Biochar is a stabilized, carbon-rich by-product derived from pyrolysis of biomass. Recently, biochar has received extensive attentions because of its multi-functionality for agricultural and environmental applications. Biochar can contribute to sequestration of atmosphere carbon, improvement of soils quality, and mitigation of environmental contaminations. The capability of biochar for specific application is determined by its properties which are predominantly controlled by source material and pyrolysis route variables. The biochar sorption potential is a function of its surface area, pores volume, ash contents, and functional groups. The impacts of each production factors on these characteristics of biochar need to be well-understood to design efficient biochars for pesticides removal. The effects of biomass type on biochar sorptive properties are determined by relative amounts of its lingo-cellulosic compounds, minerals content, particles size, and structure. The highest treatment temperature is the most effective pyrolysis factor in the determination of biochar sorption behavior. The expansion of micro-porosity and surface area and also increase of biochar organic carbon content and hydrophobicity mostly happen by pyrolysis peak temperature rise. These changes make biochar suitable for immobilization of organic contaminants. Heating rate, gas pressure, and reaction retention time after the pyrolysis temperatures are sequentially important pyrolysis variables effective on biochar sorptive properties. This review compiles the available knowledge about the impacts of production variables on biochars sorptive properties and discusses the aging process as the main factor in post-pyrolysis alterations of biochars sorption capacity. The drawbacks of biochar application in the environment are summarized as well in the last section.

Changes in crude oil production and distribution have increased the incidence of oil spills throughout the world. Oil spills often cause destructive effects on aquatic and land ecosystems. The oil spill cleanup and recovery techniques are challenging and usually involve complex mechanical, chemical, and biological methods. Usually, mechanical removal of free oil is utilized as an effective strategy for cleanup in aquatic and terrestrial environments; however, they are expensive and need specialist personnel and equipment. The other commonly used method is the application of chemical materials such as dispersants, cleaners, demulsifiers, biosurfactants, and soil oxidizers. Nevertheless, these reagents can have potential harmful environmental impacts, which may limit their application. As an alternative, bioremediation can offer reduced environment risk; however, the limitations of microbial activity in the soil can make this option unsuitable. One area of bioremediation is phytoremediation, which offers potential for restoring large areas of contaminated ground. Plants are able to remove pollutants through processes such as biodegradation, phytovolatilization, accumulation, and metabolic transformation. This review presents the fate of crude oil spills in aquatic and land ecosystems and their environmental effects. Furthermore, the paper focuses on crude oil phytoremediation and its applications in polluted ecosystems.

No abstract

The removal of Pb (II) and Cu (II) ions by using marine red macroalgae (Gracilaria changii) as a biosorbent material was evaluated through the batch equilibrium technique. The effect of solution pH on the removal of metal ions was investigated within the range of 2–7. The response surface methodology (RSM) technique involving central composite design (CCD) was utilised to optimise the three main sorption parameters, namely initial metal ion concentration, contact time, and biosorbent dosage, to achieve maximum ion removal. The models’ adequacy of response was verified by ANOVA. The optimum conditions for removal of Pb (II) and Cu (II) were as follows: pH values of 4.5 and 5, initial concentrations of 40 mg/L, contact times of 115 and 45 min, and biosorbent dosage of 1 g/L, at which the maximum removal percentages were 96.3% and 44.77%, respectively. The results of the adsorption isotherm study showed that the data fitted well with the Langmuir’s model for Pb (II) and Cu (II). The results of the adsorption kinetic study showed that the data fitted well with the pseudo-second order model for Pb (II) and Cu (II). In conclusion, red alga biomass exhibits great potential as an efficient low-cost sorbent for removal of metal ions.

Characteristics and efficiency of wasted black tea (WBT) were investigated as a low-cost sorbent in removal of Ni 2+ and Zn 2+ ions from aqueous solution. Initial findings showed WBT potential to be applied as an effective sorbent due to high concentrations of carbon and calcium and high porosity and availability of functional groups. Sorption dynamics were studied with varying pH, contact time, and adsorbent dose. Maximum percentages of metal ions removal were recorded at pH 5, contact time 250 min, and 20 g/L of adsorbent concentration. Binary metal sorption studies showed that Ni 2+ and Zn 2+ do not compete with each other for available sorption sites, so the adsorption trend in binary system appears similar to monocomponent metal adsorption. Evaluation of the isotherms confirmed that WBT has high value of adsorption capacity. Sorption data fitted well with both Freundlich and Langmuir models. In the optimum conditions, maximum capacity of WBT could reach up to 90.91 mg-Ni/g adsorbent and 166.67 mg-Zn/g adsorbent. This experiment demonstrated the ability of tea waste as an effective, sustainable, and low-cost adsorbent for removal of the heavy metal ions.

Biochar is the bio-solid material produced by pyrolysis. The biochar properties are controlled by feedstock and pyrolysis variables. In this study, the impacts of these production variables on biochar yield and physicochemical properties including pH, cation exchange capacity (CEC), total organic carbon (TOC) content, surface area, and pore volume and size were investigated. Rice husk (RH) and oil palm empty fruit bunches (EFB) were used as biomass. The biochars were produced at temperature range of 300 to 700 °C, heating rate of 3 to 10 °C/min and retention time of 1 to 3 h. The pyrolysis conditions were optimized using response surface methodology (RSM) technique to maximize the values of the responses. Analysis of variance (ANOVA) of the results demonstrated that the data fitted well to the linear and quadratic equations. Temperature was found to be the most effective parameter on the responses followed by retention time and heating rate, sequentially. CEC, TOC, surface area, and pore characteristics were evaluated as biochar properties determining their sorption potential. The optimum conditions for the maximum values of the properties were temperatures of 700 and 493.44 °C and time of 3 and 1 h for RH and EFB biochars, respectively. Heating rate at 3 °C/min was found to be the best rate for both biochars. The structure of EFB biomass was more sensitive to heating than rice husk. The biomass type and the production variables were demonstrated as the direct effective factors on biochar yield and physicochemical properties.

No abstract

Purpose Huge amount of yard waste is produced in cities with excessive agricultural activities like Cameron Highlands, Malaysia where most of the time the yard waste is being managed poorly and big portion of it ends in dump sites. Therefore, this study aims to evaluate the applicability of converting yard waste generated in Cameron Highlands Malaysia into high-quality and fast compost via in-vessel method. Methods In-vessel composting technique was applied for speedy biotransformation of yard waste. Addition of food waste, effective microorganisms (EM) and Shimamoto Enzyme Ò (SE) were investigated for improvement of compost quality. Four compositions of feedstock with different yard waste (YW) and food waste (FW) ratios were tested. The compositions were 70%YW ? 30%FW, 80%YW ? 20%FW, 90%YW ? 10%FW and 100%YW. Physicochemical properties of compost including pH, moisture content and C/N ratio were monitored throughout the experiment. Furthermore, quality of compost and its potential for direct application after production were evaluated based on germination index (GI) and nutrient content (NPK). Results The compost samples had pH ranging from 7 to 9 and moisture content of 15.45-32.13%. Initial C/N ratio of all feedstock was decreased throughout the composting process by more than 50%. Seed germination test showed that only 70%YW ? 30%FW feedstock produced immature compost with GI \ 80%. The highest GI of 130% was obtained when FW represented in 10% of the feedstock with addition of EM. Average concentrations of nitrogen, phosphorus and potassium were 1.73, 1.21 and 1.66% in case of EM additive and 1.47, 0.56 and 1.74% in case of SE additive. Conclusion Application of in-vessel composting can improve solid waste management in Cameron Highlands, Malaysia and yield a high-demand product. The approach used in this study can be a good practice for the societies have difficulties in managing their yard waste.