Biocoagulants emerges as a promising technology in water treatment,in order to exploit renewable and biodegradable materials.The present work aims to study the coagulant action of chitosan and carboxymethylchitosan on...Biocoagulants emerges as a promising technology in water treatment,in order to exploit renewable and biodegradable materials.The present work aims to study the coagulant action of chitosan and carboxymethylchitosan on water with very high turbidity(above 300 NTU),contrasting the physicochemical results with those obtained for aluminum sulphate.Carboxymethylchitosan was produced by the Williamson’s ethers synthesis and characterized by potentiometric titration,FTIR and 1 H-NMR.The coagulant tests were performed using synthetic water in a Jar-test equipment,through the induction of high and low velocity gradients,followed by sedimentation.The results showed turbidity and color removal efficiencies above 99%for the biocoagulants,by applying dosages much lower than those used for aluminum sulphate;the volume of sedimentable solids obtained at the end of the water treatment process was much lower when chitosan and carboxymethylchitosan were used as coagulants(reduction of 25%when compared to aluminum sulphate).In summary,carboxymethylchitosan is a non-toxic,renewable,biodegradable material with high efficiency as a coagulant for waters with very high turbidity,showing promise for in natura applications.展开更多
The purpose of this paper is to present the rationale for registration of the Seated Condylar Position (SCP)/Centric Relation (CR) position of the condyles.
The purpose of this paper is to present the technique for registration of the Seated Condylar Position (SCP)/Centric Relation (CR) position of the condyles: a two-piece wax bite registration with deprogramming and no ...The purpose of this paper is to present the technique for registration of the Seated Condylar Position (SCP)/Centric Relation (CR) position of the condyles: a two-piece wax bite registration with deprogramming and no mandibular manipulation.展开更多
基金The authors would like to thank CNPq for financial support[Project Number 442965/2014-1].
文摘Biocoagulants emerges as a promising technology in water treatment,in order to exploit renewable and biodegradable materials.The present work aims to study the coagulant action of chitosan and carboxymethylchitosan on water with very high turbidity(above 300 NTU),contrasting the physicochemical results with those obtained for aluminum sulphate.Carboxymethylchitosan was produced by the Williamson’s ethers synthesis and characterized by potentiometric titration,FTIR and 1 H-NMR.The coagulant tests were performed using synthetic water in a Jar-test equipment,through the induction of high and low velocity gradients,followed by sedimentation.The results showed turbidity and color removal efficiencies above 99%for the biocoagulants,by applying dosages much lower than those used for aluminum sulphate;the volume of sedimentable solids obtained at the end of the water treatment process was much lower when chitosan and carboxymethylchitosan were used as coagulants(reduction of 25%when compared to aluminum sulphate).In summary,carboxymethylchitosan is a non-toxic,renewable,biodegradable material with high efficiency as a coagulant for waters with very high turbidity,showing promise for in natura applications.
文摘The purpose of this paper is to present the rationale for registration of the Seated Condylar Position (SCP)/Centric Relation (CR) position of the condyles.
文摘The purpose of this paper is to present the technique for registration of the Seated Condylar Position (SCP)/Centric Relation (CR) position of the condyles: a two-piece wax bite registration with deprogramming and no mandibular manipulation.
文摘以甲壳素为原料,95%乙醇为反应介质,一锅连续法制备羧甲基壳聚糖的适宜条件为:m(甲壳素)∶m(氢氧化钠)∶m(一氯乙酸)=1∶2.5~3.5∶3~4,脱乙酰化反应温度90℃~100℃;羧甲基化反应温度40℃~50℃,反应时间3 h^4 h,羧甲基壳聚糖产率可达115%(以甲壳素计),羧化度为1.16,4%水溶液的黏度为1662 m Pa.s。该法用碱量小,反应时间短,用水少,无废液排放,顺应环保要求而且产品黏度高。收率大,可降低其生产成本。
