User perception study for performance evaluation of domestic defluoridation techniques for its application in rural areas

Fluoride concentrations in ground water have been monitored in rural areas of Dhar and Jhabua districts in Madhya Pradesh, India. A correlation of fluoride concentration with pH, TDS and conductivity has been estimated to identify surrogate monitoring parameter. Further, fluoride removal from drinking water has been achieved by using adsorbents specially developed for domestic applications. These adsorbents have been evaluated using three different methods namely; loose adsorbent, pre-packed sachet and packed bamboo column. Comparative evaluation of these methods has been demonstrated in the laboratory and field. The stringent limit of 1mg/L for fluoride concentration in drinking water has been achieved by use of specially designed adsorbents. A feedback from end-users in Tarapur and Ukala villages of Dhar districts Madhya Pradesh regarding the adsorbents and its acceptability has been collected. User's perception regarding these household treatments reveals encouraging response for defluoridation methods. According to user's perception loose adsorbent approach emerged out as most simple, clean and safe household defluoridation method.     

An empirical model for defluoridation by batch monopolar electrocoagulation/flotation (ECF) process

Excessive presence of fluoride concentration in community water supplies can cause fluorosis that affects the teeth and bones. Batch experiments with monopolar aluminium electrodes for fluoride removal were conducted and an empirical model is developed using critical parameters such as current concentration, electrode distance, and initial fluoride concentration. Fluoride ions were removed electrochemically from solution by electrocoagulation/flotation (ECF) process. The electrolytic dissolution of aluminium anodes in water produced aqueous Al3+ species and hydrogen bubbles at the aluminium cathodes. The fluoride removal efficiency increases steadily with increasing current values from 1 to 2.5 A. In the batch monopolar ECF process, the optimal detention time (dto) was found to be 55 min when the operational parameters including initial F- concentration, current value, and inter electrode distance were respectively kept at 10 mg/l, 1.5 A, and 5 mm. The experimental results showed that the rate constant (K) for defluoridation by monopolar ECF process depends on the current concentration (I/V), electrode distance (d) and initial fluoride concentration (C0). The Al3+/F- mass ratio is found to be not significantly different between monopolar and bipolar ECF systems. Overall, the results showed that the electrocoagulation technology is an effective process for defluoridation of water.     

Defluoridation chemistry of synthetic hydroxyapatite at nano scale: equilibrium and kinetic studies

This study describes the advantages of nano-hydroxyapatite (n-HAp), a cost effective sorbent for fluoride removal. n-HAp possesses a maximum defluoridation capacity [DC] of 1845 mg F⁻/kg which is comparable with that of activated alumina, a defluoridation agent commonly used in the indigenous defluoridation technology. A new mechanism of fluoride removal by n-HAp was proposed in which it is established that this material removes fluoride by both ion-exchange and adsorption process. The n-HAp and fluoride-sorbed n-HAp were characterized using XRD, FTIR and TEM studies. The fluoride sorption was reasonably explained with Langmuir, Freundlich and Redlich–Peterson isotherms. Thermodynamic parameters such as ΔG°, ΔH°, ΔS° and E_a were calculated in order to understand the nature of sorption process. The sorption process was found to be controlled by pseudo-second-order and pore diffusion models. Field studies were carried out with the fluoride containing water sample collected from a nearby fluoride endemic area in order to test the suitability of n-HAp material as a defluoridating agent at field condition.     

Insights into isotherm making in the sorptive removal of fluoride from drinking water

The defluoridation research has thrown up many technologies, with adsorption as a popular alternative, especially among fluoride endemic habitations of the developing world. In the endeavor to develop novel adsorbents for defluoridation, the adsorption potential of hardened alumina cement granules (ALC) were examined through isotherm fitting. Though the adsorbent showed enhanced adsorption capacity at higher fluoride concentration ranges, the errors associated with linearization in isotherm fitting were also found to be increasing. The propagation of these errors was more prominent in Dubinin-Radushkevich and Langmuir models but negligible in Freundlich. The chi2 analysis, used to correlate the equilibrium experimental data and the isotherm models, also suggested poor correlations at higher fluoride concentration ranges for all the models. The procedure of linear and nonlinear regression through optimization of error functions rendered the 'best-fit' model and optimum model parameters, through sum of normalized error (SNE) values. Though ALC exhibited maximum monolayer adsorption capacity of 34.36 mgg(-1) in concentration variation studies of fluoride in the range of 2.5-100 mg l(-1) in synthetic water, it got reduced to 10.215 mgg(-1) in dose variation studies and further to 0.9358 mgg(-1) in natural ground water. Though Langmuir appeared as the best-fit model in terms of R2 in synthetic studies of different fluoride concentrations, the procedure of linear and nonlinear regression demonstrated that Freundlich was the best-fit. The nonlinear chi2 analysis together with minimum SNE values convincingly demonstrated that the equilibrium studies with dose variations of ALC offers more reliable isotherm parameters than those with high fluoride concentrations. The sorption of fluoride by ALC appeared endothermic with Freundlich adsorption capacity parameter increased from 0.5589 to 0.9939 lg(-1) in natural water and 3.980-7.5198 lg(-1) in synthetic water systems for a rise in temperature from 290 to 310 K. The study deviates from conventional methodologies of relying solely on R2 values in selecting 'best-fit' isotherm model, and basically demonstrates how the optimum model parameters like 'adsorption capacity' evolves through linear and nonlinear regression using error functions.     

冻土层下球状药包爆破方法

介绍了季节性冻土层下球状药包爆破方法以及爆破漏斗的形状。根据爆破漏斗试验结果并从冻土层受力破碎特点出发,对冻土层的破碎机理进行了定性分析。分析表明,球状药包爆炸时,冻土层的破坏类似于壳体的弯曲变形破坏。与常规的钻孔爆破法相比,采用冻土层下的球状装药爆破法,可有效地控制爆破过程的飞石,降低爆破成本,加快施工速度。文中同时给出了冻土层爆破的合理爆破参数。     

Removal of fluoride from water using iron oxide-hydroxide nanoparticles

A novel and facile method for the synthesis of uniform stoichiometric powder form of non-magnetic iron oxide-hydroxide nanoparticles with spherical morphology and its application for defluoridation of drinking water is reported. X-ray powder diffraction analysis (XRD), BET surface area, FTIR, field emission scanning electron microscopy (FESEM) and Transmission electron microscopy (TEM) images were used to characterize nanoscale iron oxide-hydroxide. Transmission electron microscopy (TEM) image revealed the formation of iron oxide-hydroxide nanoparticles with spherical morphology. The iron oxide-hydroxide nanoparticles showed an excellent ability to remove fluoride (F-) from contaminated water over a wide range of pH. The influences of temperature, stirring speed, pH, adsorbent dose and contact time were studied. The equilibrium data were tested with various isotherm models and finally, a calculation procedure was reported for the calculation of adsorbent requirement. The fluoride adsorbed nanoparticles was regenerated upto 70% using sodium hydroxide or hydrochloric acid solution. The iron oxide-hydroxide nanoparticles can be used as an effective and replicable adsorbent media for defluoridation of water in presence of competing anions like chloride, iodate, iodide and sulphate.     

坑道中水的抑爆消波性能试验研究

强爆炸冲击波对坑道内部的人员、设备和结构等均能产生巨大的毁伤破坏作用,因此如何消减冲击波强度的防护技术成为研究热点。本文以模型坑道和实际坑道为平台,系统开展了不同数量的集中置水(袋装水)和不同长度均匀置水(均布水)的消波效应试验,对试验结果进行了分析对比;并结合试验现象对水的消波机理进行了初步探讨。结果表明:无论集中置水还是均匀置水都具有显著的消波性能;直坑道内爆炸近区两者的消波效果相近,而在爆炸远区均匀置水的要高出约10%;较复杂的穿廊结构坑道比直通坑道具有更加明显的消波效果;增加置水量能提高超压衰减率,在相同位置增加相同数量水(15kg)时,即集中置水每增加1袋和均匀置水每增长1m时,超压衰减率分别提高约2%和5%;总体来说,均匀设置的消波效果更优于集中设置。     

全海深浮力材料的研究与制备

选用缩水甘油醚型环氧树脂、芳香族多胺固化剂和空心玻璃微珠等原材料制备了低密度、高强度的全海深浮力材料,研究了低密度空心玻璃微珠K1的加入量对浮力材料的密度、单轴压缩强度、耐静水压强度和吸水率等性能的影响.结果表明,在空心玻璃微珠总体积分数为66.7％的全海深浮力材料中,加入适量空心玻璃微珠K1取代空心玻璃微珠HM42,...     

Effect of Amount of Added Water During Extrusion-Spheronization Process on Pharmaceutical Properties of Granules

In order to clarify mechanism of spherical granulation using a spheronizer and its pharmaceutical properties, crystalline lactose, corn starch and theophylline were used as pharmaceutical powders, with an aqueous solution of hydroxypropylcellulose as a binder. The granules were prepared by extruding wet masses containing various amounts of water (150, 200 and 250 ml/kg). They were treated in a spheronizer for 0-10 min, and dried at 60°C for 12 min in a fluidized-bed dryer. The elongation ratio was used as an index of spheronization, and the arithmetic mean granules diameter were used as mean daimeter. The elongation ratio of the granules decreased from 5-8 to around 1.5 after 2-min spheronization. The angle of repose of spheronized granules was lower than that of the intact granules, suggesting that they had better flowability. The yield of granules obtained from addition of 250 ml/kg of water was much higher than that by adding 150 ml/kg of water, indicating that the former had a larger mean particle size than the latter. The result of mercury porosimetry showed that the amount of water in the binder solution affected the internal porosity of the spherical granules; it increased with decreasing internal porosity. The friability test suggested that the weight loss after the test was affected by the amount of water added, and it increased with decreasing amounts of water. Therefore, the quantity of water added to the granules influenced the mechanical strength of the granules. On the other hand, the hardness of tablets prepared by using a compressor at 2500 kg/cm² seemed to increase with a decrease in the mechanical strength of intact granules. And, tablets prepared from harder granules showed a capping tendency. Practical tabletting simulation using an eccentric type tabletting machine yielded the same results as those obtained by static compression.     

Effect of Amount of Added Water During Extrusion-Spheronization Process on Pharmaceutical Properties of Granules

Abstract

In order to clarify mechanism of spherical granulation using a spheronizer and its pharmaceutical properties, crystalline lactose, corn starch and theophylline were used as pharmaceutical powders, with an aqueous solution of hydroxypropylcellulose as a binder. The granules were prepared by extruding wet masses containing various amounts of water (150, 200 and 250 ml/kg). They were treated in a spheronizer for 0–10 min, and dried at 60°C for 12 min in a fluidized-bed dryer. The elongation ratio was used as an index of spheronization, and the arithmetic mean granules diameter were used as mean daimeter. The elongation ratio of the granules decreased from 5–8 to around 1.5 after 2-min spheronization. The angle of repose of spheronized granules was lower than that of the intact granules, suggesting that they had better flowability. The yield of granules obtained from addition of 250 ml/kg of water was much higher than that by adding 150 ml/kg of water, indicating that the former had a larger mean particle size than the latter. The result of mercury porosimetry showed that the amount of water in the binder solution affected the internal porosity of the spherical granules; it increased with decreasing internal porosity. The friability test suggested that the weight loss after the test was affected by the amount of water added, and it increased with decreasing amounts of water. Therefore, the quantity of water added to the granules influenced the mechanical strength of the granules. On the other hand, the hardness of tablets prepared by using a compressor at 2500 kg/cm² seemed to increase with a decrease in the mechanical strength of intact granules. And, tablets prepared from harder granules showed a capping tendency. Practical tabletting simulation using an eccentric type tabletting machine yielded the same results as those obtained by static compression.     

Defluoridation of water via doping of polyanilines

The potentiality of polyaniline and poly (m-methyl aniline) to remove fluoride from water via doping was investigated. The influence of pH, dosage of polyanilines, initial fluoride concentration and temperature on the amount of fluoride removed by the polyanilines were studied. The amount of fluoride removed at pH 7.0 by 50mg/50 ml dose was found to be 0.78 mg/g. The data of fluoride removal fitted well with Langmuir and Freundlich isotherms. Thermodynamic parameters computed show that the adsorption process is endothermic in nature. FT-IR, X-ray and EDAX patterns of the polyanilines before and after exposure to fluoride ions suggest that the defluoridation occurs via doping of fluoride ions onto these polymers.     

A summary of the Highways Agency Thaumasite Investigation in Gloucestershire: the scope of work and main findings

A summary of the scope of work, the interpretation approach and some of the main findings of the Thaumasite Investigation carried out on behalf of the Highways Agency on the trunk roads in Gloucestershire is given. The reinforced concrete structures investigated were approximately 30 years old and had been cast in situ using predominantly Grade C35-C40 concrete made using Portland cement with limestone coarse aggregates.

All of the backfill surrounding the buried concrete at each structure predominantly comprises reworked Lower Lias Clay, occasionally mixed with some alluvium. There was found to be an decrease in pyrite content and an increase in acid-soluble sulfate as the Lower Lias Clay weathered. The amount of pyrite lost in the Made Ground was generally found to be in the range 50–75%. There was no evidence of acidic ground conditions at the time of the investigations. No significant relationships were found between chemical, mineralogical or physical soil parameters and distance from concrete or degree of thaumasite attack.

Groundwater characterisation by means of Piper plots indicated that the groundwater in the Made Ground classifies as a sulfate-type and in the Lower Lias Clay as a sulfate/chloride-type. Sulfate levels in the groundwater extracted from the backfill showed a good correlation with the amount of TSA at a structure.

The extent of thaumasite attack was found to be strongly related to groundwater level. Where there was no attack, the concrete was usually above the maximum water level (i.e. permanently dry, except for percolating water) and where there was full attack, the concrete was usually below the minimum water level (i.e. permanently wet). It was found that the process of thaumasite formation leading to TSA creates four zones within structural quality concrete with a sharp reaction front. In the most severe cases of attack, the surface had a white pulpy appearance and often there was expansion. The typical pattern of attack to the buried vertical members was: no attack within 1 m of ground level; local patches of softening or blistering at mid-height; increasingly severe and more widespread attack towards the base. The maximum depth of softening was found to be approximately 45 mm and the maximum amount of expansion of the face of the concrete was 33 mm.

Bituminous coatings appeared to have provided partial protection to some structures.     

Removal of fluoride from aqueous solution using protonated chitosan beads

In the present study, chitosan in its more usable bead form has been chemically modified by simple protonation and employed as a most promising defluoridating medium. Protonated chitosan beads (PCB) showed a maximum defluoridation capacity (DC) of 1664mgF-/kg whereas raw chitosan beads (CB) possess only 52mgF-/kg. Sorption process was found to be independent of pH and altered in the presence of other co-existing anions. The sorbents were characterized using FTIR and SEM with EDAX analysis. The fluoride sorption on PCB follows both Freundlich and Langmuir isotherms. Thermodynamic parameters, viz., DeltaG degrees , DeltaH degrees DeltaS degrees and Ea indicate that the nature of fluoride sorption is spontaneous and endothermic. The sorption process follows pseudo-second-order and intraparticle diffusion kinetic models. 0.1M HCl was identified as the best eluent. The suitability of PCB has been tested with field samples collected from a nearby fluoride-endemic area.     

Evaluation of the combined deterioration by freeze–thaw and carbonation of mortar incorporating BFS,limestone powder and calcium sulfate

The durability performance of cementitious material is traditionally based on assessing the effect of a single degradation process. However, this study investigates the coupled deterioration properties of mortar incorporating industrial solid waste—ground granulated blast furnace slag (BFS) and different mineral admixtures, such as calcium sulfate (CS) and limestone powder (LSP). The combined deterioration properties caused by carbonation and frost damage in the mortar sample were experimentally investigated with respect to accelerated carbonation and freeze–thaw tests. Different degrees of deterioration, i.e. after subjected to 12, 30 and 60 freeze–thaw cycles, were induced in the freeze–thaw tests. The experimental investigation of single degradation revealed that the compressive strength, frost resistance and carbonation resistance decrease as the BFS replacement ratio increases by weight from 0 to 45%. The less amount of CH in the BFS cement leads to the carbonation progress more easily. Moreover, to achieve the same strength as ordinary Portland cement, 2 wt% CS and 4 wt% LSP in the BFS mortar are required. However, the data shows that incorporating LSP into the BFS mortar produces a lower frost resistance. The combined damage tests revealed that different deterioration degrees resulting from 12, 30 and 60 freeze–thaw cycles slightly decreased the carbonation resistance, which is related to the decrease in the inkbottle pore volume due to its water retention characteristics. Simultaneously, the pre-carbonation deterioration could effectively decrease the surface mass scaling of the freeze–thaw and the pore structure undergoes densification due to pre-carbonation.     

原位聚合法制备壳聚糖-g-聚丙烯酸/高岭土复合树脂

利用无机粘土矿物与烯类单体的接枝共聚反应制备复合高吸水性树脂,具有改善树脂吸水性能、增强凝胶强度、降低产品成本的优点。以高岭土、壳聚糖和丙烯酸为原料,在水溶液中通过接枝共聚反应合成了壳聚糖接枝共聚丙烯酸/高岭土复合吸水树脂。以丙烯酸量为基准,研究了交联剂、引发剂、壳聚糖、高岭土等与丙烯酸的不同质量比对复合树脂吸水倍率的影响。红外光谱分析结果表明,丙烯酸、壳聚糖和高岭土共同参与了接枝聚合反应。以过硫酸胺为引发剂,N,N-亚甲基双丙烯酰胺为交联剂,丙烯酸中和度为70%,引发剂用量0.3%,交联剂用量为0.05%,壳聚糖与丙烯酸的质量比为0.13,高岭土与丙烯酸质量比为0.13时,高吸水性树脂具有较好的综合吸液性能。     

Sunset yellow dyed triglycine sulfate single crystals: enhanced thermal,mechanical, optical and di-/piezo-/ferro-/pyro-electric properties

Single crystals of pure and sunset yellow (SSY) dye doped (0.05 mol%) triglycine sulphate (TGS) were grown by slow evaporation solution technique with the vision to improve the properties of pure TGS crystal. The external morphology of TGS crystal was deduced from its internal crystal structure by using two of the well established models, namely Bravais–Friedel–Donnay–Harker model (B–F–D–H) and Hartman–Perdok (H–P) periodic-bound chain (PBC) vectors model. The selective nature of sunset yellow dye to selectively stain the particular growth sectors of TGS crystal was studied. The structural analysis of both the crystals was carried out using powder XRD and FTIR studies. UV–Vis–NIR spectroscopy was carried out on both pure and SSY dyed TGS crystals to study their linear optical properties and various optical parameters namely optical band gap, refractive index, extinction coefficient and optical conductivity were determined. The thermal stability, melting point, ferro- to para-electric transition temperature, piezoelectric charge coefficient, ferroelectricity and mechanical hardness got enhanced as an effect of SSY dye doping in TGS matrix. The piezoelectric conversion efficiency (d₂₂) got enhanced from ~?56 pm/V for pure TGS single crystal to ~?85 pm/V for SSY doped TGS single crystal. The true-remanent polarization was determined for dyed TGS crystal using ‘Remanent Hysteresis Task’ which showed the presence of very small contributions of non-switchable components. ‘Time-Dependent Compensated (TDC)’ hysteresis task revealed the absence of resistive leakage in SSY-Doped TGS crystal. The pyroelectric coefficient got enhanced from ~?761 µCm^?2/°C for pure TGS single crystal to ~?850 µCm^?2/°C for SSY doped TGS single crystal. Comparative optical, mechanical, dielectric, piezoelectric, ferroelectric and pyroelectric studies provide useful scientific information of an important class of TGS crystals and suggest SSY-Doped TGS crystal as a better alternative than pure TGS crystal for various opto-electronics and ferroelectric devices applications.     

Durability of cementitious binder derived from industrial wastes

The durability of cementitious binder hydrated at 27°C and 50°C under high humidity was examined by alternate wetting and drying, as well as heating and cooling, cycles at temperatures ranging from 27°C to 60°C and by performance in water. The results show that cementitious binder hardened at 50°C possesses higher water resistance and lower porosity than the binder hardened at 27°C. A decrease in the strength of the cementitious binder was observed with an increase in temperature and in the wetting and drying and heating and cooling cycles. The maximum decrease in strength occurred at 60°C. The cementitious binder cured at 27°C showed a much smaller decrease in strength with a rise in temperature and in weathering cycles. The changes in strength of the cementitious binder were monitored by differential thermal analysis and microscopy.     

Water vapor adsorption properties of amorphous cefditoren pivoxil evaluated by adsorption isotherms and microcalorimetry

Water vapor adsorption of ground cefditoren pivoxil was studied. The amount of water adsorbed increased with a decrease in the crystallinity of cefditoren pivoxil. It was found from the microcalorimetric measurements that the differential heat of water vapor adsorption at 1.5% adsorbed water increased with decreasing crystallinity of cefditoren pivoxil, suggesting that hygroscopicity of cefditoren pivoxil was enhanced by grinding. These results indicated that hydrophilic adsorption sites in cefditoren pivoxil increased through the grinding process. The results of infrared (IR) spectra examination suggested that the increment of hydrophilic adsorption sites through the grinding process resulted from the change of the environment of the carbonyl groups in two esters and amide.     

Role of metal ion incorporation in ion exchange resin on the selectivity of fluoride

Indion FR 10 resin has sulphonic acid functional group (H(+) form) possesses appreciable defluoridation capacity (DC) and its DC has been enhanced by chemical modification into Na(+) and Al(3+) forms by loading respective metal ions in H(+) form of resin. The DCs of Na(+) and Al(3+) forms were found to be 445 and 478 mg F(-)/kg, respectively, whereas the DC of H(+) form is 265 mg F(-)/kg at 10 mg/L initial fluoride concentration. The nature and morphology of sorbents are characterized using FTIR and SEM analysis. The fluoride sorption was explained using the Freundlich, Langmuir and Redlich-Peterson isotherms and kinetic models. The calculated thermodynamic parameters such as DeltaG degrees, DeltaH degrees, DeltaS degrees and sticking probability (S(*)) explains the nature of sorption. Comparison was also made by the elution capacity of these resins in order to select a cost effective material. A field trial was carried out to test the suitability of the resins with fluoride water collected from a nearby fluoride-endemic area.     

Characterization and modification of commercial acrylic fibers grafted with acrylic acid

The graft copolymerization of acrylic acid (AA) onto commercial acrylic fibers (PAN) has been studied using Azobis(isobutyro)nitrile (AIBN) as an initiator. AA grafting initiated by radicals formed from thermal decomposition of AIBN. In this study, the effects of monomer and initiator concentration, time and temperature reaction on the grafting yield have been investigated. The optimum conditions for this grafting reaction were obtained with an AA concentration of 1.67 M, an AIBN concentration of 0.0097 M, a reaction temperature of T=85 °C and with reaction time of 60 minutes. The fiber structure has been investigated by different experimental techniques of characterization such as Fourier transform infrared spectroscopy (FT‐IR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), water absorption and also in this study has been investigated the mechanical property. The thermal analysis data showed that increasing in grafting yield, decreases the thermal stability of fiber. Grafting also affected slightly the fiber morphology. The experimental data of mechanical properties show clearly that by increasing of grafting yield, max extension will decrease. Grafting of poly AA improved water absorption.