Biomineralization of soil with crude soybean urease using different calcium salts

Calcium salt is an important contributing factor for calcium-based biomineralization.To study the effect of calcium salt on soil biomineralization using crude soybean urease,the calcium salts,including the calcium chloride (CaCl_(2)),calcium acetate ((CH_(3)COO)_(2)Ca) and calcium nitrate (Ca(NO_(3))_(2)),were used to prepare the biotreatment solution to carry out the biomineralization tests in this paper.Two series of biomineralization tests in solution and sand column,respectively,were conducted.Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were performed to determine the microscopic characteristics of the precipitated calcium carbonate (CaCO_(3)) crystals.The experimental results indicate that the biomineralization effect is the best for the CaCl2 case,followed by (CH_(3)COO)_(2)Ca,and worst for Ca(NO_(3))_(2) under the test conditions of this study (i.e.1 mol/L of calcium salt-urea).The mechanism for the effect of the calcium salt on the biomineralization of crude soybean urease mainly involves: (1) inhibition of urease activity,and (2) influence on the crystal size and morphology of CaCO_(3).Besides Ca^(2+) ,the anions in solution can inhibit the activity of crude soybean urease,and NO_(3)− has a stronger inhibitory effect on the urease activity compared with both CH_(3)COO^(−) and Cl^(−) .The co-inhibition of Ca^(2+) and NO_(3)− on the activity of urease is the key reason for the worst biomineralization of the Ca(NO_(3))_(2) case in this study.The difference in biomineralization between the CaCl_(2) and (CH_(3)COO)_(2) Ca cases is strongly correlated with the crystal morphology of the precipitated CaCO_(3).

Physiological and Biochemical Mechanisms of Exogenous Calcium Chloride on Alleviating Salt Stress in Two Tartary Buckwheat(Fagopyrum tataricum)Varieties Differing in Salinity Tolerance

Salt stress is one of the most serious abiotic stresses limiting plant growth and development.Calcium as an essential nutrient element and important signaling molecule plays an important role in ameliorating the adverse effect of salinity on plants.This study aimed to investigate the impact of exogenous calcium on improving salt tolerance in Tartary buckwheat cultivars,cv.Xinong9920(salt-tolerant)and cv.Xinong9909(salt-sensitive).Four-week-old Tartary buckwheat seedlings under 100 mM NaCl stress were treated with and without exogenous calcium chloride(CaCl_(2)),Ca^(2+)chelator ethylene glycol tetraacetic acid(EGTA)and Ca^(2+)-channel blocker lanthanum chloride(LaCl_(3))for 10 days.Then,some important physiological and biochemical indexes were determined.The results showed that salt stress significantly reduced seedling growth,decreased photosynthetic pigments,inhibited antioxidants and antioxidant enzyme activities.However,it increased the reactive oxygen species(ROS)levels in the two Tartary buckwheat cultivars.Exogenous 10 mM CaCl_(2)application on salt-stressed Tartary buckwheat seedlings obviously mitigated the negative effects of NaCl stress and partially restored seedlings growth.Ca^(2+)-treated salt-stressed seedlings diplayed a suppressed accumulation of ROS,increased the contents of total chlorophyll,soluble protein,proline and antioxidants,and elevated the activities of antioxidant enzymes compared with salt stress alone.On the contrary,the addition of 0.5 mM LaCl_(3)and 5 mM EGTA on salt-stressed Tartary buckwheat seedlings exhibited the opposite effects to those with CaCl_(2)treatment.These results indicate that exogenous Ca^(2+)can enhance salt stress tolerance and Ca^(2+)supplementation may be an effective practice to cultivate Tartary buckwheat in saline soils.

Bioavailability and Solubility of Different Calcium-Salts as a Basis for Calcium Enrichment of Beverages

Background: When usual calcium consumption patterns were analysed most people in the U.S. and Europe consume less than the recommended daily allowance. Supplements and fortified foods offer alternative and additional sources of calcium to traditional food. Calcium carbonate is the most common supplement but it is less soluble in water and, therefore, not suitable for enrichment of beverages. New organic calcium salts have a better solubility but less is known about their bioavailability. In the present study, we assessed the solubility and bioavailability of the new organic calcium salts, calcium lactate citrate and calcium lactate malate, in comparison to the traditional supplements, calcium carbonate and calcium gluconate. Design: Randomized, single-blind, four way cross-over study comparing single doses of 500 mg calcium in the form of four different calcium-salts. Subjects were advised to consume 25 μg vitamin D3 daily two weeks prior to the start of the study and during the whole study period. Subjects: 20 healthy young men, Methods: Blood samples were drawn immediately before and 2, 4, 6, 8, 12 and 24 h after ingestion of the calcium preparation. Concentration of total calcium and intact parathyroid hormone were measured in the serum. Urine was collected at baseline and during the intervals 0-3, 3-6, 9-15 and 15-24 h and excretion of calcium, sodium and creatinine was examined. Results: The tested new salts were easily water soluble, significantly better than calcium gluconate. Calcium carbonate is almost insoluble. The bioavailability of the four different calcium salts was found to be almost identical. The maximum total serum calcium increased by 7.6 % two hours after ingestion calcium lactate citrate, by 7.4 % after calcium lactate malate, by 5.5 % after calcium carbonate, and by 5.8 % after calcium gluconate. Intact parathyroid hormone concentration showed the expected depression for calcium lactate citrate, calcium lactate malate and calcium carbonate, whereas the serum level was significantly higher after ingestion of calcium gluconate. Conclusion: Given an almost equivalent bioavailability of the four tested calcium salts, we conclude that the new salts calcium lactate citrate and calcium lactate malate are well suited for fortification of beverages and thus to increase the average daily calcium intake.

Feeding Calcium Salts of Linseed Oil on Productive Performance and Milk Fatty Acid Profile in Grazing Dairy Cows

The objective of this study was to determine the effect of supplying calcium salts of linseed oil (Ca-FA) rich in omega-3 (α-linolenic acid) on the production and chemical composition of milk and its nutraceutical value in dairy cows in early lactation. The trial lasted 12 weeks (2 weeks for adaptation to lipids and 10 weeks of data collection). A total of 36 Holstein dairy cows with 58.0 ± 17.0 days in milk (DIM), 594.1 ± 92.4 kg BW, 2.6 ± 1.5 parity and 38.9 ± 9.3 kg milk day-1 were used in a randomized complete block design. The treatments were: 1) Omega-3 (O3): 5.2 kg DM day-1 of concentrate including 0.7 kg DM of Ca-FA + 13.5 kg DM day-1 of partial mixed ration (PMR) + 12 kg DM day-1 of alfalfa pasture (Medicago sativa) and 2) Control (C): diet similar to O3 but lipid supplementation was replaced by cracked corn grain so that the diets were isoenergetic. No treatment effect was detected (P > 0.05) for any milk production and composition variables, except for urea in milk that was slightly higher in O3 (P = 0.02). The treatment × week interaction was significant (P < 0.05) for fat yield and content, with differences (P < 0.01) only in the 3rd week of the data collection period in favor of group C (1.39 vs. 1.13 kg·day-1 and 3.86% vs. 3.23% for fat yield and content, respectively). Total DMI and PMR were similar (P > 0.05) between treatments. Concentrate intake was higher (P < 0.01) in C compared with O3. Pasture DMI tended (P = 0.06) to be greater for cows that received the O3 treatment compared with C. Total metabolizable energy (ME) intake was similar (P = 0.44) between treatments. No treatment effect was detected (P > 0.05) in rumen environment parameters. Supplementation with Ca-FA reduced (P < 0.05) the hypercholesterolemic fraction of milk (C12:0, C14:0 and C16:0, -13.6%, -7.4% and -9.0%, respectively). The concentration of α-linolenic acid (C18:3n-3) increased (108%, P < 0.01) in O3 group compared with group C. The absence of negative effects of lipids on the fat content of milk and ruminal fermentation suggests that protection by saponification was effective. The supplementation with Ca-FA (0.85 kg·day-1) improved the healthy value of the milk.

Efficient Separation of Butyric Acid by an Aqueous Two-phase System with Calcium Chloride

One of the bottlenecks for bioproduction of butyric acid as bulk chemical is the difficulty in separating butyric acid from the fermentation broth,compared with the petroleum-based chemical synthesis method.In the present work,a novel separation methodology was developed based on an aqueous two-phase system with inor-ganic salts.Calcium chloride was screened out for effective separation of butyric acid from butyric acid-water-salt systems.Within appropriate concentration range of butyric acid and salt,butyric acid was enriched in the upper phase and most of calcium ions remained in the lower phase.This"salting out"effect is very efficient to separate butyric acid from the simulated butyrate fermentation broth,which consists of butyric acid and acetic acid with concentration ratio of 4︰1,so that the final ratio of butyric acid/acetic acid in the upper phase is improved to 9.87. The aqueous two-phase system was used to separate butyric acid from the actual fermentation broth with satisfac-tory result.

Performance of Thermal Energy Storage Unit Using Solid Ammoniated Salt (CaCl₂-NH₃System)

The exothermic chemical reaction of CaCl2 (calcium chloride) with NH3 (ammonia) can be utilized as an energy storage system. Since this reaction is a typical gas-solid reaction, the reaction rate is controlled by the heat transfer rate. In order to improve the low heat transfer rate of the ammoniation and the deammoniation of CaCl2, the influence of a heat transfer media (Ti: titanium) on the heat transfer rate of the solid ammoniated salt (CaCl2&#46mNH3) was studied and tested experimentally. The performance tests were carried out under the conditions of various weight ratios of Ti. No decrease of the activation of chemical reaction and no corrosion of experimental apparatus were observed on the repeated runs (≥30 times each). The heat transfer rate of ammoniated salt was greatly improved by adding Ti under the constant pressure (0.5 MPa). The reaction time required for the ammoniation of CaCl2 mixed with Ti was approximately 16% - 54% shorter than that of CaCl2 alone, and the reaction time required for the deammoniation was also approximately 19% - 59% shorter than that of CaCl2 alone.

Effect of Hydrated Calcium Aluminate Cement on the Chloride Immobilization of Portland Cement Paste

To improve the efficiency and stability of chloride immobilization of portland cement paste,hydrated calcium aluminate cement(HCAC)prepared by wet grinding of CAC was added into portland cement paste as an additive.The immobilized chloride ratio(ICR)was evaluated,and the mechanism of chloride immobilization was researched by XRD,DTG,NMR,and MIP tests.The analysis results demonstrated that HCAC could improve the chloride immobilization capacity of portland cement paste.The mechanism was attributed to the following aspects:chemical binding capacity was enhanced via producing more Kuzel’s salt;physical adsorption capacity was reduced by decreasing the C-S-H gel;migration resistance was enhanced through refining the pore structure.

Influence of Calcium Sources and Concentration on the Storage Performance of Strawberry Fruit

Chemical application after harvest is an important method to preserve strawberry fruit quality and extend shelf life. The strawberry fruits harvested at red stage were treated with three different sources of calcium, i.e., calcium nitrate, calcium gluconate and calcium chloride at calcium concentration of 0% （distilled water）, 0.5%, 1.0% and 1.5%. The strawberry fruits were dipped for 30 s. The calcium sources, calcium concentration and the interaction of calcium sources and calcium concentration significantly affected the storage performance of strawberry fruits. All the three sources and concentrations were effective in decreasing the storage associated changes, i.e., weight loss, decline in marketable fruits, loss of organoleptic quality, increase in total soluble solids （TSS）, decline in reducing sugars, total sugars, acidity and increase in sugar/acid ratio in strawberry fruit, thus extending the shelf life. Calcium gluconate at 1.5% calcium concentration was more effective. Treatment of strawberry fruit with 1.5% calcium from calcium gluconate source resulted in the highest number of marketable fruit （100%）, extended shelf life （10 d）, and total soluble solid （7.80%） with the minimum weight loss （5.45%）. Calcium dips result in higher calcium concentration in strawberry fruits, which delays ripening in fruits by maintaining the structure and function of cell walls and membranes. It can be concluded that calcium gluconate at 1.5% concentration is an effective calcium treatment to retain the quality and extend the shelf life of strawberry fruit.

Chronic salt-loading downregulates large-conductance Ca^(2+)-activated potassium channel in mesenteric arterial smooth muscle cells from SD rats

Objective Large-conductance calcium-activated potassium(BKCa)channel modulates vascular smooth muscle tone.In the present study,we tested the hypothesis that salt,one of the factors which significantly influence blood pressure(BP),can regulate BKCa activity and then elevate blood pressure.Methods Male Sprague-Dawley rats aged 6 weeks were randomized into high salt diet group(HS)and control group,fed with high salt diet(containing 5% NaCl)and standard rat chow(containing 0.4% NaCl)respectively for 16 weeks.Tail systolic blood pressure(SBP),body weight(BW)and 24-hour urinary output were tested every 4 weeks.Content of urinary Na+ was detected using flame spectrophotometrical method.At the end of 16 weeks,all the rats were killed,the mesenteric arteries were obtained,and single mesenteric smooth muscle cells were isolated at once.The resting membrane potential(Em),the total potassium currents and the currents after perfusion with TEA solution of the cells were all recorded by whole cell patch clamp.The transcriptions of BKCa channel α and β1 subunits in mesenteric arterial vascular smooth muscle cells(VSMC)of each group were calculated by real-time RT-PCR.Results There was no difference in SBP and BW at each stage between control group and HS group;the urinary Na+ level in HS animals was elevated significantly after 4 weeks.The negative values of Em in HS group VSMCs were reduced compared with those in the control group.Transcriptions of β1 subunit of BKCa channels were decreased in HS group,but α subunit transcriptions did not differ between the two groups.Whole cell potassium currents did not differ between HS and control groups,but BKCa currents of HS group VSMCs were lower than those of control group ones.Conclusion Even without elevating SBP,salt-loading can still modulate the expression and activity of BKCa channel in the mesenteric arterial VSMC and elevate vascular tone.

环保型改性纳米碳酸钙降滤失剂的合成与性能评价

纳米碳酸钙在钻井液中具有降滤失及封堵作用、且环保,但分散性差、易团聚,导致效果不理想。使用硅烷偶联剂对纳米碳酸钙进行表面改性,再通过自由基共聚法将抗温、抗盐单体接枝到改性纳米碳酸钙表面,得到改性纳米碳酸钙降滤失剂SDNPJ-2,采用红外光谱(FTIR)、热重分析进行表征,同时对比评价其综合性能,通过对膨润土基浆粒径、zeta电位分析,滤饼扫描电镜(SEM)分析,考察SDNPJ-2在黏土颗粒上的吸附特征,研究改性纳米碳酸钙降滤失剂在水基钻井液中的降滤失机制。结果表明:SDNPJ-2可抗230℃高温;1%SDNPJ-2可分别使4%膨润土基浆、25%盐水基浆、10%CaCl_(2)基浆150℃/(16 h)老化后的API滤失量降低70%、89%和85%,可抗氯化钠250000 mg/L、抗氯化钙100000 mg/L,降滤失效果优于国外同类目前最优产品Driscal D;生化需氧量(BOD_(5))为558 mg/L、BOD_(5)/COD(化学需氧量)达22.6%,可生物降解;SDNPJ-2通过酰胺基团吸附于黏土表面、改善其分散性,优化体系粒径级配、通过物理堆积有效封堵滤饼和地层孔隙,两方面协同达到优良的降滤失效果。

离子微聚式物理除垢在油田供热系统中的应用

油田供热站锅炉,反冲洗水富含置换出来的钙镁离子,在高温下,造成反冲洗水管道结垢严重。通过介绍离子微聚式物理除垢技术原理,根据该技术在油田的应用分析,证实该技术在防垢除垢上的有效性,通过现场应用分析,可以看出离子微聚式防垢除垢效果明显,适用于污水排放管道系统。

钙镁二元盐复合材料的储热性能

水合盐热化学储热利用可逆的化学反应,能够在吸附与脱附过程中实现热量的释放与储存,其具有储热密度高、适合长期跨季节储热等优点,与太阳能相结合可以减少对化石能源的依赖。为探究两种不同多孔基底对钙镁二元盐复合热化学储热材料储热性能的影响,基于摩尔比为1∶2的MgCl_(2)与CaCl_(2)两种水合盐,本文对以微孔分子筛(13X)为多孔基底的MgCl_(2)/2CaCl_(2)复合材料和以介孔硅藻土(WSS)为多孔基底的MgCl_(2)/2CaCl_(2)复合材料的孔结构、平衡吸附量和循环稳定性等进行实验对比分析。采用蜂窝状储热单元的二维模型,对两种MgCl_(2)/2CaCl_(2)复合热化学储热单元的储/放热过程进行模拟对比分析。结果表明,与WSS相比,13X的孔隙更小、比表面积更大、平衡吸附量更高。由于MgCl_(2)/2CaCl_(2)的填充,两种复合材料的孔体积、比表面积、孔隙率较多孔基底均有所下降。受MgCl_(2)/2CaCl_(2)与多孔基底协同作用的影响,MgCl_(2)/2CaCl_(2)复合材料的平衡吸附量在整个相对湿度区间均有明显提升,Polanyi吸附势理论可以很好地描述MgCl_(2)/2CaCl_(2)复合材料的等温吸附线。WSS20储热单元的储热密度为371.94MJ/m^(3),可以持续输出20℃温升以上的空气198min,其放热功率和热回收效率均高于13X17储热单元。WSS20在循环47次后仍然保持完整的结构和良好的吸附量,而13X17在循环10次后发生破裂。综合储热密度和循环稳定性,WSS20更适合作为储热材料使用。

过表达胡杨PeCPK7提高拟南芥耐盐性

【目的】研究胡杨PeCPK7在植物耐盐过程中的作用,旨在进一步揭示植物耐盐的生理与分子调控机制。【方法】根据NCBI基因组数据库中胡杨PeCPK7 CDS序列,克隆PeCPK7基因,利用DNAMAN进行氨基酸序列比对,并用Mega 7软件进行进化树构建。以过表达PeCPK7拟南芥(PeCPK7-OE1、PeCPK7-OE2和PeCPK7-OE3)、野生型(WT)和转空载体对照(VC)拟南芥株系为试验材料,对各基因型拟南芥进行不同盐浓度处理,从生理生化和分子生物学水平研究胡杨PeCPK7在盐胁迫中的响应机制。【结果】(1)PeCPK7蛋白与其他物种中的CPK7有高度相似性,并与毛果杨PtrCPK7家族亲缘关系最近。(2)盐处理胡杨幼苗,PeCPK7的相对表达量在盐胁迫6 h后达到最大值,至48 h时恢复至最初状态。(3)PeCPK7定位于细胞质中。(4)在盐处理后,过表达PeCPK7拟南芥株系的生存率和根长均显著高于野生型(WT)和转空载体(VC)拟南芥;并且根细胞膜受损伤程度显著低于WT和VC。(5)在根中积累的Na^(+)和H_(2)O_(2)显著低于WT和VC,Ca^(2+)显著高于WT和VC;并且Na^(+)外排和K^(+)内流显著高于WT和VC。(6)盐胁迫下,过表达株系的超氧化物歧化酶、过氧化物酶和过氧化氢酶活性升高幅度显著高于WT和VC。(7)过表达株系的叶绿素含量、PSⅡ最大光量子效率、实际光合量子产量、相对电子传递速率和光合速率高于WT和VC,而胞间CO_(2)浓度低于WT和VC。【结论】过表达胡杨PeCPK7能够提高拟南芥的耐盐能力,本研究将为利用基因工程提高植物的耐盐性提供理论依据。

不同侵蚀环境下喷射混凝土耐久性提升技术及作用机理

为了揭示不同侵蚀环境下喷射混凝土的钙溶蚀行为,并探究羧酸酯型侵蚀抑制剂和硅灰对喷射混凝土抗侵蚀性能的影响,本文通过抗压强度及腐蚀溶液钙离子浓度测试对比了氯化铵溶蚀和复合盐侵蚀作用下喷射混凝土的强度损失率和钙离子溶出率的时变规律,并采用TG分析改性喷射混凝土侵蚀前的孔结构和可溶固相钙含量,最后采用XRD和SEM测试分析混凝土侵蚀后的物相组成和微观形貌。结果表明,复合盐侵蚀作用下较多钙矾石等腐蚀产物填充孔隙,导致混凝土强度损失和钙离子溶出率均低于氯化铵溶蚀。氯化铵溶蚀和复合盐侵蚀作用下,喷射混凝土的强度损失率与钙离子溶出率呈线性相关。4%(质量分数)侵蚀抑制剂+2%(质量分数)硅灰复合的作用效果较佳,可使喷射混凝土复合盐侵蚀28 d后的强度损失率和钙离子溶出率分别较空白组降低46.7%和50.9%。羧酸酯型侵蚀抑制剂和硅灰均可通过细化混凝土孔结构、降低氢氧化钙和钙矾石含量来提升喷射混凝土的耐久性。

钙螯合盐对牛奶-豌豆双蛋白再制干酪品质的影响

以牛奶蛋白和豌豆蛋白为原料制作牛奶-豌豆双蛋白再制干酪,基于功能特性、质构特性、感官评价和微观结构,研究不同质量分数(0.5%、1.0%、1.5%和2.0%)的3种钙螯合盐(柠檬酸三钠(TSC)、磷酸氢二钠(DSP)和六偏磷酸钠(SHMP))对该双蛋白再制干酪品质的影响。结果表明:牛奶蛋白和豌豆蛋白可替代天然干酪在再制干酪中的作用,且随着钙螯合盐质量分数的增加,各双蛋白再制干酪的融化性均呈上升趋势,油脂析出性均呈下降趋势,其中TSC在提升产品融化性及抑制油脂析出方面效果较好;当TSC的质量分数为1.0%时,双蛋白再制干酪的硬度较低,感官评分总分、弹性、粘力和粘附能量均较高,酪蛋白网状胶束呈规则排列,其包裹的脂肪球和矿物质均匀分布在矩阵系列中。因此,添加TSC有助于改善牛奶-豌豆双蛋白再制干酪的品质,增强产品的乳化性、稳定性等功能特性。

10-MDP钙盐对小鼠成纤维细胞L929增殖、凋亡及MMPs表达的影响

目的通过10-MDP钙盐对小鼠成纤维细胞L929的研究调查了不同浓度不同结构的10-MDP钙盐对牙周组织的影响。方法通过X射线衍射(X-Ray diffraction,XRD)对合成的三种不同比例10-MDP钙盐进行鉴定。使用CCK-8法检测10-MDP钙盐对小鼠成纤维细胞L929的细胞增殖毒性;流式细胞术检测细胞凋亡;蛋白免疫印迹实验检测细胞基质金属蛋白酶(matrix metalloproteinase,MMP)2、MMP9表达。结果XRD的结果证实三种合成方式均有不同结构10-MDP钙盐的产生;细胞增殖毒性CCK-8实验中仅有1.0 mg/mL MDP-1组在72 h后引起细胞增殖活性降低;各组培养72 h后均不诱导细胞凋亡;0.2 mg/mL和0.1 mg/mL MDP-2、MDP-1组均抑制L929细胞的MMP2和MMP9蛋白分泌。结论10-MDP钙盐可能对牙周组织中成纤维细胞没有细胞毒性作用,并且可以通过抑制MMP2、MMP9蛋白的分泌减少牙周组织破坏。

钻井滤液中硫酸根去除方法研究

钻井滤液中硫酸根(SO_(4)^(2-))浓度高、复配钻井液性能差是海上钻井滤液循环利用面临的主要难题之一。文章以钻井滤液为研究对象,分别探究了钙盐沉淀法和钙矾石沉淀法对SO_(4)^(2-)去除的影响,提出了钙盐-钙矾石沉淀法去除SO_(4)^(2-)的技术。结果表明:钙盐沉淀法或钙矾石沉淀法处理后,钻井滤液中的SO_(4)^(2-)和Ca^(2+)浓度无法满足钻井滤液回用要求(SO_(4)^(2-)≤4000 mg/L;Ca^(2+)≤500 mg/L);钙盐-钙矾石沉淀法处理后钻井滤液中SO_(4)^(2-)和Ca^(2+)浓度可分别降至2218 mg/L和465 mg/L,满足钻井滤液回用要求。反应条件为:钙盐沉淀法中投加12000 mg/L的CaCl_(2)溶液,钙矾石沉淀法中,Al/S摩尔比(IAS)和Ca/S摩尔比(ICS)分别为1.25和2.5。研究结果可为钻井滤液中SO_(4)^(2-)处理工艺单元的设计和运行提供参考。

硫酸根对废旧电池废水中氟离子去除的影响研究

含氟废水广泛存在,其中钙盐沉淀是处理高氟废水常用方法之一。但是在处理实际废水时,往往达不到理想效果,需要混凝二级处理。为此,本研究以某实际电池高氟废水为例,研究钙盐沉淀运行参数对除氟效果影响,发现在钙盐投加量4500~5000 mg·L^(-1)、pH为11.5条件下,除氟效果最佳,但无法达到理论要求的8 mg·L^(-1)。随后通过配水实验探究了废水中的共存离子对钙盐除氟的干扰,发现在硫酸根存在的条件下,无法降到10 mg·L^(-1)以下。通过能量色散X射线光谱仪(EDS)傅里叶红外光谱(FTIR)和X射线衍射仪(XRD)分析表明,硫酸根通过与氟离子竞争钙离子,从而抑制了氟离子的去除。最后,废水再经过铝盐混凝处理或者投加磷酸盐生成氟磷酸钙沉淀后,满足污水排放要求。

焚烧飞灰深度资源化技术进展及展望

基于生活垃圾焚烧飞灰的产生方式及特性,探析了焚烧飞灰中无机氯盐回收处理技术、钙元素分离回收技术、重金属分离提取技术,分析各项技术存在的优缺点,并总结了目前焚烧飞灰的最新资源化利用工业化进展。研究得出,被广泛认可的两套系统包括:低温二噁英解毒-水洗-含重金属盐水蒸发回收-钙组分用于水泥材料、高温烧结/熔融二噁英解毒-盐及重金属挥发回收-钙组分形成陶粒或玻璃体。这些系统中二噁英均能得到有效处理;钙组分可资源化但是附加值不高,且钙资源化过程中需要关注重金属进入环境的总量所带来的长期环境风险;氯盐组分目前缺乏有成本效益的资源化途径。综上,未来需要在研发飞灰中钙及氯盐的有效资源化技术、出台更多细分技术的指导性文件作为理论支撑和设计依据方面进行深入研究。

糖液与钙盐组合渗透脱水处理对冻融蓝莓品质的影响

为探究钙盐作为冷冻保护剂与高浓度糖液浸渍组合在常温下进行渗透脱水处理对冷冻蓝莓融化后质地品质的影响。对比以丙酸钙、乳酸钙、氯化钙为代表的3种钙盐冷冻保护剂及质量浓度为0.5、1.5、3.0、5.0 g/mL丙酸钙处理对冻融蓝莓品质的影响。通过观测蓝莓冻融后外观,测定硬度值、弹性、咀嚼性、胶着性、内聚性和回复性品质指标及可溶性果胶、共价结合型果胶和离子结合型果胶的含量。结果表明:添加钙盐结合糖液渗透脱水处理组均可减少蓝莓冻融后皱缩和质地瘫软现象,丙酸钙结合糖液渗透脱水处理组的汁液流失率比对照组降低约25.42%,显著低于(P<0.05)其他处理组,丙酸钙处理组为较优的钙盐添加种类。对丙酸钙添加浓度进行优化筛选,发现当丙酸钙添加浓度为1.5g/mL时可显著降低(P <0.05)蓝莓果实的汁液流失和细胞膜透性,冻融后硬度为1.54 N、弹性0.75 mm,可溶性果胶、共价结合型果胶和离子结合型果胶含量分别达到1.03、0.83和0.68 mg/g,减少蓝莓果实的质地瘫软现象并保持最佳冻融品质。丙酸钙浓度为1.5 g/mL结合渗透脱水技术使冻融蓝莓具有更好的品质,有利于食用和加工。研究结果不仅为解决蓝莓加工行业出现的由于长期冷冻所造成果实质地瘫软问题提供数据基础,还为研发提升果蔬原料冷冻贮藏品质的助冻剂及改性技术提供一定的理论依据。