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1.
Materials (Basel) ; 15(11)2022 May 31.
Artigo em Inglês | MEDLINE | ID: mdl-35683229

RESUMO

As the demand for nonrenewable natural resources, such as aggregate, is increasing worldwide, new production of artificial aggregate should be developed. Artificial lightweight aggregate can bring advantages to the construction field due to its lower density, thus reducing the dead load applied to the structural elements. In addition, application of artificial lightweight aggregate in lightweight concrete will produce lower thermal conductivity. However, the production of artificial lightweight aggregate is still limited. Production of artificial lightweight aggregate incorporating waste materials or pozzolanic materials is advantageous and beneficial in terms of being environmentally friendly, as well as lowering carbon dioxide emissions. Moreover, additives, such as geopolymer, have been introduced as one of the alternative construction materials that have been proven to have excellent properties. Thus, this paper will review the production of artificial lightweight aggregate through various methods, including sintering, cold bonding, and autoclaving. The significant properties of artificial lightweight aggregate, including physical and mechanical properties, such as water absorption, crushing strength, and impact value, are reviewed. The properties of concrete, including thermal properties, that utilized artificial lightweight aggregate were also briefly reviewed to highlight the advantages of artificial lightweight aggregate.

2.
Int J Biol Macromol ; 204: 593-605, 2022 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-35157900

RESUMO

Conversion of lignocellulosic biowastes from agricultural industry into nanocrystalline cellulose provides pathway to reduce environmental pollution while enhancing the economic value of biowastes. Nanocellulose (NCC) with uniform morphology was isolated from pepper (Piper nigrum L.) stalk waste (PW) using acid hydrolysis method. The role of inorganic acids (sulfuric acid, hydrochloric acid, phosphoric acid), organic acids (oxalic acid, citric acid, acetic acid) and variation of sonication times were investigated on the physicochemical characteristics, self-assembled structure, crystallinity, particle size, zeta potential and thermal stability of the isolated nanocellulose. Hydrolysis using inorganic acids transformed cellulose from PW into a spherical shaped NCC at ~33-67 nm of average diameter. Meanwhile hydrolysis in organic acids produced rod-shaped NCC at 210-321 nm in length. This study highlighted the role of acidity strength for organic acid and inorganic acid in controlling the level of hydrogen bond dissociation and the dissolution of amorphous fragments, which consequently directing the morphology and the physicochemical properties of NCCs.


Assuntos
Resíduos Industriais , Piper nigrum , Celulose/química , Hidrólise , Tamanho da Partícula
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