases in precipitation. Recovery was observed in most lakes with significant increases in pH and Gran alkalinity (AlcG). A piecewise regression approach detected coherent breaks and overlapping confidence intervals in the break years for precipitation pH and lake AlcG (to a lesser extent for lake pH), suggesting a rapid lake response to the sudden changes in acidic inputs. However, an increase in organic acid after 2000 decreases the rate of acid neutralizing capacity recovery nearly by half in about a third of the studied lakes. Despite the positive pH and AlcG trends, a significant proportion of lakes still have pH and calcium values below the recommended thresholds for aquatic life.

Red mud-biochar composites (co-pyrolyzed red mud-plant materials): Characteristics and improved efficacy on the treatment of acidic mine water and trace element-contaminated soils

The use of commercially sourced dopants for synthesizing biochar-based composites could be economically undesirable. The current work aimed to explore the possibility of making low-cost biochar-based composites using red mud (an industrial waste from alumina production) as dopants. Two types of red mud were used: one from a Bayer process and another from a sintering process. Different techniques (wet chemical, magnetic, SEM-EDS, FTIR, XPS and XRD analyses) were adopted to characterize the synthesized red mud-biochar composites, along with the pristine biochar. The composites were superior to the pristine biochar in terms of acid neutralizing capacity, specific surface area, and degree of magnetization. Two laboratory simulation experiments were conducted to assess the improved efficacy of the composites on the treatment of acidic mine water and mine water-contaminated soils. In general, application of the composites resulted in a significantly higher removal rate of mine water-borne trace elements compared to the pristine biochar treatment. The composites also had better effects on immobilizing the soil-borne trace elements and weakening the uptake of trace elements by the test vegetable plant species grown in the composite-treated soils, as compared to the pristine biochar-treated soil. By comparison, the sintering red mud-biochar composite had a generally better performance compared to the Bayer red mud-biochar composite.

Acid Neutralizing Capacity and Immunomodulatory Activity of Citrullus Colocynths

The &lt;em&gt;Citrullus colocynthis (L.) Schard&lt;/em&gt; from Cucurbitaceae family having a properties of ancient remedies on many diseases. This research work has focused on the to detect the preliminary antacid test (PAT), acid neutralizing capacity (ANC) ,buffer capacity(BC) consisting of &lt;em&gt;Citrullus colocynthis &lt;/em&gt;and compared with Gelusil tablet as a standard along with this determined the immunomodulation activity. The PAT of the ethyl acetate,aqueous and alcoholic extracts of fruit were found in range of pH 3.90 ± 0.07 to 6.36 ± 0.18 and ANC located in between 24.23 ± 00 to 27.86 ± 76 mEq/gm. Further the value at which the pH of an extracts changes over period founded in between 30 min to 45 min. The investigation of immunomodulation activity carried out by phagocytosis assay of &lt;em&gt;C. albican&lt;/em&gt;. This research has reached to conclusion that is the ethanolic extract yielded a greater result of ANC and aqueous extract determined higher buffer capacity comparative with standard antacid (Gelusil). Moderate immune stimulation shown by the ethanolic extract with 5 and 10 mg/ml of concentration.

Formulation and evaluation of raft forming pirenzepinedihydrochloride floating tablets for peptic ulcer

Objective: Over past few decades, Peptic ulcer disease remains a common condition despite the lots of novelty in treatment. The objective of this research work was to formulate gastro retentive floating tablet by raft approach using Pirenzepine dihydrochloride (PNZ) as drug candidate. Formulation also contained a raft forming agent (sodium alginate) along with alkalizing agents (Calcium carbonate and Sodium Bicarbonate). Raft strength was only affected by the amount of Raft forming agent, Calcium carbonate and Sodium Bicarbonate. Method: Tablets were prepared by direct compression method and evaluated for raft strength, acid neutralization capacity, weight variation, % drug content, thickness, hardness, friability and In vitro drug release. Experimental work: A Box Behnken design was used in present study for optimization. Amount of gel forming agent, amount of cross-linkingagentsand floating agent were selected as independent variables. Raft strength, Acid neutralization capacity, and drug release were selected as dependent variables. Result: Raft strength, Acid neutralization capacity and In vitro drug release of all the experimental batches were found to be satisfactory. F10 batch was optimized based on maximum raft strength, good acid neutralization capacity and control drug release. Drug-excipients compatibility study showed no interaction between drug and excipients.

Formulation and evaluation of raft forming pirenzepine dihydrochloride floating tablets for peptic ulcer

Objective: Over past few decades, Peptic ulcer disease remains a common condition despite the lots of novelty in treatment. The objective of this research work was to formulate gastro retentive floating tablet by raft approach using Pirenzepine dihydrochloride (PNZ) as drug candidate. Formulation also contained a raft forming agent (sodium alginate) along with alkalizing agents (Calcium carbonate and Sodium Bicarbonate). Raft strength was only affected by the amount of Raft forming agent, Calcium carbonate and Sodium Bicarbonate . Method: Tablets were prepared by direct compression method and evaluated for raft strength, acid neutralization capacity, weight variation, % drug content, thickness, hardness, friability and In vitro drug release. Experimental work: A Box Behnken design was used in present study for optimization. Amount of gel forming agent, amount of cross-linkingagentsand floating agent were selected as independent variables. Raft strength, Acid neutralization capacity, and drug release were selected as dependent variables. Result:Raft strength, Acid neutralization capacity and In vitro drug release of all the experimental batches were found to be satisfactory. F10 batch was optimized based on maximum raft strength, good acid neutralization capacity and control drug release. Drug-excipients compatibility study showed no interaction between drug and excipients.

Analysis of gastrointestinal acid-neutralizing potency of some commercial antacid tablet formulations

In dyspepsia, formulations known as antacids are regularly used to alleviate symptoms as quickly as possible. Gastric contents are acidic; therefore, antacids are usually weak bases with the potential to neutralize excess acid and raise gastric pH accordingly. Acid-neutralizing capacity is what determines the effectiveness of an antacid. Some antacid tablets formulation from different manufacturers were tested for their acid-neutralizing capacity and effectiveness for patients in this study. The South-East region of Nigeria had pharmacies vending antacids of different brands. To remove potential bias from the study, the brands were coded A-F. Labels on all samples indicated that they would expire more than one year from now. To determine each antacid tablet's acid-neutralizing capacity, the titrimetric method was used. In terms of acid-neutralizing capacity, brands D, A, B, C, F, and E showed the greatest acid-neutralizing capacity (8.2mEq/g), and brand E showed the lowest capacity (5.7 mEq/g). An analysis of the ANC of all the tablets found that they exceeded the FDA standard of &gt;5mEq for antacids. An inexpensive, simple, and easy-to-use titrimetric method could be used routinely to monitor antacid tablet quality.

Improving sulphuric acid resistance of slag-based binders by magnesium-modified activator and metakaolin substitution

Alkali-activated slag (AAS) is an appealing alternative to ordinary Portland cement (OPC) in aggressive acid environment considering its relatively low calcium content and potential in retarding aggressive media penetration. This study evaluates the effect of reactive MgO–NaOH mixture as an activator on the performance of AAS with and without metakaolin substitution upon sulphuric acid exposure. The experimental results reveal an improved acid resistance of slag pastes with supplementary magnesium and the improvement is further enhanced with 20% metakaolin substitution. The improved effect by supplementary magnesium is not only attributed to its microstructure refinement for retarding acid penetration; but also contributed by the acid neutralisation capacity of the formed brucite and the potentially positive effect of magnesium on stabilising the AAS binding gel. Stratified silica-rich gels are formed in the metakaolin-substituted AAS, whose formation is primarily attributed to the intrinsic difference of the formed aluminosilicate gels and related to the pH value and the presence of Mg2+. Considering the dense structure of these gels, they might act as protective barriers for the AAS upon acid deterioration.

Relationships between land use and stream chemistry in the Mulberry River basin, Arkansas

AbstractThe Mulberry River in Arkansas is one of America's National Wild and Scenic Rivers and has been listed as impaired for low pH since 2008. Stream chemistry is directly related to land use and changes in land use can result in degradation of surface waters. Growth of conifers, through afforestation or conversion of native hardwood stands, has been attributed to basin acidification in several regions and may be contributing acid to the Mulberry River basin. The objective of this study was to examine the relationship between land use (i.e., coniferous forest, deciduous forest, mixed forest, and pasture) and stream chemistry of 11 tributaries of the Mulberry River over a 2‐year period. Coniferous forest land use was not correlated with stream pH, neither was stream pH predicted by coniferous forest land use. Acid neutralizing capacity (ANC) was negatively correlated with, and partially predicted by coniferous land use. Total organic carbon was negatively correlated with coniferous land use and positively correlated with deciduous land use. Deciduous land use was positively correlated with SO4 and negatively correlated with total N and NO3. Spearman's rank correlation and principal component analysis identified significant inverse relationships between stream pH and NO3 and between ANC and NO3, which may suggest that HNO3 may be the primary source of acidity within the Mulberry River basin. Although no relationships were observed between coniferous land use and pH, conifer growth may be affecting the stream buffering capacity of the basin which would increase the susceptibility of the river to acidification.

Effect of Exchanged MgAl-Hydrotalcite with Carbonate on Increases of Acid Neutralizing Capacity: A Good Candidate as an Antacid

Background: In this study, we determined the acid-neutralizing capacity (ANC) of Mg/Al-Hydrotalcite-like compounds. The MgAl-hydrotalcites were synthesized by the co-precipitation method at room temperature using Mg/Al molar ratios 2:3. The synthesized bioactive nanomaterials were characterized by various physicochemical techniques such as TG/dTG, XRD, FT-IR spectroscopy, BET/BHJ, and SEM/EDX. The antacid activity assay was done by converting both synthesized samples into liquids, 1 g of which was added to 50 ml of deionized water at 37°C under vigorous agitation. The acid-neutralizing capacity (ANC) was evaluated with 0.1N HCl. The pH was constantly measured using a pH meter and values were recorded every minute up to 35 min. In order to improve the neutralizing power of the samples, we performed an exchange of chlorides by carbonates on the MgAl-HT3 synthesized. The exchanged Mg/Al-Hydrotalcite (MgAl- HTE) showed high acid neutralization capacity (up to 13.5 mEq/g). Objective: This study aimed to synthesize MgAl-hydrotalcite-like compounds and evaluate their acid-neutralizing capacity. In order to can be good candidates for pharmaceutical applications as antacid drugs. Methods: Following methods are used in this study: - Preparation of MgAl-hydrotalcite-like compounds was done by coprecipitation methods. - Characterization of samples was done by physico-chemical techniques such as TG/dTG, XRD, FT-IR spectroscopy, BET/BHJ and SEM/EDX. - Evaluation of acid-neutralizing capacity was done by titration procedure (Dose-titration). Results: This protocol describes the preparation of MgAl-hydrotalcite-like compounds using the classical coprecipitation method. The synthesized samples were characterized by various physicochemical techniques such as TG/dTG, XRD, FT-IR spectroscopy, BET/BHJ, and SEM/EDX. The as-synthetized samples were used for the evaluation of their acid-neutralizing capacity (ANC). Further, an exchanged of MgAl-Hydrotalcite with carbonate was done for the purpose to increase the acid-neutralizing capacity. Conclusion: In summary, this study describes a simple synthesis of MgAl-Hydrotalcites compounds by a co-precipitation method at constant pH around 10, with a ratio Mg/Al = 3:2 (referred to as MgAl-HT3 and MgAl-HT2). An exchange of the chlorides (not eliminated by washing) by the carbonates was carried out on hydrotalcite with a ratio Mg/Al = 3, and the solid obtained was named MgAl-HT3E. The materials MgAl-HT2, MgAl-HT3, and MgAl-TH3E were used to evaluate antacid activity. To this end, a study was conducted to determine the acid-neutralizing capacity (ANC). As result, the MgAl-HT3E was able to increase acid-neutralizing capacity and maintain an ideal pH. These results could be interesting to prepare novel antacid drugs (due to the low cost of synthesized materials) essentially the hydrotalcite of mg/Al ratio equal to 3 because of its relatively slow kinetics of releasing basic species and therefore of its beneficial action as an antacid.

DEVELOPMENT AND EVALUATION OF RAFT FORMING GASTRO RETENTIVE FLOATING DRUG DELIVERY SYSTEM OF NIZATIDINE BY DESIGN OF EXPERIMENT

Objective: The current research involves the formulation of a sustained-release gastro-retentive drug delivery system of nizatidine. Methods: Using 33 Box-Behnken designs, about 17 experiments were performed and evaluated for various parameters like physical appearance, pH, in vitro gelling study, in vitro buoyancy study, measurement of viscosity, density measurement, gel strength, raft resilience, drug content, acid neutralization capacity, in vitro dissolution, release kinetics and stability studies. Results: All the formulations exhibited good viscosity, density less than gastric fluid, gelling capacity retained, and buoyant for 12 h. Drug content ranges from 97.98 to 99.34 %, with a long neutralization period. The buoyancy lag time was found to be in the range of 15.34 to 26.12 sec and the % drug release at 12 h was between range from 85.67 to 99.45, with the highest release exhibited by F3. All formulations displayed zero order in vitro drug release&gt;10 h with exceptional buoyancy properties. F3 was the optimized formulation and further subjected to FTIR and DSC study, concluding that compatibility of nizatidine with excipients in the formulation blend. Stability studies show no significant changes. Conclusion: Results indicate that gastric-floating formulations of nizatidine have the prospective for superior gastric residence time and sustained drug release.

ALKALINITY CONTROL PROPERTIES OF THE SOLIDIFIED/STABILIZED SLUDGE BY A LOW ALKALINITY ADDITIVE

Several chemical reactions controlling the alkalinity of solidified/stabilized sludge using a low alkalinity additive (mainly composed of gypsum and slag) are investigated experimentally. The influence of curing conditions (open air or sealed) on the alkali leaching characteristics of the treated sludge was evaluated from the viewpoint of carbonate uptake and leaching properties of cations (Ca, K, Na, Mg, Al and Si). Modified batch leaching tests were conducted for the treated sludge cured in both open air and sealed conditions to characterize the alkali and cation leaching behaviour. Mineralogical characterization was performed through X-ray diffraction (XRD) analysis, and the Calcimeter test traced the variation of carbonate amount in the treated sludge under curing. In addition, the type of hydration products in treated sludge was also estimated by the acid neutralization capacity (ANC) tests. Experimental results showed that open air curing has an effect to decrease the pH of solutions from batch leaching tests compared to sealed curing, since the sludge cured in open air contained more carbonate and less hydroxide than those cured in sealed condition. Promoting the carbonation of Ca(OH) 2 by contact with carbon dioxide could reduce the alkalinity of treated sludge. In addition, the amount of magnesium carbonates (e.g. MgCO 3 ) and the fraction of Mg ions in treated sludge could affect the pH of leached water.