The adsorption characteristics of this modified biomass ash for [Cd.sup.2+] in aqueous solution had been researched using batch experiments.
Adsorption isotherms were obtained with several initial adsorbate concentrations from 50 to 100 mg/L in 25 mL of solution at pH 5.0 with 0.1 g of adsorbent.
Adsorption Experiments: The adsorption ability of adsorbent was studied under different conditions of pH, agitation speed, temperature etc.
The effect of acid treatment on adsorption efficiency was determined at optimum conditions following the procedure reported by (Stephen and Sulochana2002).
The latter, is one of the most important methods of waste water treatment; it is based on the use of the activated carbon as adsorbent because of its excellent properties of adsorption, but the high cost of activated carbon has prompted several researchers to find other low-cost adsorbents for the elimination of coloring agents from contaminated water, for example some few inexpensive biosorbents are used to eliminate the cationic dye, the methylene blue, including yellow passion fruit waste , bagasse , neem (azadirachta indica) leaf powder , posidonia oceanica , coffee husks , papaya seeds  and brazilian pine-fruit shell .
In addition, they have active sites on their surface such as hydroxyl, carboxyl, amino, sulfhydryl and sulfonate, which are important in adsorption mechanisms [18, 19].
Ezahri, "Acridine orange adsorption by zinc oxide/almond shell activated carbon composite: operational factors, mechanism and performance optimization using central composite design and surface modeling," Journal of Environmental Management, vol.
Thomas, "Rapid methylene blue adsorption using modified lignocellulosic materials," Process Safety and Environmental Protection, vol.
The specific surface was measured by the BET technique using isothermal [N.sub.2] adsorption
. The procedure for the deprotonation reaction of the calcined substrate (substrate activation) is also described in the same literature were the substrate is chemically treated with a NaOH 0.1 M solution during 12 h and finally the excess of alkali is wash out with distillate water until it reaches pH 7, and later it dries in a furnace at 120[degrees]C.
The decreased uptake of the metal ions was probably due to reduced available active sites for adsorption
as a result of saturation of the active surface sites of PMSAC with metal ions .
The scale inhibition of circulating water and adsorption
properties of adsorbents for [Pb.sup.2+] and phenol were studied.
Therefore, a series of experiments were conducted to understand how are the impacts of pH, amount of organic matter, and temperature on Cu(II) adsorption
and desorption in single-metal solutions.