Flotation (flotasi) berasal dari kata float yang
berarti mengapung atau mengambang. Flotasi dapat diartikan sebagai suatu
pemisahan suatu zat dari zat lainnya pada suatu cairan/larutan berdasarkan perbedaan
sifat permukaan dari zat yang akan dipisahkan, dimana zat yang bersifat
hidrofilik tetap berada fasa air sedangkan zat yang bersifat hidrofobik akan
terikat pada gelembung udara dan akan terbawa ke permukaan larutan dan
membentuk buih yang kemudian dapat dipisahkan dari cairan tersebut. Secara umum
flotation melibatkan 3 fase yaitu cair (sebagai media), padat (partikel yang
terkandung dalam cairan) dan gas (gelembung udara).
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Tuesday, January 29, 2019
Saturday, January 26, 2019
ZAT-ZAT YANG DAPAT TERBAKAR DAN MELEDAK
Dalam pengertian luas zat yang dapat terbakar adalah sesuatu
yang siap terbakar, sedangkan zat yang dapat meledak relative memerlukan
rangsangan untuk terbakar. Sebelum mencoba mecermati definisi-definisi ini perlulah
kiranya menetapkan beberapa terminology lain. Kebanyakan zat kimia yang
cenderung terbakar tak sengaja adalah berupa cairan. Cairan menimbulkan uap,
yang biasanya lebih pekat dari pada udara, dan karenanya bertendensi untuk
terbakar. Tendensi dari pada suatu cairan untuk terbakar dapat diukur dengan
sebuah pengujian dengan cairan dipanaskan dan secara priodik diekspose terhadap
nyala api hingga campuran uap dan udara menyala pada permukaan cairan. Temperatur
yang terjadi ini dinamakan titik nyala/flash point.
Tuesday, January 22, 2019
A NEW NATURE-HUMAN RELATIONSHIP
A
critical environmental education consists of developing, not only among youth,
but the population in general, the capacities to analyze educational
propositions regarding the environment and dominant environmental discourses to
decode hidden ideological orientations, the beliefs and interests that direct them,
and which implicitly tend to reproduce the practices that are nevertheless the
ones that would be necessary to shift to a different kind of relationship between
nature and human beings. The reference to science and technological transfers
as the main answer to defining and correcting the problem is insufficient to
correct a situation that requires that humans also question the philosophic
foundations, sociological, political, and economic dimensions of the regulation
of climate. To reproduce the same economic logic is denounced by many as
incapable of
correcting the shameless exploitation of nature and human beings that are at
the heart of the environmental crisis.
Saturday, January 19, 2019
ENVIRONMENTAL EDUCATION AND SUSTAINABILITY
The fourth report of the Intergovernmental Panel on
Climate Change (IPCC), published in February 2007, confirms the reality of
global climate change. Some scientists have pointed to the uncertainties and
the inevitable limits of the climatic modeling, and other researchers question
the ascendancy of scientist’s analyses of the question in the public sphere.
They assert that sociopolitical analyses should lead scholars to question the
neo-liberal model of society, with its faith in technical progress, as well as
the inequitable sharing of the wealth which ensues from it, according to Scott
Lash, et al. The consensus of the IPCC experts has strengthened over the years,
and concludes that the production of greenhouse gas of human origin is an important
cause of global warming.
Tuesday, January 15, 2019
WHAT ARE SOME STRATEGIES TO REDUCE THE AMOUNT AND/OR TOXICITY OF CHEMICAL WASTE GENERATED IN THE LABORATORY?
All laboratories that use chemicals inevitably produce
chemical waste that must be properly disposed of. It is crucial to minimize
both the toxicity and the amount of chemical waste that is generated. A waste
management and reduction policy that conforms to State and local regulations
should be established by the school or school district. Several things that can
be done to minimize hazards, waste generation, and control costs follow:
Wednesday, January 9, 2019
ENVIRONMENTAL CHEMMISTRY
Environmental chemistry is the study of the sources,
reactions, transport, effects, and fates of chemical species in the water, air,
terrestrial, and living environments and the effects of human activities
thereon. Some idea of the complexity of environmental chemistry as a discipline
may be realized by examining, which indicates the interchange of
chemical species among various environmental spheres. Throughout an
environmental system there are variations in temperature, mixing, intensity of
solar radiation, input of materials, and various other factors that strongly
influence chemical conditions and behavior. Because of its complexity,
environmental chemistry must be approached with simplified models. This chapter
presents an overview of environmental chemistry
TOXICOLOGICAL
CHEMISTRYAND
BIOCHEMISTRY
THIRD EDITION
CHEMISTRYAND
BIOCHEMISTRY
THIRD EDITION
In order to understand toxicological chemistry, it is
necessary to have some understanding of the environmental context in which
toxicological chemical phenomena occur. This in turn requiresan understanding
of the broader picture of environmental science and environmental
chemistry,which are addressed in this chapter. Also needed is an understanding
of how environmentalchemicals interact with organisms and their ecosystems, as
addressed by the topic of ecotoxicology.
Environmental science can be defined as the study of the
earth, air, water, and living environments, and the effects of technology
thereon.1 To a significant degree, environmental science hasevolved from
investigations of the ways by which, and places in which, living organisms
carry outtheir life cycles. This is the discipline of natural history, which in
recent times has evolved intoecology, the study of environmental factors that
affect organisms and how organisms interact withthese factors and with each
other.
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