A hidrólise alcalina como acelerador da degradação da casca do coco seco

• Autor(a) principal: Amorim Neto, Manoel Ferreira de
• Data de Publicação: 2020
• Tipo de documento: Trabalho de conclusão de curso
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Federal de Alagoas (UFAL)
• Texto Completo: http://www.repositorio.ufal.br/handle/riufal/7140
• topic: cal hidratada; resíduo agroindustrial; hidróxido de sódio; fibra de coco; hydrated lime; agro-industrial waste; coconut fibers; sodium hydroxide; CNPQ::CIENCIAS AGRARIAS

Coconut cultivation is one of the main socioeconomic activities in the Northeast region, generating direct and indirect jobs. For non-agricultural purposes, only part of the skins generated by this large amount of fruit is used and the surplus results in major environmental problems, caused by significant volumes of waste. In this sense, the recycling of organic waste through composting is an important alternative for the use of coconut husks on the farm. However, one of the challenges for using dry coconut shells to obtain organic compounds is its slow degradation, resulting from its high C / N ratio and high lignin content, requiring longer processing time. A potential strategy for the degradation of coconut fibers is the use of alkaline agents, such as quicklime, hydrated lime or NaOH (chemical hydrolysis). Such research aims to evaluate the effect of alkaline hydrolysis on the behavior of biochemical parameters during the incubation of dry coconut shell with hydrated lime and sodium hydroxide. The experiment was conducted at Embrapa Tabuleiros Costeiros Research and Execution Unit (UEP), in Rio Largo, AL. For this purpose, samples of 300 g (dried at 50 oC) of crushed dry coconut shell received 300 ml of aqueous solutions with increasing doses of Ca (OH) 2 PA (0; 0.135; 0.270; 0.405 or 0.540 mol L-1 ) or NaOH PA (0; 0.25; 0.5; 0.75 or 1.0 mol L-1) equivalent to the proportion of 0, 1, 2, 3 and 4% of the dry mass of dry coconut shell. The assay was developed in a completely randomized design, in a 2 x 5 factorial scheme, with three replications, being sampled at 0, 7, 15, 30 and 60 days after the beginning of the assay. The samples were weighed, dried at 50 oC, ground and subjected to the determination of electrical conductivity (EC) and pH in water; dry matter at 65 and 105oC, ash, neutral detergent fiber (NDF), acid detergent fiber (FDA) and hemicellulose. For the comparison of the chemical agents, the data, obtained in each evaluated character, were submitted to the analysis of variance and the averages, compared through the Tukey test, to 5% of probability. The evaluation of the effect of the doses of Ca (OH) 2 and NaOH and incubation time on the degradation of the coconut shell, was done through regression analysis. Significant effects were observed for both the alkaline agents and the doses tested. At the end of the period, the use of NaOH resulted in higher values of pH, EC and ash in the CCS and the hydrated lime was more effective in reducing the NDF, ADF and cellulose contents. The pre-treatment of the dry coconut shell for composting purposes by means of alkaline hydrolysis with Ca (OH) 2, proved to be more adequate in accelerating the degradation of this residue than NaOH. Its use allowed a significant attack on the fibers of the dry coconut shell,without altering the characteristics of those who may harm its use for composting purposes.