continuous exposure to high-energy ultrasonic waves depolymerises macromolecules in solutions and produces a permanent reduction in viscosity. different factors affect the efficiency of this ultrasonic depolymerisation. in this work ultrasonic degradation of one commercially important hydrogel based on acrylic acid and acrylamide was carried out in aqueous solution at room temperature (25oc). a...

the degradation of poly (vinyl pyrrolidone) (pvp) by means of ultrasound irradiation and itscombination with heterogenous photocatalysis (tio2 nanoparticles) was investigated. emphasiswas given on the effect of additive on degradation rate constants. 24 khz of ultrasoundirradiation was provided by a sonicator, while an ultraviolet source of 30 w was used for uvirradiation. to increase the effic...

in this study the application of zno nanoparticles to uv photocatalytic degradation of nonionic surfactanttriton x-100 in aqueous media was investigated. the affecting factors on the photodegradation such as tritonx-100 initial concentration, nanocatalyst weight, ph, temperature and other parameters were studied anddescribed in details. the degradation rate was found to be strongly influenced b...

Degradation experiments are usually used to assess the lifetime distribution of highly reliable products which are not likely to fail under the traditional life tests or accelerated life tests. Several factors, such as the inspection frequency, the sample size and the termination time, are closely related to the experimental cost and the estimation precision. Obviously, an inappropriate setting...

although extensive experimental work has been carried out during the last several years, experimental reaction rate constants are available only for hundreds of compounds. therefore, it is useful to develop a theoretical prediction method, which can be used to obtain estimates of the necessary kinetic parameters. one of the most successful approaches to predict chemical properties starting only...

field study was conducted at five villages of botswana namely, tsabong, tshane, mathathane, motlhabaneng and tsetsejwe during the periods of june to august 1999 and june to august 2000. the objective of the study was to assess and compare the soil physicochemical properties of soils at the five villages and to study the effect of cultivation on some soil physical properties. parameters measured...

high strength fresh leachates generated at a new disposal trench, compost plant and partially stabilized leachate of an older trench were characterized in terms of anaerobic degradation at laboratory batch scale at 35oc. fresh leachate had extremely high cod of 66,710 – 89,501 mg/l along with low ph of 4.1-5.9 in contrast to older and therefore partially stabilized leachate with a cod of about ...